49 results on '"Kyung-Hwan Jung"'
Search Results
2. A facile and efficient method for the synthesis of crystalline tetrahydro-β-carbolines via the Pictet-Spengler reaction in water
- Author
-
Gi-Seong Moon, Kyung-Hwan Jung, Sung-Kwon Moon, Hyang-Yeol Lee, and Hong-Ju Byeon
- Subjects
Tryptamine ,Multidisciplinary ,Pictet–Spengler reaction ,Cancer therapy ,010405 organic chemistry ,Natural compound ,Biological techniques ,lcsh:R ,lcsh:Medicine ,One-Step ,010402 general chemistry ,01 natural sciences ,Environmentally friendly ,Article ,0104 chemical sciences ,Solvent ,chemistry.chemical_compound ,chemistry ,Organic chemistry ,Drug discovery and development ,lcsh:Q ,Tryptoline ,Cytotoxicity ,lcsh:Science - Abstract
A facile and efficient synthesis of tetrahydro-β-carbolines (tryptolines) in one step from tryptamine and aldehydes, in an environmentally friendly water solvent, has been investigated. This convenient and clean synthesis of various tryptolines was facilitated by l-tartaric acid, a natural compound, to obtain the desired products as clear crystals. Among the four crystalline products, the most substituted tryptoline 2 showed the best inhibitory activity against EJ cells and the least cytotoxicity, with an LC50 value of 1.49 mg/mL, against brine shrimp larvae.
- Published
- 2020
3. Continuous Synthesis of Chlorphenesin Galactoside
- Author
-
Kyung-Hwan Jung
- Subjects
chemistry.chemical_compound ,chemistry ,Biochemistry ,medicine ,medicine.disease_cause ,Galactoside ,Escherichia coli - Published
- 2019
4. Effects of sodium dodecyl sulfate surfactant on up-conversion luminescence of Er3+/Yb3+ -codoped NaLa (MoO4)2 nanocolloidal phosphor prepared by pulsed laser ablation in water
- Author
-
Kang Min Kim, Sungwook Mhin, Jeong Ho Ryu, HyukSu Han, Won Rae Kim, Kyung-Hwan Jung Suk Hyun Kang, Yong Son, Jung-Il Lee, and Kwang Bo Shim
- Subjects
chemistry.chemical_compound ,Materials science ,chemistry ,Pulmonary surfactant ,Ceramics and Composites ,Up conversion ,Phosphor ,Sodium dodecyl sulfate ,Luminescence ,Pulsed laser ablation ,Nuclear chemistry - Published
- 2019
5. Publisher Correction: Graphene Oxide Quantum Dots Derived from Coal for Bioimaging: Facile and Green Approach
- Author
-
Sungwook Mhin, Byoung-Soo Lee, Yong Son, Kang Min Kim, Jeong Ho Ryu, Kwang Bo Shim, Kyung-Hwan Jung, Suk Hyun Kang, Taeseup Song, and HyukSu Han
- Subjects
Multidisciplinary ,Materials science ,Graphene ,business.industry ,lcsh:R ,Oxide ,lcsh:Medicine ,Nanotechnology ,law.invention ,chemistry.chemical_compound ,chemistry ,law ,Quantum dot ,lcsh:Q ,Coal ,lcsh:Science ,business - Abstract
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
- Published
- 2020
6. Laser wavelength modulated pulsed laser ablation for selective and efficient production of graphene quantum dots
- Author
-
HyukSu Han, Jeong Ho Ryu, Kyung Hwan Jung, Kwang Bo Shim, Kang Min Kim, Suk Hyun Kang, and Byoung-Soo Lee
- Subjects
Photoluminescence ,Materials science ,business.industry ,Graphene ,General Chemical Engineering ,Oxide ,Coulomb explosion ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Laser ,01 natural sciences ,0104 chemical sciences ,Nanomaterials ,law.invention ,chemistry.chemical_compound ,Wavelength ,chemistry ,Quantum dot ,law ,Optoelectronics ,0210 nano-technology ,business - Abstract
Graphene quantum dots (GQDs) and graphene oxide quantum dots (GOQDs) can be used in different applications such as optoelectronic and biomedical applications, respectively. Hence, the selective synthesis of GQDs and GOQDs is highly desirable but challenging. Here, we present GQDs and GOQDs selectively prepared by an easy and simple pulsed laser ablation in liquid (PLAL) method by controlling the laser wavelength. The obtained GQDs and GOQDs showed a significantly different optoelectronic nature mainly due to the existence of surface oxygen-rich functional groups (e.g. carboxyl or hydroxy groups). Also, we described a possible mechanism for the formation of oxygen functional groups during the PLAL process based on the Coulomb explosion model, which can give further insight for designing functional carbon materials.
- Published
- 2019
7. Graphene Oxide Quantum Dots Derived from Coal for Bioimaging: Facile and Green Approach
- Author
-
Yong Son, Sungwook Mhin, Kang Min Kim, Taeseup Song, Jeong Ho Ryu, HyukSu Han, Kyung-Hwan Jung, Kwang Bo Shim, Byoung-Soo Lee, and Suk Hyun Kang
- Subjects
0301 basic medicine ,Materials science ,Oxide ,lcsh:Medicine ,chemistry.chemical_element ,Nanotechnology ,Carbon nanotube ,Article ,law.invention ,Pulsed laser ablation ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,law ,Coal ,lcsh:Science ,Multidisciplinary ,business.industry ,Graphene ,lcsh:R ,Publisher Correction ,030104 developmental biology ,chemistry ,Quantum dot ,lcsh:Q ,business ,Carbon ,030217 neurology & neurosurgery - Abstract
Graphene oxide quantum dots (GOQDs) are usually prepared using expensive carbon precursors such as carbon nanotubes (CNT) or graphene under the strong acidic condition, which requires an additional purifying process. Here, we first develop a facile pulsed laser ablation in liquid (PLAL) technique for preparing GOQDs using earth-abundant and low-cost coal as a precursor. Only ethanol and coal are used to produce GOQDs with excellent optical properties. The prepared GOQDs exhibit excellent optoelectronic properties which can be successfully utilized in bioimaging applications.
- Published
- 2019
8. Enzymatic Synthesis of 1, 2-Hexanediol Galactoside by Whole Cells of β-Galactosidase-containing Recombinant Escherichia coli
- Author
-
Kyung-Hwan Jung and Yi-Ok Kim
- Subjects
0106 biological sciences ,Electrospray ,Chromatography ,Silica gel ,Sodium ,chemistry.chemical_element ,medicine.disease_cause ,01 natural sciences ,Galactoside ,0104 chemical sciences ,Adduct ,010404 medicinal & biomolecular chemistry ,Hydrolysis ,chemistry.chemical_compound ,chemistry ,Biochemistry ,010608 biotechnology ,Galactose ,medicine ,Escherichia coli - Abstract
side (HD-G) by a transgalactosylation reaction using β-galactosidase (β-gal)-containing recombinant Escherichia coli cells. The transgalactosylation reaction was carried out under high-lactose conditions for 24 hr. After 12 hr had elapsed, a new spot was identified by thin-layer chromatography (TLC) analysis, and we presumptively designated this new spot as HD-G. The n, we carried out the purification of the presumptive HD-G spot from the reaction mixture by using silica gel chromatography, and its mass was measured by electrospray ionization-mass spectrometry. The purified new spot on the chromatograph was identified a sodium adduct ion ([M+Na] + , m/z = 303.1423) of HD-G. In addition, when purified HD-G was hydrolyzed using commercially available E. coli β-gal, it was observed that a galactose molecule was released from HD-G. That is, it was demonstrated that HD-G is a galactoside derivative of HD. Finally, we confirmed that HD-G was enzymatically synthesized by E. coli β -gal as a new molecular entity. In the future, we plan to determine the minimum inhibitory concentrations of HD-G against different bacterial species. The cytotoxicity of HD-G against human skin cells will also be examined. It is expected hopefully that the galactosylation of HD would improve the functionality of HD-G.
- Published
- 2016
9. Chlorphenesin Galactoside Production using Immobilized β-galactosidase-producing Escherichia coli
- Author
-
Kyung-Hwan Jung
- Subjects
chemistry.chemical_compound ,Chemistry ,medicine ,Alginate bead ,medicine.disease_cause ,Escherichia coli ,Galactoside ,Microbiology - Published
- 2015
10. Ethanol Production from Glycerol Using Immobilized Pachysolen tannophilus During Microaerated Repeated-Batch Fermentor Culture
- Author
-
Kyung-Hwan Jung, Woon Yong Choi, Hye-Geun Cha, Do-Hyung Kang, Hyeon-Yong Lee, and Yi-Ok Kim
- Subjects
Glycerol ,Chromatography ,Ethanol ,biology ,General Medicine ,Cells, Immobilized ,biology.organism_classification ,Diatomaceous Earth ,Applied Microbiology and Biotechnology ,Pachysolen tannophilus ,chemistry.chemical_compound ,chemistry ,Batch Cell Culture Techniques ,Biofuel ,Biofuels ,Fermentation ,Saccharomycetales ,Ethanol fuel ,Ethanol metabolism ,Biotechnology - Abstract
Herein, we established a repeated-batch process for ethanol production from glycerol by immobilized Pachysolen tannophilus. The aim of this study was to develop a more practical and applicable ethanol production process for biofuel. In particular, using industrial-grade medium ingredients, the microaeration rate was optimized for maximization of the ethanol production, and the relevant metabolic parameters were then analyzed. The microaeration rate of 0.11 vvm, which is far lower than those occurring in a shaking flask culture, was found to be the optimal value for ethanol production from glycerol. In addition, it was found that, among those tested, Celite was a more appropriate carrier for the immobilization of P. tannophilus to induce production of ethanol from glycerol. Finally, through a repeated-batch culture, the ethanol yield (Ye/g) of 0.126 ± 0.017 g-ethanol/g-glycerol (n = 4) was obtained, and this value was remarkably comparable with a previous report. In the future, it is expected that the results of this study will be applied for the development of a more practical and profitable long-term ethanol production process, thanks to the industrial-grade medium preparation, simple immobilization method, and easy repeated-batch operation.
- Published
- 2015
11. Enzymatic Synthesis of 2-Phenoxyethanol Galactoside by Whole Cells of ��-Galactosidase-Containing Escherichia coli
- Author
-
Hyang Yeol Lee and Kyung Hwan Jung
- Subjects
Chromatography ,Galactose ,Galactosides ,General Medicine ,beta-Galactosidase ,medicine.disease_cause ,Mass spectrometry ,Applied Microbiology and Biotechnology ,Galactoside ,Hydrolysate ,chemistry.chemical_compound ,chemistry ,Covalent bond ,Yield (chemistry) ,Escherichia coli ,medicine ,Molecule ,Ethylene Glycols ,Biotechnology - Abstract
We investigated whether β-galactosidase (β-gal)-containing Escherichia coli cells could transfer a galactose to 2-phenoxyethanol, resulting in 2-phenoxyethanol galactoside (PE-Gal). PE-Gal was confirmed by liquid chromatography-mass spectrometry. In addition, we also confirmed that a galactose molecule was covalently bonded with PE during thin-layer chromatography analysis of the β-gal hydrolysate of PE-Gal. The yield for PE-Gal synthesis was about 37.5% (weight basis), which was about 7-8 times greater than that of a previous report. In addition, the concentration of β-gal (0.96 U/ml) used in this PE-Gal synthesis was about 20 times less than that in a previous report.
