Search

The development of highly stable radiocopper complexes is one major challenge that seeks to further improved radiopharmaceuticals for medicinal applications. In many cases, radiocopper complexes suffer the fate of dissociation in vivo which is contributed to loss of the radionuclide resulting amongst others in an unspecific accumulation in non-target tissues and thus in poor target-to-background ratios. The kinetic lability has been addressed as major issue for transchelation or dissociation in vivo. Valuable information of kinetic inertness can be derived from non-physiological and non-radiotracer conditions e.g., ligand or metal ion challenge experiments, acid-assisted dissociation studies. Serum stability experiments are more suitable, since they are associated with in vivo conditions. Usually, the method of choice to measure the kinetic inertness involves a time-consuming radio-HPLC procedure. In contrast, we describe two reliable in vitro assays using standard gel electrophoresis techniques which provide a timesaving work-flow for measuring simultaneously a variety of copper-containing chelates. With this procedure, different radiocopper chelates can be evaluated and compared concerning their kinetic inertness using protein challenge assays. Moreover, both experiments are transferable not only to newly designed chelates, but also to conjugates containing targeting molecules such as peptides or proteins.

Two-dimensional gel electrophoresis (2DE) separating proteins on the basis of their pI and molecular mass remain the best available technique for protein separation and characterization to date. But due to several limitations, including streak formation in IEF gels, partial solubility of proteins, expensive running conditions and relatively longer time taken, a simple urea-SDS-2D polyacrylamide gel electrophoresis (US2DE) is described here. The system is reasonably sensitive, cost effective with good reproducibility. The method described in this paper employs a chaotropic agent, urea, in the first dimension and sodium dodecyl sulphate (SDS), like conventional system, in the second dimension with an addition of polyacrylamide to screen the liver proteome of healthy and chemically induced fibrotic rats. The system separates the protein on the basis of chargeto- mass ratio and clearly demonstrates differential expression in the liver protein repertoire of healthy and fibrotic rats. Moreover, the present system, like other 2D electrophoretic procedures revealed at least 22 novel spots in the investigated tissues. The technique may be utilized for comprehensive proteome screening of any biological sample and would provide an overview to narrow down the candidate proteins or biomarkers.

Electrophoretic examination of dissociated haemocyanin subunits from a number of amphipod, decapod and isopod crustaceans supports the hypothesis that subunit composition is species-specific, despite marked within-species variation in many species. General patterns of heterogeneity on native PAGE gels were also evident between groupings within the Amphipoda. Gammarid amphipods could be split into two groups; one characterised by a high degree of heterogeneity and the other by a low degree of heterogeneity. The talitrid amphipods generally displayed a low degree of heterogeneity similar to, although still distinct from, the second gammarid category. Haemocyanin from the Hyalidae, a family allied to the talitrids was highly heterogeneous, similar to the first gammarid group and unlike the talitrids. Isopod haemocyanin banding patterns were more similar to one another than to any of the amphipod or decapod species examined. In general, the molecular weights of the amphipod Hcs tended to be greater than those of the isopods, with the decapods being lowest of all. It is suggested that Hc subunit heterogeneity may be a useful tool for investigating speciation and speciation events, and for reliably separating very closely-related species (e.g. Gammarus spp.), purely on the basis of their Hc subunit compositions.

Arthrobotrys amerospora ATCC 34468 produced glucoamylase in a medium containing maize starch as carbon source. On native PAGE, crude glucoamylase showed three isoenzymes which were designated as Glu I, Glu II, Glu III according to their electrophoretic mobility. These were purified by column chromatography techniques. The energy of binding for each glucoamylase was calculated using Hiromi's kinetic based calculation. At subsite 1, the binding energies for Glu I, II and III were found to be negative.

Many proteins, including antibacterial peptides in the hemolymph, are induced by bacterial infections. We found two bacterially inducible carboxylesterases (CEs) in the hemolymph of the silkworm, Bombyx mori. CEs Est-1 and 2 were induced by lipopolysaccharide injection after 6 hours as well as E. coli infection. We found that bacterially inducible CEs clearly differed from noninducible CEs, including juvenile hormone esterases, in pI values, migration on analytical native PAGE, and inhibitor sensitivity. We are now studying the features and functions of these CEs.