- Published
- 2014
12. Evaluating Carriers for Immobilizing Saccharomyces cerevisiae for Ethanol Production in a Continuous Column Reactor
- Author
-
Hyeon-Yong Lee, Do-Hyung Kang, Yi-Ok Kim, Kyung-Hwan Jung, Woon Yong Choi, and Hye-Geun Cha
- Subjects
Immobilization carrier ,Saccharomyces cerevisiae ,Biology ,Microbiology ,Husk ,chemistry.chemical_compound ,Ethanol fuel ,Chromatography ,Ethanol ,business.industry ,Biosorption ,food and beverages ,Straw ,Sawdust ,Yeast ,Biotechnology ,Infectious Diseases ,chemistry ,Ethanol production ,visual_art ,visual_art.visual_art_medium ,Fermentation ,business ,Continuous column reactor ,Research Article - Abstract
We evaluated a more practical and cost-effective immobilization carriers for ethanol production using the yeast Saccharomyces cerevisiae. Three candidate materials-rice hull, rice straw, and sawdust-were tested for their cell-adsorption capacity and operational durability. Derivatizations of rice hull, rice straw, and sawdust with the optimal concentration of 0.5 M of 2-(diethylamino)ethyl chloride hydrochloride (DEAE · HCl) resulted in > 95% adsorption of the initial yeast cells at 2 hr for DEAE-rice hull and DEAE-sawdust and in only approximately 80% adsorption for DEAE-rice straw. In addition, DEAE-sawdust was found to be a more practical carrier for immobilizing yeast cells in terms of operational durability in shaking flask cultures with two different speeds of 60 and 150 rpm. Furthermore, the biosorption isotherms of DEAE-rice hull, -rice straw, and -sawdust for yeast cells revealed that the Qmax of DEAE-sawdust (82.6 mg/g) was greater than that of DEAE-rice hull and DEAE-rice straw. During the 404-hr of continuous column reactor operation using yeast cells immobilized on DEAE-sawdust, no serious detachment of the yeast cells from the DEAE-sawdust was recorded. Ethanol yield of approximately 3.04 g/L was produced steadily, and glucose was completely converted to ethanol at a yield of 0.375 g-ethanol/g-glucose (73.4% of the theoretical value). Thus, sawdust is a promising practical immobilization carrier for ethanol production, with significance in the production of bioethanol as a biofuel.
- Published
- 2014
13. Ethanol Production from Glycerol using Pachysolen tannophilus in a Surface-aerated Fermentor
- Author
-
Woon-Yong Choi, Kyung-Hwan Jung, Do-Hyung Kang, Yi-Ok Kim, and Hyeon-Yong Lee
- Subjects
chemistry.chemical_compound ,Ethanol ,chemistry ,Biochemistry ,Glycerol ,Yeast extract ,Ethanol fuel ,Fermentation ,Food science ,Aeration ,Yeast ,Fed-batch culture - Abstract
We investigated ethanol production from glycerol after screening of the yeast Pachysolen tannophilus ATCC 32691. For yeast to produce ethanol form glycerol, it is important that aeration is finely controlled. Therefore, we attempted to produce ethanol using a surface-aerated fermentor. When 880 ml of YPG medium (1% yeast extract, 2% peptone, 2% glycerol) was used to produce ethanol, the optimal aeration conditions for ethanol production were a surface aeration rate and agitation speed of 500 ml/min and 300 rpm, respectively. In a fed-batch culture, the maximum ethanol production and the maximum ethanol yield from glycerol (Ye/g) was 5.74 g/l and 0.166, respectively, after 90 hr using the surface-aerated fermentor.
- Published
- 2013
14. Stable Isolation of Phycocyanin from Spirulina platensis Associated with High-Pressure Extraction Process
- Author
-
Hyeon Yong Lee, Woo Seok Choi, Yong Chang Seo, Jong Ho Park, Jin Oh Park, and Kyung-Hwan Jung
- Subjects
DPPH ,Spirulina platensis ,macromolecular substances ,Catalysis ,Article ,Inorganic Chemistry ,Absorbance ,lcsh:Chemistry ,chemistry.chemical_compound ,Bacterial Proteins ,Chromoprotein ,Phycocyanin ,Pressure ,Spirulina ,Physical and Theoretical Chemistry ,high-pressure extraction process ,Molecular Biology ,lcsh:QH301-705.5 ,Spectroscopy ,Spirulina (genus) ,Chromatography ,biology ,Organic Chemistry ,Extraction (chemistry) ,phycocyanin ,General Medicine ,biology.organism_classification ,Computer Science Applications ,Solvent ,chemistry ,lcsh:Biology (General) ,lcsh:QD1-999 ,Yield (chemistry) - Abstract
A method for stably purifying a functional dye, phycocyanin from Spirulina platensis was developed by a hexane extraction process combined with high pressure. This was necessary because this dye is known to be very unstable during normal extraction processes. The purification yield of this method was estimated as 10.2%, whose value is 3%–5% higher than is the case from another conventional separation method using phosphate buffer. The isolated phycocyanin from this process also showed the highest purity of 0.909 based on absorbance of 2.104 at 280 nm and 1.912 at 620 nm. Two subunits of phycocyanin namely α-phycocyanin (18.4 kDa) and β-phycocyanin (21.3 kDa) were found to remain from the original mixtures after being extracted, based on SDS-PAGE analysis, clearly demonstrating that this process can stably extract phycocyanin and is not affected by extraction solvent, temperature, etc. The stability of the extracted phycocyanin was also confirmed by comparing its DPPH (α,α-diphenyl-β-picrylhydrazyl) scavenging activity, showing 83% removal of oxygen free radicals. This activity was about 15% higher than that of commercially available standard phycocyanin, which implies that the combined extraction method can yield relatively intact chromoprotein through absence of degradation. The results were achieved because the low temperature and high pressure extraction effectively disrupted the cell membrane of Spirulina platensis and degraded less the polypeptide subunits of phycocyanin (which is a temperature/pH-sensitive chromoprotein) as well as increasing the extraction yield.
- Published
- 2013
15. Preparation of Corncob Grits as a Carrier for Immobilizing Yeast Cells for Ethanol Production
- Author
-
Choon Geun Lee, Sang-Eun Lee, Kyung-Hwan Jung, Hyeon-Yong Lee, and Do-Hyung Kang
- Subjects
Chromatography ,Ethanol ,biology ,Chemistry ,Saccharomyces cerevisiae ,Biosorption ,General Medicine ,Cells, Immobilized ,Corncob ,biology.organism_classification ,Zea mays ,Applied Microbiology and Biotechnology ,Yeast ,Hydrolysate ,chemistry.chemical_compound ,Bioreactors ,Adsorption ,Ethanolamines ,Biofuels ,Ethanol fuel ,Biotechnology - Abstract
In this study, DEAE-corncobs [delignified corncob grits derivatized with 2-(diethylamino)ethyl chloride hydrochloride (DEAE·HCl)] were prepared as a carrier to immobilize yeast (Saccharomyces cerevisiae) for ethanol production. The immobilized yeast cell reactor produced ethanol under optimized DEAE·HCl derivatization and adsorption conditions between yeast cells and the DEAE-corncobs. When delignified corncob grit (3.0 g) was derivatized with 0.5M DEAE·HCl, the yeast cell suspension (OD600 = 3.0) was adsorbed at >90% of the initial cell OD600. This amount of adsorbed yeast cells was estimated to be 5.36 mg-dry cells/g-DEAE corncobs. The Qmax (the maximum cell adsorption by the carrier) of the DEAE-corncobs was estimated to be 25.1 (mg/g), based on a Languir model biosorption isotherm experiment. When we conducted a batch culture with medium recycling using the immobilized yeast cells, the yeast cells on DEAE-corncobs produced ethanol gradually, according to glucose consumption, without cells detaching from the DEAE-corncobs. We observed under electron microscopy that the yeast cells grew on the surface and in the holes of the DEAEcorncobs. In a future study, DEAE-corncobs and the immobilized yeast cell reactor system will contribute to bioethanol production from biomass hydrolysates.
- Published
- 2012
16. Long-term Repeated-Batch Operation of Immobilized Escherichia coli Cells to Synthesize Galactooligosaccharide
- Author
-
Kyung Hwan Jung, Sang-Eun Lee, and Ji Hyeon Yeon
- Subjects
Inclusion Bodies ,Chromatography ,Galactooligosaccharide ,Escherichia coli Proteins ,Thermophile ,Galactose ,Oligosaccharides ,General Medicine ,Cells, Immobilized ,beta-Galactosidase ,medicine.disease_cause ,Applied Microbiology and Biotechnology ,chemistry.chemical_compound ,Bioreactors ,chemistry ,Biochemistry ,Reactor system ,Microbial enzymes ,Escherichia coli ,medicine ,Glutaraldehyde ,Batch operation ,Operational stability ,Biotechnology - Abstract
In this study, we investigated whether galactooligosaccharide (GOS) can be stably and steadily synthesized using immobilized beta-galactosidase (β-gal) inclusion body (IB)- containing E. coli cells during long-term repeated-batch operation. To improve the operational stability of this enzyme reactor system, immobilized E. coli cells were crosslinked with glutaraldehyde (GA) after immobilization of the E. coli. When we treated with 2% GA for E. coli crosslinking, GOS production continued to an elapsed time of 576 h, in which seven batch runs were operated consecutively. GOS production ranged from 51.6 to 78.5 g/l (71.2 ± 10.5 g/l, n = 7) during those batch operations. In contrast, when we crosslinked E. coli with 4% GA, GOS production ranged from 31.5 to 64.0 g/l (52.3 ± 10.8, n = 4), and only four consecutive batch runs were operated. Although we did not use an industrial β-gal for GOS production, in which a thermophile is used routinely, this represents the longest operation time for GOS production using E. coli β-gal. Improved stability and durability of the cell immobilization system were achieved using the crosslinking protocol. This strategy could be directly applied to other microbial enzyme reactor systems using cell immobilization to extend the operation time and/or improve the reactor system stability.