Oligomerization of complete and incomplete combinations of rat muscle-type nicotinic acetylcholine receptor (nAChR) subunits in Xenopus oocytes was studied by blue native PAGE and compared with acetylcholine-activated current in these cells. The rank order of expression level judged by current was alpha 1 beta 1 gamma deltaalpha 1 beta 1 gammaalpha 1 beta 1 deltaalpha 1 gamma deltaalpha 1 deltaalpha 1 gamma. alpha 1 and alpha 1 beta 1 were not functional. Protein complexes incorporating a heptahistidyl-tagged alpha 1 subunit were chromatographically purified from digitonin extracts of oocytes and resolved by blue native PAGE. In the absence of any co-expressed nAChR subunit, the majority of alpha 1 formed aggregates. Co-expression of beta 1 had no effect on alpha 1 aggregation, whereas both gamma and delta diminished alpha 1 aggregation in favor of discrete oligomers: alpha 1 formed tetramers together with gamma and dimers, trimers, and tetramers together with delta. When alpha 1 gamma was complemented with beta 1 to form a functional alpha 1 beta 1 gamma receptor, a small amount of a pentamer was found besides a prominent alpha 1-His7 beta 1 gamma trimer. Expression of the functional alpha 1 beta 1 delta receptor yielded marked amounts of a pentamer besides dimers and trimers. These results are discussed in terms of the assembly model of Green and Claudio (Cell 74, 57-69, 1994), substantiating that blue native PAGE is suited for the investigation of ion channel assembly.

Glutamic acid–salicylaldehyde Schiff-base metal complexes are bound into bovine serum albumin (BSA), which afforded BSA binding Schiff-base metal complexes (BSA-SalGluM, M Cu, Co, Ni, Zn). The BSA binding metal complexes were characterized by UV–vis spectra and Native PAGE. It showed that the protein structures of BSA kept after coordinating amino acid Schiff-bases metal complexes. The effect of the antioxidant activity was investigated. The results indicate that the antioxidant capacity of BSA increased more than 10 times after binding Schiff-base metal complexes.

Based on a differential pre-screening of 44 white-rot fungi on a lignocellulose-supplemented minimal medium, four basidiomycetes were selected for further study: Ganoderma lucidum, Polyporus brumalis, Polyporus ciliatus and Trametes versicolor. Only G. lucidum was able to grow vividly on malt extract or minimal media supplemented with alkali lignin. When grown on malt extract or minimal medium supplemented with lignocellulose (sugar cane bagasse), the crude G. lucidum protein extract exhibited high laccase activity, ∼3 U/mL toward syringaldazine. This activity was 13–17 fold higher than the corresponding activities of the crude protein extracts of P. brumalis, P. ciliatus and T. versicolor. Native PAGE electrophoresis of the crude G. lucidum extract confirmed the presence of an active laccase. The G. lucidum laccase had a molecular weight of ∼62.5 kDa, and a Km value of 0.107 mM (determined on ABTS). A partial amino acid sequence analysis of four short de novo sequenced peptides, defined after trypsin digest analysis using MALDI-TOF MS/MS analysis, revealed 64–100% homology to sequences in related laccases in the UniProt database, but also indicated that certain sequence stretches had low homology. Addition of the laccase-rich G. lucidum broth to lignocellulosic biomass (pretreated sugar cane bagasse) together with a state-of-the-art cellulase enzyme preparation (Cellic™CTec1) produced significantly increased cellulolytic yields, which were also better than those obtained with a T. versicolor laccase addition, indicating that the laccase from G. lucidum has unique properties that may be momentous in lignocellulosic biomass conversion.