- Published
- 2012
17. Immobilization of Yeast Pichia stipitis for Ethanol Production
- Author
-
Ji-Eun Lee, Sang-Eun Lee, Kyung-Hwan Jung, Do-Hyung Kang, Eunjin Kim, Joon Ho Choi, Woon Yong Choi, and Hyeon-Yong Lee
- Subjects
Chromatography ,Ethanol ,Materials science ,biology ,Lignocellulosic biomass ,Xylose ,biology.organism_classification ,Hydrolysate ,Yeast ,chemistry.chemical_compound ,chemistry ,Biochemistry ,Biofuel ,Ethanol fuel ,Pichia stipitis - Abstract
In this study, DEAE-cotton [derivatized by 2-(diethylamino)ethyl chloride hydrochloride (DEAE·HCl)] was prepared as a carrier for immobilized Pichia stipitis for ethanol production. When cotton was derivatized with 0.5 M DEAE·HCl, the yeast cell suspension was adsorbed at 100% of the initial cell OD600. The adsorbed yeast cells were estimated to be 101.8 mg-dry cells/g-DEAE-cotton. In particular, when a flask culture using the immobilized yeast cells was conducted in a glucose and xylose-containing medium, the yeast cells on the DEAE-cotton gradually produced ethanol, according to glucose and xylose consumption; the ethanol yield was approximately 0.33 g-ethanol/g-monosaccharide. Because DEAE-cotton was successfully used as a carrier for ethanol production from a glucose and xylose-containing medium, we expect that this bioethanol production process may be used for the bioethanol production process from the hydrolysate of lignocellulosic biomass. All the results of DEAE-cotton were compared with those of DEAE-cellulose as a carrier for immobilization.
- Published
- 2012
18. MgF2-coated porous magnesium/alumina scaffolds with improved strength, corrosion resistance, and biological performance for biomedical applications
- Author
-
Juha Song, Min-Ho Kang, Hyun-Do Jung, Sung Won Kim, Tae-Sik Jang, Kyung-Hwan Jung, Hui-Sun Park, and Hyoun-Ee Kim
- Subjects
Materials science ,Biocompatibility ,Compressive Strength ,Cell Survival ,chemistry.chemical_element ,Spark plasma sintering ,Magnesium Compounds ,Bioengineering ,Biocompatible Materials ,02 engineering and technology ,010402 general chemistry ,Bone tissue ,01 natural sciences ,Hemolysis ,Corrosion ,Cell Line ,Biomaterials ,chemistry.chemical_compound ,Fluorides ,Mice ,X-Ray Diffraction ,Materials Testing ,medicine ,Aluminum Oxide ,Animals ,Humans ,Cell Proliferation ,Magnesium fluoride ,Magnesium ,Metallurgy ,technology, industry, and agriculture ,Hydrogen-Ion Concentration ,equipment and supplies ,021001 nanoscience & nanotechnology ,Biometal ,0104 chemical sciences ,medicine.anatomical_structure ,Compressive strength ,chemistry ,Chemical engineering ,Mechanics of Materials ,Microscopy, Electron, Scanning ,0210 nano-technology ,Porosity - Abstract
Porous magnesium (Mg) has recently emerged as a promising biodegradable alternative to biometal for bone ingrowth; however, its low mechanical properties and high corrosion rate in biological environments remain problematic. In this study, porous magnesium was implemented in a scaffold that closely mimics the mechanical properties of human bones with a controlled degradation rate and shows good biocompatibility to match the regeneration rate of bone tissue at the affected site. The alumina-reinforced Mg scaffold was produced by spark plasma sintering and coated with magnesium fluoride (MgF2) using a hydrofluoric acid solution to regulate the corrosion rate under physiological conditions. Sodium chloride granules (NaCl), acting as space holders, were leached out to achieve porous samples (60%) presenting an average pore size of 240 μm with complete pore interconnectivity. When the alumina content increased from 0 to 5 vol%, compressive strength and stiffness rose considerably from 9.5 to 13.8 MPa and from 0.24 to 0.40 GPa, respectively. Moreover, the biological response evaluated by in vitro cell test and blood test of the MgF2-coated porous Mg composite was enhanced with better corrosion resistance compared with that of uncoated counterparts. Consequently, MgF2-coated porous Mg/alumina composites may be applied in load-bearing biodegradable implants.
- Published
- 2015
19. Galactooligosaccharide Synthesis by Active β-Galactosidase Inclusion Bodies-Containing Escherichia coli Cells
- Author
-
Hye Ji Kim, Kyung-Hwan Jung, Hyeon-Beom Seo, Sang-Eun Lee, and Ji-Hyeon Yeon
- Subjects
Oligosaccharides ,Lactose ,medicine.disease_cause ,Applied Microbiology and Biotechnology ,Hydrolysate ,chemistry.chemical_compound ,Escherichia coli ,medicine ,Beta-galactosidase ,Trisaccharide ,Chromatography, High Pressure Liquid ,Inclusion Bodies ,chemistry.chemical_classification ,Chromatography ,biology ,Galactooligosaccharide ,Temperature ,General Medicine ,Hydrogen-Ion Concentration ,beta-Galactosidase ,Culture Media ,Enzyme ,chemistry ,Biochemistry ,Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization ,Galactose ,biology.protein ,Biotechnology - Abstract
In this study, galactooligosaccharide (GOS) was synthesized using active β-galactosidase (beta-gal) inclusion bodies (IBs)- containing Escherichia coli (E. coli) cells. Analysis by MALDI-TOF (matrix-assisted laser desorption/ionizationtime of flight) mass spectrometry revealed that a trisaccharide was the major constituent of the synthesized GOS mixture. Additionally, the optimal pH, lactose concentration, amounts of E. coli β-gal IBs, and temperature for GOS synthesis were 7.5, 500 g/l, 3.2 U/ml, and 37 °C, respectively. The total GOS yield from 500 g/l of lactose under these optimal conditions was about 32%, which corresponded to 160.4 g/l of GOS. Western blot analyses revealed that β-gal IBs were gradually destroyed during the reaction. In addition, when both the reaction mixture and E. coli β-gal hydrolysate were analyzed by high-performance thin-layer chromatography (HP-TLC), the trisaccharide was determined to be galactosyl lactose, indicating that a galactose moiety was most likely transferred to a lactose molecule during GOS synthesis. This GOS synthesis system might be useful for the synthesis of galactosylated drugs, which have recently received significant attention owing to the ability of the galactose molecules to improve the drugs solubility while decreasing their toxicity. β-Gal IB utilization is potentially a more convenient and economic approach to enzymatic GOS synthesis, since no enzyme purification steps after the transgalactosylation reaction would be required.
- Published
- 2011
20. Enhancement of Saccharification Yield of Ulva pertusa Kjellman by High Pressure Homogenization Process for Bioethanol Production
- Author
-
Do-Hyung Kang, Choon Geun Lee, Woon Yong Choi, Jeong Sub Cho, Geun Pyo Choi, Sang-Eun Lee, Kyung Hwan Jung, Hyeon Yong Lee, Ju Hee Ahn, and Yong Chang Seo
- Subjects
chemistry.chemical_classification ,biology ,Xylose ,Pulp and paper industry ,Hydrolysate ,chemistry.chemical_compound ,Hydrolysis ,chemistry ,Biofuel ,Yield (chemistry) ,Botany ,biology.protein ,Amylase ,Sugar ,Glucan - Abstract
This study was investigated to improve the saccharification yield of Ulva pertusa Kjellman by the high pressure homogenization process. It was found that the high pressure homogenization pretreatment effectively destructed the cell wall structures only by using water. The high pressure homogenization process was operated under various conditions such as 10000, 20000 or 30000 psi with different recycling numbers. The optimal condition was determined as 30000 psi and 2 pass of recycling numbers and the sugar conversion yields were 16.02 (%, w/w) of glucose and 14.70 (%,w/w) of xylose, respectively. In the case of enzymatic treating the hydrolyzates with 5 FPU/glucan of celullase and 100 units/mL of amyloglucosidase, 65.8% of carbohydrates was converted into glucose. Using the hydrolysates of Ulva pertusa Kjellman, 48.7% of ethanol was obtained in the culture S.cerevisiae. These results showed that the high pressure homogenization process could efficiently hydrolyze the marine resource by using only water for bioethanol production.
- Published
- 2011
21. Repeated-Batch Operation of Immobilized β-Galactosidase Inclusion Bodies-Containing Escherichia coli Cell Reactor for Lactose Hydrolysis
- Author
-
Ji Hyeon Yeon and Kyung Hwan Jung
- Subjects
Tris ,Cell ,Lactose ,medicine.disease_cause ,Applied Microbiology and Biotechnology ,Inclusion bodies ,Hydrolysis ,chemistry.chemical_compound ,Bioreactors ,Escherichia coli ,medicine ,Beta-galactosidase ,Inclusion Bodies ,Chromatography ,biology ,Escherichia coli Proteins ,General Medicine ,Enzymes, Immobilized ,beta-Galactosidase ,medicine.anatomical_structure ,Biochemistry ,chemistry ,Batch Cell Culture Techniques ,Biocatalysis ,biology.protein ,Biotechnology - Abstract
In this study, we investigated the performance of an immobilized β-galactosidase inclusion bodies-containing Escherichia coli cell reactor, where the cells were immobilized in alginate beads, which were then used in repeated-batch operations for the hydrolysis of o-nitrophenyl-β-D-galactoside or lactose over the long-term. In particular, in the Tris buffer system, disintegration of the alginate beads was not observed during the operation, which was observed for the phosphate buffer system. The o-nitrophenyl-β-D-galactoside hydrolysis was operated successfully up to about 80 h, and the runs were successfully repeated at least eight times. In addition, hydrolysis of lactose was successfully carried out up to 240 h. Using Western blotting analyses, it was verified that the beta-galactosidase inclusion bodies were sustained in the alginate beads during the repeated-batch operations. Consequently, we experimentally verified that β-galactosidase inclusion bodies-containing Escherichia coli cells could be used in a repeated-batch reactor as a biocatalyst for the hydrolysis of o-nitrophenyl-β-D-galactoside or lactose. It is probable that this approach can be applied to enzymatic synthesis reactions for other biotechnology applications, particularly reactions that require long-term and stable operation.
- Published
- 2011
22. Effects of methanol on cell growth and lipid production from mixotrophic cultivation of Chlorella sp
- Author
-
Jeong-Sub Cho, Juhee Ahn, Woon-Yong Choi, Do-Hyung Kang, Kyung-Hwan Jung, Ga-Bin Kim, Shin Young Lee, Hyeon-Yong Lee, Sung-Ho Oh, Yong-Chang Seo, and Geun-Pyo Choi
- Subjects
Total organic carbon ,Cell growth ,Biomedical Engineering ,Bioengineering ,Biology ,Applied Microbiology and Biotechnology ,chemistry.chemical_compound ,chemistry ,Biodiesel production ,Botany ,Carbon dioxide ,Autotroph ,Methanol ,Food science ,Industrial and production engineering ,Mixotroph ,Biotechnology - Abstract
The marine microalga Chlorella sp. was cultivated under mixotrophic conditions using methanol as an organic carbon source, which may also act to maintain the sterility of the medium for long-term outdoor cultivation. The optimal methanol concentration was determined to be 1% (v/v) for both cell growth and lipid production when supplying 5% CO2 with 450 μE/m2/sec of continuous illumination. Under these conditions, the maximal cell biomass and total lipid production were 4.2 g dry wt/L and 17.5% (w/w), respectively, compared to 2.2 g dry wt/L and 12.5% (w/w) from autotrophic growth. Cell growth was inhibited at methanol concentrations above 1% (v/v) due to increased toxicity, whereas 1% methanol alone sustained 1.0 g dry wt/L and 4.8% total lipid production. We found that methanol was preferentially consumed during the initial period of cultivation, and carbon dioxide was consumed when the methanol was depleted. A 12:12 h (light:dark) cyclic illumination period produced favorable cell growth (3.6 g dry wt/L). Higher lipid production was observed with cyclic illumination than with continuous illumination (18.6% (w/w) vs 17.5% (w/w)), and better lipid production was also obtained under mixotrophic rather than autotrophic conditions. Interestingly, under mixotrophic conditions with 12:12 (h) cyclic illumination, high proportions of C16:0, C18:0, and C18:1 were observed, which are beneficial for biodiesel production. These results strongly indicate that the carbon source is important for controlling both lipid composition and cell growth under mixotrophic conditions, and they suggest that methanol could be utilized to scale up production to an open pond type system for outdoor cultivation where light illumination changes periodically.