Seasonal weight loss (SWL) is the most important limitation to animal production in tropical and Mediterranean regions, conditioning commercial producer’s incomes and the nutritional status of rural communities (Almeida et al., 2006; Almeida and Cardoso, 2008). It is of outmost importance to produce strategies to oppose adverse effects of SWL. Breeds that have evolved in harsh climates have acquired a tolerance to SWL through selection. Most of the factors determining such ability are related to biochemical metabolic pathways and are likely important biomarkers to SWL. The objective of the present work is to establish a Blue-Native protocol to separate and study mitochondrial protein complexes isolated from mammary glands, as a tool to investigate molecular markers of tolerance to SWL in sheep (Ovis aries) as a model for other dairy ruminants, particularly goats. After mitochondrial isolation, protein complexes were solubilized with different detergent concentrations. The protein profiles were thereafter assessed by BN-PAGE.

Three types of cysteine synthase (CSase, EC 4.2.99.8) isozymes were purified from spinach leaves. Each isozyme was isolated to homogeneity by preparative PAGE. These isozymes were revealed to have different primary structures by amino-acid and proteinase digestion analyses, respectively. The enzymes designated as CSase 1, CSase 2 and CSase 3 with reference to the mobility on native PAGE were characterized with respect to physicochemical and enzymatic properties, and it was found that those enzymes had similar properties. It was also found that CSase 1 could be attributed to chloroplasts.

Metalloproteomics is a rapidly developing field of science that involves the comprehensive analysis of all metal-containing or metal-binding proteins in a biological sample. The purpose of this review is to offer an overview of the research involving Metal Isotope native RadioAutography in Gel Electrophoresis (MIRAGE), a powerful new method to visualize and study the proteome of a particular metal ion. MIRAGE involves four steps: i) labelling of target proteins with a radioisotope; ii) separation of intact holo-proteins using native isoelectric focusing (1D) combined with Blue Native PAGE (2D); iii) spot visualization and quantification using autoradiography; and iv) protein identification by tandem mass spectrometry. MIRAGE Investigations of the soluble Cu, Zn, and Fe metalloproteomes of Escherichia coli, and of the soluble Mo and W proteomes of the hyperthermophilic archaeon Pyrococcus furiosus are reviewed.

The expression and distribution of digestive cellulases along the midgut of Cerambyx cerdo larvae were analyzed for the first time and are presented in this article. Four groups of larvae were examined: larvae developed in the wild; larvae taken from the wild and successively reared on an artificial diet based on polenta; and larvae hatched in the laboratory and reared on two different artificial diets. Seven endocellulase and seven ?-D-glucosidase isoforms were detected in all midgut extracts of C. cerdo with a zymogram after native PAGE. We observed that C. cerdo larvae are capable of producing cellulase isoforms with different PAGE mobilities depending on the nutrient substrate. From our findings it can be assumed that, depending on the distribution of endocellulase and ?-D-glucosidase, cellulose molecules are first fragmented in the anterior and middle midgut by endo-?-1,4-glucanase; subsequently, the obtained fragments are broken down by ?-D-glucosidase mostly in middle midgut.

This paper is a study on the distribution of the denatured whey proteins and kappa-casein in soluble and micelle-bound complexes in heat treated caprine and bovine milk (90 degrees C, 10 min) at natural pH (6.71). Proteins were fractionated using fractionation technique based on renneting and were analysed by three electrophoretic techniques: native PAGE, SDS-PAGE under reducing and non-reducing conditions. Lower than 3% of the total beta-LGs remained stable after heat treatment of both milk species, but bovine alpha-LA was more heat stable than its counterpart in caprine milk (29.6% against 3.82%). Denatured caprine whey proteins (>95%) were part of micelle-bound complexes whereas soluble complexes were not observed. Conversely, about 30% of denatured bovine whey proteins were involved in soluble complexes. About 24.2% of total kappa-CN was included into complexes formed in heat-treated bovine milk whereas in heat-treated caprine milk this percentage is about three times higher. Caprine micelle-bound complexes, apart from whey proteins and kappa-casein included also beta-casein and alpha(s2)-casein, which were not found in their bovine counterparts. This knowledge could be very useful in understanding the differences in technological-functional properties of caprine and bovine milk and to enable better control of dairy processes.