- Published
- 2011
23. Effect of initial microstructure on mechanical properties in warm caliber rolling of high carbon steel
- Author
-
Yong-Taek Im, Il-Heon Son, Duk-Lak Lee, Kyung-Hwan Jung, Dong-Kyu Kim, and Y.S. Oh
- Subjects
Austenite ,Toughness ,Materials science ,Cementite ,Mechanical Engineering ,Metallurgy ,Charpy impact test ,Condensed Matter Physics ,Microstructure ,chemistry.chemical_compound ,chemistry ,Mechanics of Materials ,Martensite ,Ferrite (iron) ,General Materials Science ,Pearlite ,Composite material - Abstract
In this study, the effect of initial microstructure on change of mechanical properties was investigated by warm caliber rolling (WCR) of high carbon steel. Experiments were carried out with two different kinds of initial microstructures of pearlite and tempered martensite at the temperature of 500 °C. For comparison, the microstructure of austenite phase obtained from the conventional hot rolling at the temperature of 900 °C up to about 83% of the accumulative reduction in area was assumed to be a reference case. It was found that the WCR provided better mechanical properties in terms of strength and toughness compared to the conventional hot rolling based on experimental results of micro-hardness, tension, and Charpy impact tests. The improvement of strength and toughness was attributed to smaller ferrite grain and dispersed cementite particles with smaller interspacing aligned to the rolling direction after the WCR owing to field emission scanning electron microscopy. The investigated WCR might be useful in obtaining the high strength material with better toughness without adding new alloying elements for industrial applications according to the present investigation.
- Published
- 2011
24. Preparation of Branched Dextran Microspheres of Soluble Interferon Interferon-alpha and its Activity In Vitro and In Vivo
- Author
-
Hua Hong, Jun Tack Hong, Kyung-Hwan Jung, Byeong-Churl Jang, Sun Kyun Yoo, Jeong Rang Jo, and Ji-Hyeon Yeon
- Subjects
Glycidyl methacrylate ,Time Factors ,Alpha interferon ,Applied Microbiology and Biotechnology ,Cell Line ,Plasma ,Animal data ,chemistry.chemical_compound ,In vivo ,Animals ,Humans ,Immunologic Factors ,Drug Carriers ,Chromatography ,Activator (genetics) ,Interferon-alpha ,Dextrans ,General Medicine ,Blood proteins ,Microspheres ,In vitro ,Rats ,Dextran ,Biochemistry ,chemistry ,Delayed-Action Preparations ,Hepatocytes ,Protein Binding ,Signal Transduction ,Biotechnology - Abstract
The study objective was to prepare biodegradable branched dextran microspheres encapsulated with His-tagged interferon-alpha (BDM-hIFN-alpha) and evaluate its activity in vitro and in vivo. The glycidyl methacrylate derivatized dextrans (Dex-GMA) as precursor was primarily synthesized by substituting hydroxyl groups of either the branched or linear type of dextran with GMA. Dex-GMA microspheres loaded with hIFN-alpha was then prepared by the water-in-water emulsion technique. In vitro release and Western blotting experiments demonstrated the retained activity of hIFN-alpha released from branched dextran microspheres at 24 h by inducing phosphorylation of signal transducer and activator transcription-1 (STAT-1), a down-stream effector of IFN-alpha, in HepG2 cells. Animal data further revealed a peak of plasma levels of IFN-alpha in rats injected intravenously with BDM-hIFN-alpha at 10 min post-injection, but a sharp decline at 2 h. High plasma levels of neopterin, a plasma protein induced by IFN-alpha, were also detected in rats injected with BDM-hIFN-alpha at 10 min post-injection. Notably, plasma levels of neopterin remained high at 4 h, but largely declined thereafter.
- Published
- 2011
25. Operation of packed-bed immobilized cell reactor featuring active β-galactosidase inclusion body-containing recombinant Escherichia coli cells
- Author
-
Ji-Hyeon Yeon and Kyung-Hwan Jung
- Subjects
chemistry.chemical_classification ,Packed bed ,Chloroform ,Chromatography ,Biomedical Engineering ,Substrate (chemistry) ,Bioengineering ,medicine.disease_cause ,Applied Microbiology and Biotechnology ,chemistry.chemical_compound ,Enzyme ,chemistry ,Galactose ,medicine ,Industrial and production engineering ,Sodium dodecyl sulfate ,Escherichia coli ,Biotechnology - Abstract
In this study, we developed a packed-bed immobilized cell reactor containing active β-gal (β-galactosidase) inclusion body (IB)-containing Escherichia coli (E. coli) cells in alginate beads. This packed-bed reactor was operated using a substrate feed solution 0.72 ∼ 38.4 mM ONPG (o-nitrophenyl-β-D-galactoside) prepared in Z buffer supplemented with chloroform and 0.1% SDS (sodium dodecyl sulfate). The production rate of ONP (o-nitrophenol) in the reactor containing cells that were incubated with α-MG (α-methyl D-glucospyranoside) or D-fucose after induction was superior to those prepared with cells that were not incubated with α-MG or D-fucose. The ONP production rate was increased proportionally with ONPG concentration in the substrate feed up to a concentration of 38.4 mM. However, as the ONPG concentration was increased in the substrate feed solution, galactose inhibition inside the alginate beads was increased. This most likely occurred due to problems with diffusion. In addition, partial breakage of alginate beads was observed during the later periods of operation. In this study, we demonstrated that active β-gal IB-containing E. coli cells were sustained in the immobilized cell reactor during operation. Particularly, these findings demonstrate the feasibility of using active IBs in an enzymatic reaction without the need for any purification step. In addition, we showed that these IB-containing cells could be directly used in an immobilized reactor.
- Published
- 2010
26. Change in compactness of inclusion bodies of recombinant β-galactosidase expressed in the araBAD promoter system of Escherichia coli
- Author
-
Kyung-Hwan Jung and Ji-Hyeon Yeon
- Subjects
Chemistry ,Biomedical Engineering ,Catabolite repression ,Repressor ,Bioengineering ,medicine.disease_cause ,Trypsin ,Applied Microbiology and Biotechnology ,Inclusion bodies ,law.invention ,chemistry.chemical_compound ,Biochemistry ,law ,medicine ,Recombinant DNA ,Inducer ,Guanidine ,Escherichia coli ,Biotechnology ,medicine.drug - Abstract
We investigated the relevance of the relationship between the compactness of β-galactosidase inclusion bodies (β-gal IBs) and their enhanced enzymatic activity with or without the addition of D-fucose (inducer analog) or methyl α-D-glucopyranoside (α-MG, catabolite repressor) after induction in the araBAD promoter system of Escherichia coli. Experiments conducted to evaluate the solubilization of β-gal IBs in guanidine hydrochloride as well as their trypsin degradation and temperature stability revealed that β-gal IBs expressed in response to the addition of D-fucose or α-MG had a looser structure. Additionally, β-gal IBs expressed when D-fucose or α-MG was added were more quickly solubilized in guanidine hydrochloride or degraded by trypsin-treatment than those produced when these compounds were not added. Moreover, the activity of β-gal IBs expressed when D-fucose or α-MG were added was less stable at various temperatures. Consequently, we deduced that the looser structure of β-gal IBs resulted in enhanced enzymatic activity of β-gal IBs upon addition of D-fucose or α-MG after induction.
- Published
- 2010
27. Long-term repeated fed-batch ethanol fermentation in aerated condition
- Author
-
Do-Hyung Kang, Kyung-Hwan Jung, Hyeon-Beom Seo, Myung Hoon Chung, Ji-Hyeon Yeon, and Hyeon-Yong Lee
- Subjects
Ethanol ,business.industry ,Biomedical Engineering ,Bioengineering ,Ethanol fermentation ,Applied Microbiology and Biotechnology ,Biotechnology ,chemistry.chemical_compound ,chemistry ,Biofuel ,Glycerol ,Ethanol yield ,Ethanol fuel ,Food science ,Aeration ,Industrial and production engineering ,business - Abstract
In this study, we attempted to assess the process stability of long-term fed-batch ethanol fermentation in the absence and presence of aeration (0.33 vvm). To examine the effect of aeration, a long-term repeated fed-batch operation was conducted for 396 h to mimic a long-term industrial bioethanol production process. In this long-term repeated fed-batch ethanol fermentation experiments, withdrawal-fill operation were conducted every 36 h for 10 repeat cycles. The whole operation was stably sustained in a quasi-steady state. The average maximal cell concentration and the average maximal ethanol production during operation were increased by 81.63 and 12.12%, respectively, when aeration was used. In addition, since aeration was carried out, the average ethanol yield slightly decreased by 4.03% and the average specific ethanol production rate decreased by 46.75% during operation. However, the average ethanol productivity increased by 17.53% when aeration was carried out. After 396 h of long-term repeated fed-batch ethanol fermentation, 1,908.9 g of ethanol was cumulatively produced when aeration was used, which was 12.47%, higher than when aeration was not used (1,697.2 g). Meanwhile, glycerol production was greatly decreased during long-term repeated fed-batch ethanol fermentation, in which the glycerol concentration in the culture broth decreased from about 34∼15 g/L. Thus, we can conclude that cell growth was greatly improved by overcoming ethanol inhibition and glycerol production was remarkably decreased when aeration was carried out, although aeration in ethanol fermentation decreased the specific ethanol production rate and ethanol yield.
- Published
- 2010
28. Antimicrobial Effect of Edible Pullulan Film Containing Natural Antimicrobial Material on Cariogenic Bacteria
- Author
-
유상권 ( Sang Guan You ), 정경환 ( Kyung Hwan Jung ), 문성권 ( Sung Kwon Moon ), and 최원석 ( Won Seok Choi )
- Subjects
Nutrition and Dietetics ,food.ingredient ,biology ,food and beverages ,Pullulan ,Propolis ,Grapefruit seed extract ,Antimicrobial ,biology.organism_classification ,Streptococcus mutans ,chemistry.chemical_compound ,food ,chemistry ,Polylysine ,Grape seed extract ,Botany ,Sorbitol ,Food science ,Food Science - Abstract
This study was focused on the development of anticariogenic edible films using pullulan containing grapefruit seed extract (GFSE), polylysine or propolis. According to the result of antimicrobial activity (disc diffusion method) of GFSE, polylysine and propolis against Streptococcus mutans, antimicrobial pullulan film was produced by adding grapefruit seed extract. The optimum combination of pullulan and sorbitol (plasticizer) was 10~15% (w/v) and 40~50% of pullulan (w/w), respectively. Minimum concentration of grapefruit seed extract for growth inhibition of Str. mutans was 50 ppm in medium. Formulation of antimicrobial pullulan films containing grape seed extract was established and these results evidently showed potential for commercial application.
- Published
- 2009
29. High-level production of ethanol during fed-batch ethanol fermentation with a controlled aeration rate and non-sterile glucose powder feeding of Saccharomyces cerevisiae
- Author
-
Hyeon-Yong Lee, Hyeon-Beom Seo, Kyung-Hwan Jung, and Seung Seop Kim
- Subjects
Ethanol ,biology ,business.industry ,Saccharomyces cerevisiae ,Biomedical Engineering ,Bioengineering ,Ethanol fermentation ,Pulp and paper industry ,biology.organism_classification ,Applied Microbiology and Biotechnology ,Corn steep liquor ,Biotechnology ,chemistry.chemical_compound ,chemistry ,Ethanol fuel ,Fermentation ,Industrial and production engineering ,Aeration ,business - Abstract
In this study, we utilized a unique strategy for fed-batch fermentation using ethanol-tolerant Saccharomyces cerevisiae to achieve a high-level of ethanol production that could be practically applied on an industrial scale. During this study, the aeration rate was controlled at 0.0, 0.13, 0.33, and 0.8 vvm to determine the optimal aeration conditions for the production of ethanol. Additionally, non-sterile glucose powder was fed during fed-batch ethanol fermentation and corn-steep liquor (CSL) in the medium was used as an organic N-source. When aeration was conducted, the ethanol production and productivity were superior to that when aeration was not conducted. Specifically, the maximum ethanol production reached approximately 160 g/L, when the fermentor was aerated at 0.13 vvm. These findings indicate that the use of a much less expensive C-source may enable the fermentation process to be directed towards the improvement of overall ethanol production and productivity in fermentors that are aerated at 0.13 vvm. Furthermore, if a repeated fed-batch process in which the withdrawal and fill is conducted prior to 36 h can be employed, aeration at a rate of 0.33 and/or 0.8 vvm may improve the overall ethanol productivity
- Published
- 2009
30. Aeration alleviates ethanol inhibition and glycerol production during fed-batch ethanol fermentation
- Author
-
Hyeon-Beom Seo, Do-Hyung Kang, Ji-Hyeon Yeon, Myung Hoon Jeong, Kyung-Hwan Jung, and Hyeon-Yong Lee
- Subjects
Ethanol ,Chemistry ,Biomedical Engineering ,Bioengineering ,Ethanol fermentation ,Applied Microbiology and Biotechnology ,chemistry.chemical_compound ,Biochemistry ,Biofuel ,Yield (chemistry) ,Glycerol ,Ethanol fuel ,Food science ,Industrial and production engineering ,Aeration ,Biotechnology - Abstract
In this study, we investigated the effects of aeration on ethanol inhibition and glycerol production during fed-batch ethanol fermentation. When aeration was conducted at 0.13, 0.33, and 0.8 vvm, the ethanol productivity, specific ethanol production rate, and ethanol yield in the presence of greater than 100 g/L of ethanol were higher than when aeration was not conducted. In addition, estimation of the parameters (α and β) in a model equation of ethanol inhibition kinetics indicated that aeration alleviated ethanol inhibition against the specific growth rate and the specific ethanol production rate. Specifically, when aeration was conducted, the glycerol yield and specific glycerol production rate decreased approximately 50 and 70%, respectively. Finally, the results of this study indicated that aeration during fed-batch ethanol fermentation may improve the ethanol concentration in the final culture broth, as well as the ethanol productivity.
- Published
- 2009
31. Optimization of an Extracellular Dextranase Production from Lipomyces starkeyi KCTC 17343 and Analysis of Its Dextran Hydrolysates
- Author
-
Jung Hee Shin, Sun-Kyun Yoo, Kyung-Hwan Jung, Joong-Hyun Yeom, Yoon-Hyuck Chang, and Byung Chul Chang
- Subjects
chemistry.chemical_classification ,Dextranase ,Chromatography ,biology ,Hydrolysate ,Enzyme assay ,Hydrolysis ,chemistry.chemical_compound ,Enzyme ,Dextran ,chemistry ,Biochemistry ,Extracellular ,biology.protein ,Fermentation - Abstract
We optimized dextranase culture conditions by batch fermentation using Lipomyces starkeyi KCTC 17343. Furthermore, dextranase was purified by an ultra-membrane, and then dextran hydrolyzates were characterized. Cell growth and dextranase production varied depending on the initial culture pH and temperature. The conditions of optimal dextranase production were met in a pH range of 4-5 and temperature between 25-30℃. At optimal fermentation conditions, total enzyme activity and specific enzyme activity were about 4.85 IU/㎖ and 0.79 IU/g cells, respectively. The specific growth rate was examined to be 0.076 hr-¹. The production of dextranase in culture broth was very stably maintained after mid-log phase of growth. The enzyme hydrolyzed dextran into DP (degree of polymerization) 2 to 8 oligodextran series. Analysis of the composition of hydrolysates suggested that the enzyme produced is an endo-dextranase.
- Published
- 2009
32. Process Optimization of Dextran Production by Leuconostoc sp. strain YSK. Isolated from Fermented Kimchi
- Author
-
Jun-Taek Hong, Jung-Hee Shin, Sung-Paal Yim, Byung Chul Chang, Kyung-Hwan Jung, Seung-Kyun Hwang, Kyung-Suk Hwang, and Sun-Kyun Yoo
- Subjects
chemistry.chemical_compound ,Sucrose ,Dextran ,chemistry ,Biochemistry ,Strain (chemistry) ,Yield (chemistry) ,Yeast extract ,Fermentation ,Response surface methodology ,Food science ,Enrichment culture - Abstract
A bacterium producing non- or partially digestible dextran was isolated from kimchi broth by enrichment culture technique. The bacterium was identified tentatively as Leuconostoc sp. strain SKY. We established the response surface methodology (Box-Behnken design) to optimize the principle parameters such as culture pH, temperature, and yeast extract concentration for maximizing production of dextran. The ranges of parameters were determined based on prior screening works done at our laboratory and accordingly chosen as 5.5, 6.5, and 7.5 for pH, 25, 30, and for temperature, and 1, 5, and 9 g/l yeast extract. Initial concentration of sucrose was 100 g/l. The mineral medium consisted of 3.0 g , 0.01 g , 0.01 g , 0.2 g , 0.01 g NaCl, and 0.05 g per 1 liter deionized water. The optimum values of pH and temperature, and yeast extract concentration were obtained at pH (around 7.0), temperature (27 to ), and yeast extract (6 to 7 g/l). The best dextran yield was 60% (dextran/g sucrose). The best dextran productivity was 0.8 g/h-l.
- Published
- 2008
33. Cadmium specifically induces MKP-1 expression via the glutathione depletion-mediated p38 MAPK activation in C6 glioma cells
- Author
-
Kyung-Hwan Jung, Seong-Il Suh, Sun Kyun Yoo, Sang-Mi Kim, Byeong-Churl Jang, Min-Ho Suh, Jong-Gu Park, Won-Ki Baek, and Hyung Lee
- Subjects
inorganic chemicals ,MAPK/ERK pathway ,Time Factors ,p38 mitogen-activated protein kinases ,chemistry.chemical_element ,Biology ,p38 Mitogen-Activated Protein Kinases ,chemistry.chemical_compound ,Cell Line, Tumor ,Animals ,Protein kinase A ,Protein kinase B ,Cadmium ,Dose-Response Relationship, Drug ,General Neuroscience ,Dual Specificity Phosphatase 1 ,Glioma ,Glutathione ,Rats ,Cell biology ,Enzyme Activation ,Gene Expression Regulation, Neoplastic ,chemistry ,Cell culture ,Intracellular - Abstract
Cadmium is a toxic heavy metal and an environmental pollutant. Mitogen-activated protein kinase (MAPK) phosphatase-1 (MKP-1) is a negative regulator of the family of MAPK. In this study, we investigated the effect of heavy metals on MKP-1 expression in C6 rat glioma cells. Cadmium treatment induced MKP-1 at both protein and mRNA levels while cobalt or manganese treatment did not, suggesting the specificity. Cadmium treatment also depleted intracellular GSH and activated p38 MAPK, JNKs, and AKT. Profoundly, pretreatment with thiol-containing compounds NAC or GSH, but not vitamin E, blocked GSH depletion, 38 MAPK activation and MKP-1 expression by cadmium. Moreover, pharmacological inhibition of p38 MAPK by SB203580 suppressed the cadmium-induced MKP-1. Collectively, these results demonstrate that cadmium specifically induces MKP-1 by transcriptional up-regulation in C6 cells in a mechanism associated with the glutathione depletion-dependent p38 MAPK activation.
- Published
- 2008
34. Magnolol elicits activation of the extracellular signal-regulated kinase pathway by inducing p27KIP1-mediated G2/M-phase cell cycle arrest in human urinary bladder cancer 5637 cells
- Author
-
Sung Soo Park, Keerang Park, Kyung-Hwan Jung, Sung-Kwon Moon, Wun-Jae Kim, Se-Jung Lee, Eun-Jung Kim, and Young-Hwa Cho
- Subjects
G2 Phase ,MAPK/ERK pathway ,medicine.medical_specialty ,Cell Survival ,Apoptosis ,Biochemistry ,Lignans ,chemistry.chemical_compound ,Cyclin-dependent kinase ,Cell Line, Tumor ,Internal medicine ,medicine ,Humans ,Enzyme Inhibitors ,Phosphorylation ,Extracellular Signal-Regulated MAP Kinases ,Cell Proliferation ,Pharmacology ,Cyclin-dependent kinase 1 ,Dose-Response Relationship, Drug ,biology ,Cell growth ,Biphenyl Compounds ,Cell Cycle ,Cell cycle ,Antineoplastic Agents, Phytogenic ,Magnolol ,Cell biology ,Endocrinology ,Urinary Bladder Neoplasms ,chemistry ,Mitogen-activated protein kinase ,biology.protein ,G1 phase ,Cell Division ,Cyclin-Dependent Kinase Inhibitor p27 ,Signal Transduction - Abstract
Magnolol has been reported to play a role in antitumor activity. However, the relevant pathway integrating cell cycle regulation and signaling pathways involved in growth inhibition in cancer cells remains to be identified. In the present study, magnolol treatment of these cells resulted in significant dose-dependent growth inhibition together with apoptosis, G1- and G2/M-phase cell cycle arrest at a 60 microM (IC50) dose in 5637 bladder cancer cells. In addition, magnolol treatment strongly induced p27KIP1 expression, and down-regulated expression of cyclin-dependent kinases (CDKs) and cyclins. Moreover, treatment with magnolol-induced phosphorylation of ERK, p38 MAP kinase, and JNK. Among the pathway inhibitors examined, only PD98059, an ERK-specific inhibitor, blocked magnolol-dependent p27KIP1 expression. Blockade of ERK function consistently reversed magnolol-mediated inhibition of cell proliferation and decreased G2/M cell cycle proteins, but not G1 cell cycle proteins. Furthermore, magnolol treatment increased both Ras and Raf activation. Transfection of cells with dominant negative Ras (RasN17) and Raf (RafS621A) mutant genes suppressed magnolol-induced ERK activity and p27KIP1 expression. Finally, the magnolol-induced reduction in cell proliferation and G2/M cell cycle proteins was also abolished in the presence of RasN17 and RafS621A mutant genes. These data demonstrate that the Ras/Raf/ERK pathway participates in p27KIP1 induction, leading to a decrease in the levels of cyclin B1/Cdc2 complexes and magnolol-dependent inhibition of cell growth. Overall, these novel findings concerning the molecular mechanisms of magnolol in 5637 bladder cancer cells provide a theoretical basis for therapeutic treatment of malignancies.