Classically, DIGE is carried out on the basis of two-dimensional (2D) IEF/SDS PAGE. This allows comparative analyses of large protein sets. However, 2D IEF/SDS PAGE only poorly resolves hydrophobic proteins and is not compatible with native protein characterizations. Blue native PAGE represents a powerful alternative. Combined with CyDye labeling, blue native DIGE offers several useful applications like quantitative comparison of protein complexes of related protein fractions. Here we present a protocol for fluorophore labeling of native protein fractions for separation by blue native PAGE.

We describe a procedure to detect protein binding to SSB by polyacrylamide gel electrophoresis under non-denaturing conditions. As an example, we show the interaction of Thermus thermophilus (Tth) SSB with its cognate RecO protein. The interaction is detected as decay of the band corresponding to SSB by addition of RecO. We also demonstrate analysis of the RecO-RecR interaction as another example of this method.

Polyacrylamide gel electrophoresis was performed on ultrapasteurized liquid whole egg (LWE), which was either homogenized or unhomogenized and heated at 64, 68, or 72 C each for 30, 60, or 95 s. Native PAGE was used to determine the effect of ultrapasteurization in combination with homogenization on LWE protein. The α-livetin band was absent at 72 C for 60 and 95 s processing times but remained present at the 30-s treatment time at 72 C and for all processing times at 64 and 68 C. Protein bands of the globulin/β-livetin and ovotransferrin/γ-livetin fractions appear to have faded in all heat-treated samples in comparison with the unheated samples, reflecting their heat instability. Homogenization had no effect on the presence of protein bands identified by PAGE.

Native-PAGE (polyacrylamide gel electrophoresis) was used for the simultaneous qualitative and quantitative analysis of bovine milk adulteration in caprine and ovine milk using whole milk samples as well as their whey protein fraction Quantification was based on measuring band intensity of bovine beta-lactoglobulins in all milk mixtures and bovine alpha-lactalbumin in caprine/bovine milk blends Linear relationships were established between the band intensity of bovine beta-lactoglobulins and alpha-lactalbumin vs volume percentage of added bovine milk in all milk analysed with the correlation coefficient from 0 9950 to 0 9998 These correlations enabling the quantification of bovine milk percentage within the wide range from 3% or 5% to 90% in caprine/bovine and ovine/bovine milk blends respectively The differences between the actual percentages of bovine milk present in the adulterated milk samples and those calculated using the regression lines were less than or equal to 5% for all samples This method offers a rapid determination combined with unequivocal identification of the bovine whey proteins in almost every caprine/bovine or ovine/bovine milk mixtures

Preface 1. The Role of Antioxidants in Human Health Saikat Sen and Raja Chakraborty 2. Pathophysiological Implications of Altered Redox Balance in HIV/AIDS Infection: Diagnosis and Counteract Interventions L. Gil del Valle, Ph.D. 3. Thermodynamics of Free Radical Reactions and the Redox Environment of a Cell Klaudia Jomova and Marian Valko 4. Oxidative Stress in the Metabolism of Estrogens Leading to Cancer Initiation: Prevention by Specific Antioxidants Eleanor G. Rogan and Ercole L. Cavalieri 5. Polyphenol Compounds as Antioxidants for Disease Prevention: Reactive Oxygen Species Scavenging, Enzyme Regulation, and Metal Chelation Mechanisms in E. coli and Human Cells Hsiao C. Wang and Julia L. Brumaghim 6. DNA-Protective Mechanisms of Glutathione Intervention in Catechol-Mediated Oxidative DNA Damage in the Presence of Copper(II) Ions Maria Hepel, Magdalena Stobiecka, Janet Peachey, and Jeremiah Miller 7. Antioxidant Effectiveness in Preventing Paraquat-Mediated Oxidative Dna Damage in the Presence of H2O2 Magdalena Stobiecka, Amanda Prance, Kaitlin Coopersmith, and Maria Hepel 8. Artificial Nanoparticle Antioxidants Erica Sharpe, Daniel Andreescu, and Silvana Andreescu 9. Cerium Oxide Nanoparticles for the Treatment of Neurological Oxidative Stress Diseases A. Y. Estevez and J. S. Erlichman 10. Detection of Superoxide and Hydrogen Peroxide from Living Cells Using Electrochemical Sensors Szilveszter Gaspar 11. Peroxynitrite and Nitroxidative Stress: Detection Probes and Micro-Sensors. A Case of a Nanostructured Catalytic Film Serban F. Peteu, Saleem Banihani, Mutha M. Gunesekera, Pubudu Peiris, Oana A. Sicuia, and Mekki Bayachou 12. Blue Native PAGE and Mass Spectrometry as an Approach for the Investigation of Stable and Transient Protein-Protein Interactions Alisa G. Woods, Izabela Sokolowska, Rama Yakubu, Melissa Butkiewicz, Martin LaFleur, Christopher Talbot, and Costel C. Darie 13. Mass Spectrometry for Proteomics-Based Investigation of Oxidative Stress and Heat Shock Proteins Izabela Sokolowska, Alisa G. Woods, Jessica Wagner, Jeannette Dorler, Kelly Wormwood, Johannes Thome, and Costel C. Darie Editors' Biographies Author Index Subject Index