- Published
- 2008
35. Growth inhibition effect of pyroligneous acid on pathogenic fungus,Alternaria mali, the agent of Alternaria blotch of apple
- Author
-
Kyung-Hwan Jung
- Subjects
Antifungal ,medicine.drug_class ,fungi ,Biomedical Engineering ,Bioengineering ,Alternaria mali ,Biology ,Pathogenic fungus ,biology.organism_classification ,Alternaria ,Applied Microbiology and Biotechnology ,Fungicide ,chemistry.chemical_compound ,Horticulture ,chemistry ,Pyroligneous acid ,Botany ,otorhinolaryngologic diseases ,medicine ,Growth inhibition ,Chemical control ,Biotechnology - Abstract
We investigated the growth inhibition effect of pyroligneous acid on the pathogenic fungus,Alternaria mali, which is known to be the agent of Alternaria blotch of apple plants. Chemical control ofA. mali could be achieved through the use of agrochemical fungicides, while the substitute for agrochemical control is gradually increasing. It was observed that pyroligneous acid exhibited antifungal activity against some plant pathogenic fungi. More specifically, the growth ofA. mali was completely inhibited in pyroligneous acid at a dilution of 1∶32. When its antifungal activity was compared to that of polyoxin B, which is used for the chemical control of Alternaria blotch of apple, it was observed that the antifungal activity of pyroligneous acid diluted at 1∶32 corresponded to 2.0 mg/mL of polyoxin B. Consequently, it is concluded that the diluted pyroligneous acid can substitute for polyoxin B, thereby reducing the use of the agrochemical for the control of Alternaria blotch of apple.
- Published
- 2007
36. Continuous production of recombinant interferon-α in Escherichia coli via the derepression of trp promoter using casamino acid
- Author
-
Kyung-Hwan Jung
- Subjects
Tryptophan ,Casamino acid ,Bioengineering ,Biological activity ,Biology ,medicine.disease_cause ,Applied Microbiology and Biotechnology ,Biochemistry ,Continuous production ,Dilution ,chemistry.chemical_compound ,chemistry ,Cytoplasm ,medicine ,Escherichia coli ,Derepression - Abstract
In this study, the continuous production of trp promoter-directed interferon-α, using recombinant Escherichia coli, was achieved. The trp promoter was derepressed via the depletion of l -tryptophan in the medium, using casamino acid as an organic nitrogen source. The interferon-α production occurring in this condition was confirmed in a flask culture. A medium for continuous operation was also designed and, using that medium, demonstrated that cell concentration and interferon-α production increased proportionally according to glucose concentrations in the reservoir during the continuous culture (dilution rate, D = 0.2 1/h). To examine the optimal condition for continuous production of interferon-α, the continuous operations were carried out at various dilution rates (0.125, 0.254, 0.32, and 0.41 1/h), in which the glucose concentration in the reservoir was 25 g/L. Stable continuous operation was maintained at D = 0.254 1/h, but only for 51 h. The specific interferon-α production (Yp/x) and specific interferon-α production rates (Qp) were estimated at 4.03 ± 1.23 mg/g and 1.02 ± 0.31 mg/g/h, respectively. As these values were far lower than those commensurate with high-level expression or high-cell-density cultures, it was inferred that interferon-α was being expressed as a soluble form. In other words, the interferon-α was expressed as a biologically active form within the cytoplasm. Finally, it was concluded that the recombinant interferon-α could be produced stably on a continuous basis in this study, in which the trp promoter was derepressed simply by including casamino acid in the culture medium.
- Published
- 2006
37. Extended operation of a pressurized 75-L bioreactor for shLkn-1 production by Pichia pastoris using dissolved oxygen profile control
- Author
-
See Hyoung Park, Hyung-Kwon Lim, Sung-Hwan Woo, and Kyung-Hwan Jung
- Subjects
Induction period ,Bioengineering ,Applied Microbiology and Biotechnology ,High-performance liquid chromatography ,Pichia ,Pichia pastoris ,Industrial Microbiology ,chemistry.chemical_compound ,Bioreactors ,Phase (matter) ,Pressure ,Bioreactor ,Glycerol ,Residue (complex analysis) ,Chromatography ,biology ,Methanol ,Monokines ,Macrophage Inflammatory Proteins ,biology.organism_classification ,Recombinant Proteins ,Oxygen ,Solubility ,chemistry ,Chemokines, CC ,Biotechnology - Abstract
In this study, a dissolved oxygen (DO)-stat fed-batch process was conducted in a pressurized 75-L bioreactor, resulting in the production of the short version of human leukotactin-1 (shLkn-1) using Pichia pastoris as the host, with control of the DO-stat profile and an extension of the recombinant shLkn-1 production phase. By regulation of the exhaust-gas valve, we were able to maintain the vessel pressure at up to 120 kPa, in order to overcome DO limitations associated with the use of the DO-stat. The lowest DO value was adjusted by varying the feed pump speed, allowing us to control the DO-stat profile. This principle was successfully applied to both glycerol feeding during the growth phase and methanol feeding for the induction of shLkn-1. The extension of the methanol induction phase to a total of 192 h of culture time resulted in a shLkn-1 concentration of 2.5 g/L, and a total of 102 g of cumulative production. During this extended induction period, the C-terminal residue of shLkn-1 was truncated and this was confirmed by both reverse-phase HPLC and mass spectrometry.
- Published
- 2005
38. Ethanol Production from Glycerol by the Yeast Pachysolen tannophilus Immobilized on Celite during Repeated-Batch Flask Culture
- Author
-
Kyung-Hwan Jung, Do-Hyung Kang, Hye-Geun Cha, Woon Yong Choi, Yi-Ok Kim, and Hyeon-Yong Lee
- Subjects
0106 biological sciences ,Glycerol ,020209 energy ,02 engineering and technology ,01 natural sciences ,Microbiology ,Pachysolen tannophilus ,chemistry.chemical_compound ,Immobilization ,Celite ,010608 biotechnology ,0202 electrical engineering, electronic engineering, information engineering ,Ethanol fuel ,Chromatography ,Ethanol ,biology ,biology.organism_classification ,Yeast ,Research Note ,Infectious Diseases ,chemistry ,Biochemistry ,Ethanol production ,Fermentation - Abstract
We investigated a novel process for production of ethanol from glycerol using the yeast Pachysolen tannophilus. After optimization of the fermentation medium, repeated-batch flask culture was performed over a period of 378 hr using yeast cells immobilized on Celite. Our results indicated that the use of Celite for immobilization of P. tannophilus was a practical approach for ethanol production from glycerol, and should be suitable for industrial ethanol production.
- Published
- 2014
39. Two-step process using immobilized Saccharomyces cerevisiae and Pichia stipitis for ethanol production from Ulva pertusa Kjellman hydrolysate
- Author
-
Do-Hyung Kang, Hyeon-Yong Lee, Woo Yong Choi, Sang-Eun Lee, Kyung-Hwan Jung, and Yi-Ok Kim
- Subjects
chemistry.chemical_classification ,Ethanol ,Xylose ,biology ,Biomass ,General Medicine ,Saccharomyces cerevisiae ,biology.organism_classification ,Applied Microbiology and Biotechnology ,Hydrolysate ,Yeast ,Pichia ,Reducing sugar ,chemistry.chemical_compound ,Ulva ,Bioreactors ,Glucose ,Biochemistry ,chemistry ,Ethanol fuel ,Food science ,Pichia stipitis ,Biotechnology - Abstract
We established a two-step production process using immobilized S. cerevisiae and P. stipitis yeast to produce ethanol from seaweed (U. pertusa Kjellman) hydrolysate. The process was designed to completely consume both glucose and xylose. In particular, the yeasts were immobilized using DEAE-corncob and DEAE-cotton, respectively. The first step of the process included a continuous column reactor using immobilized S. cerevisiae, and the second step included a repeated-batch reactor using immobilized P. stipitis. It was verified that the glucose and xylose in 20 L of medium containing the U. pertusa Kjellman hydrolysate was converted completely to about 5.0 g/l ethanol through the two-step process, in which the overall ethanol yield from total reducing sugar was 0.37 and the volumetric ethanol productivity was 0.126 g/ l/h. The volumetric ethanol productivity of the two-step process was about 2.7 times greater than that when P. stipitis was used alone for ethanol production from U. pertusa Kjellman hydrolysate. In addition, the overall ethanol yield from glucose and xylose was superior to that when P. stipitis was used alone for ethanol production. This two-step process will not only contribute to the development of an integrated process for ethanol production from glucose and xylose-containing biomass hydrolysates, but could also be used as an alternative method for ethanol production.
- Published
- 2013
40. Production of chlorphenesin galactoside by whole cells of β-galactosidase-containing Escherichia coli
- Author
-
Kyung-Hwan Jung, Sang-Eun Lee, and Hyang-Yeol Lee
- Subjects
Lactose ,medicine.disease_cause ,Applied Microbiology and Biotechnology ,Mass Spectrometry ,chemistry.chemical_compound ,Chlorphenesin ,Enzyme Stability ,medicine ,Escherichia coli ,Sugar moiety ,Beta-galactosidase ,Derivatization ,Biotransformation ,Chromatography ,biology ,Chemistry ,Temperature ,Galactose ,General Medicine ,Hydrogen-Ion Concentration ,beta-Galactosidase ,Galactoside ,Biochemistry ,biology.protein ,Chromatography, Thin Layer ,Metabolic Networks and Pathways ,Biotechnology ,Chromatography, Liquid - Abstract
We investigated the transgalactosylation reaction of chlorphenesin (CPN) using β-galactosidase (β-gal)-containing Escherichia coli (E. coli) cells, in which galactose from lactose was transferred to CPN. The optimal CPN concentration for CPN galactoside (CPN-G) synthesis was observed at 40 mM under the conditions that lactose and β-gal (as E. coli cells) were 400 g/l and 4.8 U/ml, respectively, and the pH and temperature were 7.0 and 40oC, respectively. The time-course profile of CPN-G synthesis under these optimal conditions showed that CPN-G synthesis from 40 mM CPN reached a maximum of about 27 mM at 12 h. This value corresponded to an about 67% conversion of CPN to CPN-G, which was 4.47-5.36-fold higher than values in previous reports. In addition, we demonstrated by thin-layer chromatography to detect the sugar moiety that galactose was mainly transferred from lactose to CPN. Liquid chromatography-mass spectrometry revealed that CPN-G and CPN-GG (CPN galactoside, which accepted two galactose molecules) were definitively identified as the synthesized products using β-gal-containing E. coli cells. In particular, because we did not use purified β-gal, our β-gal-containing E. coli cells might be practical and cost-effective for enzymatically synthesizing CPN-G. It is expected that the use of β-gal-containing E. coli will be extended to galactose derivatization of other drugs to improve their functionality.