Three types of monohydroxybenzoate oxygenase, salicylate 5-oxygenase (SAL5O) forming gentisate from salicylate, m-hydroxybenzoate 6-oxygenase (MHB6O) forming gentisate from m-hydroxybenzoate, and p-hydroxybenzoate 3-oxygenase (PHB3O) forming protocatechuate from p-hydroxybenzoate, were purified from a cell-free extract of Rhodococcus erythropolis S-1, a Gram-positive bacterium. Each purified enzyme was homogenous on native PAGE. Each enzyme was a tetramer having identical subunits, a flavoporotein containing FAD, and a NADH-dependent monooxygenase. The three enzymes were much alike in general enzymatic properties, but very different in substrate specificity.

SDS normally is strictly avoided during Blue native (BN) PAGE because it leads to disassembly of protein complexes and unfolding of proteins. Here, we report a modified BN-PAGE procedure, which is based on low-SDS treatment of biological samples prior to native gel electrophoresis. Using mitochondrial OXPHOS complexes from Arabidopsis as a model system, low SDS concentrations are shown to partially dissect protein complexes in a very defined and reproducible way. If combined with 2-D BN/SDS-PAGE, generated subcomplexes and their subunits can be systematically investigated, allowing insights into the internal architecture of protein complexes. Furthermore, a 3-D BN/low-SDS BN/SDS-PAGE system is introduced to facilitate structural analysis of individual protein complexes without their previous purification.

INTRODUCTIONMany polypeptides do not perform their functions as single autonomous units in vivo. Instead, multiple polypeptides associate to form higher molecular mass structures. Blue-native polyacrylamide gel electrophoresis (BN-PAGE) allows a range of the major protein complexes involved in such protein-protein interactions to be visualized simultaneously and in a single experiment. When combined with a second dimension of sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), the BN/SDS-PAGE procedure can resolve the complexes according to their molecular weight, as well as the subunits within each complex, according to the molecular weights of the subunits. Similarly, used in conjunction with differential in-gel electrophoresis (DIGE), it can accurately quantify changes in protein complex abundance or subunit composition between different samples, or between different complexes within the same sample. The following basic protocol describes sample preparation and gel casting for the first (BN-PAGE) and second (SDS-PAGE) dimensions. Variants are presented with and without DIGE labeling, along with the additional steps required for the fluorescence DIGE technique.

In the telomere region, T-loop structure is thought to participate in protecting chromosome ends. Although the tetraplex structure, called G-quadruplex, is suggested to form in the same region, the relationship between these two structures are less discussed. Here we designed the long lariat formation using G-quadruplex structure. The structural property was characterized by means of CD spectroscopy, FRET experiment, and native PAGE analysis. Because this lariat formation contains both loop structure and tetraplex structure, it can be a key structure linking T-loop structure to G-quadrurplex structure.

Lipolytic enzymes from marine microbes have been the focus of intense and growing research. The bioluminescencebacterium Vibrio fischeri was produced lipase enzyme when the medium contained specific substrate. The lipase waspurified from the concentrated culture supernatant. The most active fractions were obtained using the technique ofprecipitation with ammonium sulphate. The precipitated fraction was purified by desalting and ion exchangechromatography. The purified active fraction exhibiting final specific activity of 121U/mg and characterized; theoptimum pH was likely between 7 to 8, the optimum temperature was 30°C and about 80 % of activity at 5°C. Theenzyme was very stable at the pH 8, at the temperature 30°C. The enzyme was monomeric protein having molecularmass of 57 KDa estimated by native PAGE assay.

The organization of human telomeric DNA is of intense interest because of its role in aging, cancer research and bioanalytical applications. The Htelom sequence 5′-G 3 (T 2 AG 3 ) 3 -3′ has been use to prepare two pyrene-modified fluorescence probes with three- and six-carbon linkers: Py-Htelom-Py(C3) and Py-Htelom-Py(C6), respectively. Results of the circular dichroism (CD), native PAGE, steady-state fluorescence, and anisotropy measurements of sodium and potassium quadruplex formation by these pyrene-modified conjugates are presented and discussed in order to clarify which conformation facilitates or renders the pyrene/pyrene or G-tetrad/pyrene stacking interaction. The CD spectra and native PAGE images suggested that conjugation of pyrene moieties has negligible effect on the folding properties of Htelom oligonucleotide. CD melting profiles and thermodynamic parameters revealed that both sodium and potassium quadruplexes are stabilized by the anchoring of pyrene tags with potassium ion being more effective than its sodium counterpart. Monomer emission of pyrene dominated in all investigated systems with fluorescence intensity being sensitive to the nature and concentration of cation and this phenomenon was attributed to the quenching processes and to the particular topologies of sodium and potassium quadruplexes. Strong quenching observed in the presence of KCl was attributed to the peculiarity of the potassium hybrid-type quadruplex, which enables effective stacking of pyrene moieties on the exposed guanine tetrads, thus facilitating static or electron transfer quenching. Plausibility of stacking interactions between pyrene and G-tetrad in a hybrid-type potassium quadruplex was further supported by the anisotropy measurements and molecular modeling results.

Aldehyde oxidase (AO) is a homodimer with a molecular weight of 300 kDa. To clarify the reasons for the well-known differences in rat strains, we set out to study the relationship between AO activity and the expression levels of its dimer. AO-catalyzed 2-oxidation activity of (S)-RS-8359 was measured in liver cytosols from ten rat strains. The expression levels of AO dimeric protein were evaluated by the native-PAGE/Western blot. Rat strains with low AO activity showed only a monomer, whereas strains with high activity overwhelmingly exhibited a dimer. Exceptionally, one strain in the high AO activity group displayed complex mixed expression patterns of low and high AO activity groups. However, there was a good relationship between AO activity and the expression levels of a dimer, but not of a monomer. The results suggest that rat strains with low AO activity lack the ability to produce a dimer necessary for catalytic activity, and AO differences in rat strains should be discussed in terms of the expression levels of the dimer itself.

Background: Human serum adiponectin exists in 3 multimer forms: high molecular weight (HMW), middle molecular weight, and low molecular weight (LMW), with some of the latter bound to albumin (Alb)-LMW. Some studies have suggested that adiponectin crosses the blood–brain barrier and plays a central role in energy homeostasis. Methods: To determine cerebrospinal fluid (CSF) adiponectin at extremely low concentrations, we modified the protocol of the ELISA system used to assay serum adiponectin. The 3 multimers of adiponectin were measured separately by pretreating CSF with 2 proteases. We measured the CSF adiponectin concentrations in anonymous human samples (n = 19). The molecular sizes of adiponectin in CSF pretreated with proteases or untreated were determined by use of native PAGE and immunoblotting. Results: The ELISA system measured adiponectin in the range of 1.0–167 μg/L. The between-assay imprecision estimates (CVs) were 6%–17% for the 3 forms. The mean total CSF adiponectin concentration (7.2 μg/L) was ∼1/1000 of the mean concentration in serum. Unlike serum adiponectin, the LMW and Alb-LMW forms predominated in all of the CSF samples. Immunoblotting analysis revealed that most LMW forms were bound to Alb, although the HMW form was detected in some samples. Conclusions: The modified ELISA system measures the 3 multimers separately and is sufficiently sensitive to measure adiponectin in CSF.