- Published
- 2013
41. Repeated-batch operation of surface-aerated fermentor for bioethanol production from the hydrolysate of seaweed Sargassum sagamianum
- Author
-
Kyung-Hwan Jung, Hyoen-Yong Lee, Do-Hyung Kang, Ji-Hyeon Yeon, Sang-Eun Lee, and Woon Yong Choi
- Subjects
biology ,Ethanol ,Chemistry ,business.industry ,Sargassum ,Industrial fermentation ,General Medicine ,Xylose ,Pulp and paper industry ,biology.organism_classification ,Applied Microbiology and Biotechnology ,Hydrolysate ,Pichia ,Biotechnology ,chemistry.chemical_compound ,Bioreactors ,Biofuel ,Fermentation ,Bioreactor ,Aeration ,business ,Pichia stipitis - Abstract
In this study, we investigated the feasibility of sustainable long-term bioethanol production from the hydrolysate of a brown seaweed, Sargassum sagamianum. Because the hydrolysate was prepared as a liquid solution using a high-temperature liquefying system, a repeated-batch operation was utilized as the operational strategy for bioethanol production. Additionally, we used surface aeration to improve bioethanol production from the hydrolysate containing C5 monosaccharides such as xylose. In this study, the C5 monosaccharide-utilizable yeast strain Pichia stipitis was used for bioethanol production. Therefore, based on this repeated-batch flask culture, we designed a surface-aerated repeated-batch fermentor culture, in which the aeration was finely controlled at 100 ml/min and delivered into the headspace of a 2.5-l fermentor. When the medium was replaced every 48 h, bioethanol was continuously produced for 200 h under repeated-batch fermentor culture, where the level of bioethanol production was about 9~10 (g/l). Additionally, the bioethanol yield based on the reducing sugar was about 0.386, which was the average value throughout four consecutive cultures and was about 74.5% of the theoretical value. In addition, the bioethanol yield based on quantitative TLC analyses of glucose and xylose was about 0.431, which was the average value throughout four consecutive cultures and was about 84.3% of theoretical value. Consequently, throughout this repeated-batch operation, we demonstrated that it was actually feasible to produce bioethanol from the hydrolysate of seaweed S. sagamianum. In addition, the approach described here is a practical strategy for commercial bioethanol production from seaweed, particularly for finely controlling aeration through surface aeration.
- Published
- 2011
42. Ultraviolet A regulates adipogenic differentiation of human adipose tissue-derived mesenchymal stem cells via up-regulation of Kruppel-like factor 2
- Author
-
Eunsun Jung, Youngsoo Kim, Deokhoon Park, Kyung-Hwan Jung, Kyung-Baeg Roh, Jienny Lee, and Jongsung Lee
- Subjects
MAPK/ERK pathway ,medicine.medical_specialty ,Ultraviolet Rays ,Cellular differentiation ,Kruppel-Like Transcription Factors ,Adipose tissue ,Biology ,AMP-Activated Protein Kinases ,Biochemistry ,chemistry.chemical_compound ,Mice ,Internal medicine ,Adipocyte ,3T3-L1 Cells ,medicine ,Animals ,Humans ,RNA, Small Interfering ,Protein kinase A ,Molecular Biology ,Adipogenesis ,Cell Differentiation ,Mesenchymal Stem Cells ,Cell Biology ,Cell biology ,Up-Regulation ,PPAR gamma ,AP-1 transcription factor ,Endocrinology ,chemistry ,Adipose Tissue ,KLF2 ,Cytokines ,sense organs ,Transcription Factors - Abstract
Adipocyte dysfunction is strongly associated with the development of obesity, which is a major risk factor for many disorders, including diabetes, hypertension, and heart disease. This study shows that ultraviolet A (UVA) inhibits adipogenic differentiation of human adipose tissue-derived mesenchymal stem cells and its action mechanisms. The mRNA levels of peroxidase proliferator-activated receptor (PPAR) γ and CCAAT/enhancer-binding protein α (C/EBPα), but not CCAAT/enhancer-binding protein ((C/EBP) β and δ, were reduced by UVA. Moreover, the mRNA levels of PPAR γ target genes (lipoprotein lipase (LPL), CD36, adipocyte protein (aP2), and liver X receptor α (LXR)) were down-regulated by UVA. Additionally, attempts to elucidate a possible mechanism underlying the UVA-mediated effects revealed that UVA induced migration inhibitory factor (MIF) gene expression, and this was mediated through activation of AP-1 (especially JNK and p42/44 MAPK) and nuclear factor-κB. In addition, reduced adipogenesis by UVA was recovered upon the treatment with anti-MIF antibodies. AMP-activated protein kinase phosphorylation and up-regulation of Kruppel-like factor 2 (KLF2) were induced by UVA. Taken together, these findings suggest that the inhibition of adipogenic differentiation of human adipose tissue-derived mesenchymal stem cells by UVA occurs primarily through the reduced expression of PPAR γ, which is mediated by up-regulation of KLF2 via the activation of MIF-AMP-activated protein kinase signaling.
- Published
- 2010
43. c-Jun N-terminal kinase 1 is required for cordycepin-mediated induction of G2/M cell-cycle arrest via p21WAF1 expression in human colon cancer cells
- Author
-
Kyung-Hwan Jung, Sung-Kwon Moon, Gi-Seong Moon, Wun-Jae Kim, and Se-Jung Lee
- Subjects
Cyclin-Dependent Kinase Inhibitor p21 ,G2 Phase ,Small interfering RNA ,Cell Survival ,Blotting, Western ,Apoptosis ,Enzyme-Linked Immunosorbent Assay ,Biology ,Toxicology ,p38 Mitogen-Activated Protein Kinases ,chemistry.chemical_compound ,Cell Line, Tumor ,Humans ,Immunoprecipitation ,Mitogen-Activated Protein Kinase 9 ,Mitogen-Activated Protein Kinase 8 ,Enzyme Inhibitors ,RNA, Small Interfering ,Extracellular Signal-Regulated MAP Kinases ,Anthracenes ,Cyclin-dependent kinase 1 ,Cordycepin ,Deoxyadenosines ,Cell growth ,Kinase ,c-jun ,Cell Cycle ,General Medicine ,Cell cycle ,Cell biology ,Biochemistry ,chemistry ,Cell culture ,Colonic Neoplasms ,Cell Division ,Food Science - Abstract
Cordycepin (3'-deoxyadenosine) has many anti-cancer properties. However, neither its molecular mechanism nor its molecular targets are well understood. In the present study, we investigated novel molecular mechanisms for the anti-tumor effects of cordycepin in human colon cancer HCT116 cells. After treatment of cells with cordycepin, dose-dependent cell growth inhibition was observed at an IC(50) value of 200muM. Cordycepin treatment resulted in G2/M-phase cell-cycle arrest, which was associated with increased p21WAF1 levels and reduced amounts of cyclin B1, Cdc2, and Cdc25c in a p53-independent pathway. Moreover, cordycepin treatment induced activation of JNK (c-Jun N-terminal kinases). Pretreatment with SP600125, a JNK-specific inhibitor, abrogated cordycepin-mediated p21WAF1 expression, cell growth inhibition, and reduced cell-cycle proteins. Furthermore, JNK1 inhibition by small interfering RNA (siRNA) produced similar results: suppression of cordycepin-induced p21WAF1 expression, decreased cell growth, and reduced cell-cycle proteins. Together, these results suggest a critical role for JNK1 activation in cordycepin-induced inhibition of cell growth and G2/M-phase arrest in human colon cancer cells.
- Published
- 2009
44. Activation of matrix metalloproteinase-9 by TNF-α in human urinary bladder cancer HT1376 cells: The role of MAP kinase signaling pathways
- Author
-
Si-Kwan Kim, Keerang Park, Kyung-Hwan Jung, Sung-Kwon Moon, Se-Jung Lee, Eun Jung Kim, Young-Hwa Cho, Wun-Jae Kim, and Sung Soo Park
- Subjects
Cancer Research ,medicine.medical_specialty ,MAP kinase kinase kinase ,Kinase ,Activating transcription factor ,NF-κB ,General Medicine ,Biology ,Cell biology ,Transactivation ,chemistry.chemical_compound ,Endocrinology ,Oncology ,chemistry ,Internal medicine ,Mitogen-activated protein kinase ,medicine ,biology.protein ,Signal transduction ,Transcription factor - Abstract
The expression of matrix metalloproteinase-9 (MMP-9) has been implicated in tumor invasion and metastasis. In this study, the factors and signaling pathways that are involved in the regulation of the MMP-9 expression were examined in urinary bladder cancer HT1376 cells. Tumor necrosis factor-alpha (TNF-alpha) stimulated the secretion of MMP-9 in HT1376 cells, as shown by zymography and immunoblot analysis. At the level of transcription, TNF-alpha also stimulated 5'-flanking promoter activity of MMP-9. Transcription factor NF-kappaB, AP-1 and Sp-1 binding sites were identified by a gel shift assay to be cis-elements for TNF-alpha activation of the MMP-9 promoter. TNF-alpha activates multiple signaling pathways in HT1376 cells, including the extracellular signal-regulated kinase (ERK1/2), p38 MAP kinase and JNK pathways. Chemical inhibitors, which specifically inhibit each of these TNF-alpha-activated pathways, were used to examine the signaling pathways involved in TNF-alpha-mediated MMP-9 expression. The ERK1/2 inhibitor, U0126 and the p38 MAP kinase inhibitor, SB203580, significantly down-regulated TNF-alpha-induced MMP-9 expression and promoter activity. The transactivation of TNF-alpha-stimulated NF-kappaB, AP-1 and Sp-1 were inhibited by U0126 and SB203580 treatment. In conclusion, the findings of the present study indicate that TNF-alpha induces MMP-9 expression in HT1376 cells by activating transcription factors, which are involved in the ERK1/2- and p38 MAP kinase-mediated control of MMP-9 regulation, namely, NF-kappaB, AP-1 and Sp-1.