The Deriphat 2-DE was used to visualize polyphenol oxidase (PPO) isoforms of Moscato and Prosecco grape extracts, partially purified and characterized. Catecholase has similar values in the two varieties, whereas Moscato cresolase data are almost 54% higher. In the first dimension, the PPO of both varieties may be detected by SDS-PAGE, but native PAGE (N-PAGE) gave negative results. For this reason, the samples were solubilized in the zwitteronic detergent Deriphat, which was also included in the gel and the cathodic buffer. Deriphat migrated together with the cathodic buffer, maintaining protein solubility and revealing the PPO profiles of Moscato and Prosecco extracts in native conditions. The combination of Deriphat-PAGE (D-PAGE) and SDS-PAGE (2-DE) also resulted in improved separation efficiency in resolving PPO and specialized stains in evaluating PPO activities. The control, represented by IEF for the first-dimensional separation, had a lower number of spots, demonstrating the higher capacity of Deriphat 2-DE to isolate PPO isoforms from grape extracts. The Deriphat 2-DE method described here is simple but powerful, and the resulting information will be a useful tool for further proteomic research.

The effects of agarose gel strips without and with 0.03 m(r) electroendosmosis (EEO) on isoelectric focusing (IEF) were studied. It is shown that only agarose without EEO can be used for IEF. The effects of electrode buffer strips using agarose with different EEO of 0, 0.03, 0.08, 0.20 m(r) on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and native PAGE were also studied. It apparently did not affect SDS-PAGE, but affected native PAGE to a certain extent. The higher the EEO value was, the more water was present on the agarose gel strip during a separation. Agarose gel strips with an EEO of 0.2 m(r) are not suitable as electrode buffer strips for native PAGE.

Polyacrylamide gel electrophoresis is a widely used method to study short DNA fragments in solution. It is, however, a relative method requiring length markers to assess mobility, shape, flexibility, and molecularity of the DNA structures of interest. In recent literature we have encountered the use of oligo(dT) fragments as the native PAGE length markers. We show here that this practice is inadequate because oligo(dT) migration is strongly retarded in native polyacrylamide gels. This conclusion is qualitatively true irrespective of the conditions of electrophoresis, oligo(dT) length, and gel concentration. Depending on their length, oligo(dT) fragments migrate 2--4 times slower than that would correspond to their nucleotide number. This leads to erroneous conclusions, e.g., determination of the number of associated molecules in guanine quadruplexes or other DNA complexes.

A new property of a heat-inducible heat shock protein (Hsp) 70.1 that it forms a complex with acidic lipids was first demonstrated. Based on the behaviors of the complexes on the native PAGE, the acidic lipid/Hsp70.1 complexes are categorized into two groups. The first group is the sulfatide-induced large-sized complex, which stays on the gel top on the native PAGE. Only the N-terminal ATPase domain is responsible for the complex formation. The second group is the ganglioside-induced complex, which is diffused in the resolution gel on the native PAGE. Both the N-terminal ATPase and the C-terminal peptide-binding domains are involved in the complex formation. No complex is formed by neutral glyco- and phospholipids. The complex formation with the acidic glyco- and phospholipids implicates the various functions of Hsp70 on the membrane surfaces.

Proline caused irreversible inhibition (involving reduction in V(max) without altering K(m) for RuBP) in Rubisco activity. Proline-induced suppression in Rubisco activity did not exceed beyond approximately 65% of the original activity even upon exposure to higher levels of proline for prolonged duration. However, NaCl-induced reduction in Rubisco activity was reversible. Native PAGE analysis of Rubisco-incubated with proline showed the presence of two distinct bands corresponding to approximately 430 and approximately 28 kDa, but that incubated with NaCl showed a single band. SDS-PAGE analysis revealed that the approximately 430- and approximately 28-kDa bands represent octamers of large subunits and dimers of small subunits, respectively. These results demonstrated for the first time that proline suppresses Rubisco activity by bringing about dissociation of the small subunits from the octamer core of large subunits, probably by weakening hydrophobic interactions between them.