- Published
- 2008
45. Sanguinarine induces apoptosis in A549 human lung cancer cells primarily via cellular glutathione depletion
- Author
-
Gy-Young Park, Kyung-Hwan Jung, Jong-Gu Park, Seong-Il Suh, Dae-Kyu Song, Sun Kyun Yoo, Tae Yun Lee, Won-Ki Baek, and Byeong-Churl Jang
- Subjects
Lung Neoplasms ,Cell Survival ,Apoptosis ,Toxicology ,Amino Acid Chloromethyl Ketones ,chemistry.chemical_compound ,Cell Line, Tumor ,Humans ,Sanguinarine ,Gene Silencing ,Enzyme Inhibitors ,RNA, Small Interfering ,Cytotoxicity ,Caspase ,A549 cell ,Benzophenanthridines ,Mitogen-Activated Protein Kinase Kinases ,biology ,Dose-Response Relationship, Drug ,Chemistry ,Dual Specificity Phosphatase 1 ,General Medicine ,Glutathione ,Isoquinolines ,Antineoplastic Agents, Phytogenic ,Caspase Inhibitors ,Cell biology ,Enzyme Activation ,Neuroprotective Agents ,Cell culture ,Caspases ,Cancer cell ,biology.protein ,Drug Screening Assays, Antitumor - Abstract
Sanguinarine is a plant-derived benzophenanthridine alkaloid and has been shown to possess anti-tumor activities against various cancer cells. In this study, we investigated whether sanguinarine induces apoptosis in A549 human lung cancer cells. Treatment of A549 cells with sanguinarine induced apoptosis in a dose- and time-dependent manner. Treatment with sanguinarine led to activation of caspases and MAPKs as well as increased MKP-1 expression. Importantly, pretreatment with z-VAD-fmk, a pan caspase inhibitor suppressed the sanguinarine-induced apoptosis in A549 cells. Moreover, pretreatment with NAC, a sulfhydryl group-containing reducing agent strongly suppressed the apoptotic response and caspase activation to sanguinarine. However, the sanguinarine-mediated cytotoxicity in A549 cells was not protected by pharmacological inhibition of MAPKs or MKP-1 siRNA-mediated knockdown of MKP-1. These results collectively suggest that sanguinarine induces apoptosis in A549 cells through cellular glutathione depletion and the subsequent caspase activation.
- Published
- 2008
46. Improving the yield of soluble 6xHis-tagged interferon-alpha via the addition of repressor of the araBAD promoter system in Escherichia coli
- Author
-
Kyung-Hwan Jung, Ji-Hyeon Yeon, Byeong-Churl Jang, Young-Seo Park, Sung-Hun Kim, and Sun Kyun Yoo
- Subjects
Glycerol ,Blotting, Western ,Alpha interferon ,Repressor ,Bioengineering ,medicine.disease_cause ,Applied Microbiology and Biotechnology ,law.invention ,chemistry.chemical_compound ,law ,Operon ,medicine ,Escherichia coli ,Humans ,Histidine ,Promoter Regions, Genetic ,Polyacrylamide gel electrophoresis ,Electrophoresis, Agar Gel ,Inclusion Bodies ,biology ,Interferon-alpha ,General Medicine ,biology.organism_classification ,Enterobacteriaceae ,Recombinant Proteins ,Repressor Proteins ,Biochemistry ,chemistry ,Solubility ,Recombinant DNA ,Agarose ,Electrophoresis, Polyacrylamide Gel ,Oligopeptides ,Biotechnology - Abstract
The inhibition of inclusion body formation in Escherichia coli by the addition of alpha-D-glucopyranoside or D-fucose after induction improved the purification yield of soluble recombinant interferon-alpha. When D-fucose was added after induction, more soluble 6xHis-tagged interferon-alpha could be purified compared to when methyl alpha-D-glucopyranoside was added. It was shown that, on the basis of 1 mg dry cell weight, 16.6 microg of soluble 6xHis-tagged interferon-alpha was purified when D-fucose was added after induction and 6 ml nickel-chelated agarose gel column was used. This was about 15 times greater than when induction only was performed and 1 ml nickel-chelated agarose gel was used.
- Published
- 2008
47. Inhibition of angiogenesis and angiogenesis-dependent tumor growth by the cryptic kringle fragments of human apolipoprotein(a)
- Author
-
Yeup Yoon, Jung-Sun Yum, Suk-Keun Lee, Doo-Hong Park, Jin-Hyung Ahn, Si-Myung Byun, Soo-Il Chung, Hyun-Kyung Yu, Jihoon Chang, Kyung-Hwan Jung, and Jangseong Kim
- Subjects
Vascular Endothelial Growth Factor A ,Umbilical Veins ,Lung Neoplasms ,Angiogenesis ,Basic fibroblast growth factor ,Gene Expression ,Endothelial Growth Factors ,Biochemistry ,Neovascularization ,chemistry.chemical_compound ,Mice ,Kringles ,Allantois ,Cell Movement ,Neoplasms ,Tumor Cells, Cultured ,Phosphorylation ,Cells, Cultured ,In Situ Hybridization ,Mitogen-Activated Protein Kinase 1 ,Lymphokines ,Mice, Inbred BALB C ,Mitogen-Activated Protein Kinase 3 ,Neovascularization, Pathologic ,Vascular Endothelial Growth Factors ,Chorion ,Recombinant Proteins ,Vascular endothelial growth factor ,medicine.anatomical_structure ,Colonic Neoplasms ,Intercellular Signaling Peptides and Proteins ,Human umbilical vein endothelial cell ,Female ,Fibroblast Growth Factor 2 ,medicine.symptom ,Mitogen-Activated Protein Kinases ,Cell Division ,Angiogenin ,Mice, Nude ,Neovascularization, Physiologic ,Biology ,Kringle domain ,medicine ,Escherichia coli ,Animals ,Humans ,RNA, Messenger ,Fibroblast ,Molecular Biology ,Apolipoproteins A ,Dose-Response Relationship, Drug ,Cell Biology ,Ribonuclease, Pancreatic ,Molecular biology ,Peptide Fragments ,chemistry ,Endothelium, Vascular ,Chickens ,Neoplasm Transplantation - Abstract
Apolipoprotein(a) (apo(a)) contains tandemly repeated kringle domains that are closely related to plasminogen kringle 4, followed by a single kringle 5-like domain and an inactive protease-like domain. Recently, the anti-angiogenic activities of apo(a) have been demonstrated both in vitro and in vivo. However, its effects on tumor angiogenesis and the underlying mechanisms involved have not been fully elucidated. To evaluate the anti-angiogenic and anti-tumor activities of the apo(a) kringle domains and to elucidate their mechanism of action, we expressed the last three kringle domains of apo(a), KIV-9, KIV-10, and KV, in Escherichia coli. The resultant recombinant protein, termed rhLK68, exhibited a dose-dependent inhibition of basic fibroblast growth factor-stimulated human umbilical vein endothelial cell proliferation and migration in vitro and inhibited the neovascularization in chick chorioallantoic membranes in vivo. The ability of rhLK68 to abrogate the activation of extracellular signal-regulated kinases appears to be responsible for rhLK68-mediated anti-angiogenesis. Furthermore, systemic administration of rhLK68 suppressed human lung (A549) and colon (HCT-15) tumor growth in nude mice. Immunohistochemical examination and in situ hybridization analysis of the tumors showed a significant decrease in the number of blood vessels and the reduced expression of vascular endothelial growth factor, basic fibroblast growth factor, and angiogenin, indicating that suppression of angiogenesis may have played a significant role in the inhibition of tumor growth. Collectively, these results suggest that a truncated apo(a), rhLK68, is a potent anti-angiogenic and anti-tumor molecule.
- Published
- 2003
48. Improved Bioethanol Production Using Activated Carbon-treated Acid Hydrolysate from Corn Hull inPachysolen tannophilus
- Author
-
Seung-Seop Kim, Hyeon-Beom Seo, Kyung-Hwan Jung, and Hyeon-Yong Lee
- Subjects
chemistry.chemical_classification ,Arabinose ,Pachysolen tannophilus ,Bioethanol ,Biology ,Xylose ,Microbiology ,Hydrolysate ,chemistry.chemical_compound ,Hydrolysis ,Corn hull ,Infectious Diseases ,chemistry ,Biochemistry ,Biofuel ,medicine ,Acid hydrolysis ,Monosaccharide ,Food science ,Activated-carbon treatment ,Research Article ,Activated carbon ,medicine.drug - Abstract
To optimally convert corn hull, a byproduct from corn processing, into bioethanol using Pachysolen tannophlius, we investigated the optimal conditions for hydrolysis and removal of toxic substances in the hydrolysate via activated carbon treatment as well as the effects of this detoxification process on the kinetic parameters of bioethanol production. Maximum monosaccharide concentrations were obtained in hydrolysates in which 20 g of corn hull was hydrolyzed in 4% (v/v) H2SO4. Activated carbon treatment removed 92.3% of phenolic compounds from the hydrolysate. When untreated hydrolysate was used, the monosaccharides were not completely consumed, even at 480 h of culture. When activated carbon-treated hydrolysate was used, the monosaccharides were mostly consumed at 192 h of culture. In particular, when activated carbon-treated hydrolysate was used, bioethanol productivity (P) and specific bioethanol production rate (Qp) were 2.4 times and 3.4 times greater, respectively, compared to untreated hydrolysate. This was due to sustained bioethanol production during the period of xylose/arabinose utilization, which occurred only when activated carbon-treated hydrolysate was used.
- Published
- 2009
49. Furfural from Pine Needle Extract Inhibits the Growth of a Plant Pathogenic Fungus,Alternaria mali
- Author
-
Sun Kyun Yoo, Kyung-Hwan Jung, Sung-Kwon Moon, and Ung Soo Lee
- Subjects
integumentary system ,Chlorothalonil ,biology ,fungi ,Alternaria mali ,Pathogenic fungus ,Note ,Furfural ,biology.organism_classification ,Dry distillation ,Alternaria ,Microbiology ,Plant disease ,chemistry.chemical_compound ,Infectious Diseases ,chemistry ,Botany ,Alternaria blotch ,Extraction methods ,Antifungal activity ,Food science ,Pine needle extract - Abstract
The antifungal effect of pine needle extract prepared by a distinguishable extraction method and the dry distillation method, was examined. The effect of this extract itself was insignificant. The chemical components of pine needle extract were then investigated by gas chromatographic analysis, and four chemical components, acetol, furfural, 5-methyl furfural, and terpine-4-ol, were identified. The antifungal effects of those four chemical components against Alternaria mali (A. mali), an agent of Alternaria blotch of apple, were then examined. It was observed that the minimum inhibitory concentrations (MICs) were 6.25, 0.78, 0.78, and 12.5 (mg/ml) of acetol, furfural, 5-methyl furfural, and terpine-4-ol, respectively. MICs of furfural and 5-methyl furfural had the same order of magnitude as that of an antifungal agrochemical, chlorothalonil. Although furfural itself can not be completely substituted for an antifungal agrochemical, a partial mixture of furfural and antifungal agrochemical may be used as a substitute. The use of agrochemicals for the prevention of plant disease caused by pathogenic fungus such as A. mali could be partially reduced by the application of this mixture.
- Published
- 2007
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.