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Heterologous production of proteins in Escherichia coli has raised several challenges including soluble production of target proteins, high levels of expression and purification. Fusion tags can serve as the important tools to overcome these challenges. SUMO (small ubiquitin-related modifier) is one of these tags whose fusion to native protein sequence can enhance its solubility and stability. In current research, a simple, efficient and cost-effective method is being discussed for the construction of pET28a-SUMO vector. In order to improve the stability and activity of lysophospholipase from Pyrococcus abyssi (Pa-LPL), a 6xHis-SUMO tag was fused to N-terminal of Pa-LPL by using pET28a-SUMO vector. Recombinant SUMO-fused enzyme (6 H-S-PaLPL) works optimally at 35 °C and pH 6.5 with remarkable thermostability at 35–95 °C. Thermo-inactivation kinetics of 6 H-S-PaLPL were also studied at 35–95 °C with first order rate constant (kIN) of 5.58 × 10− 2 h-1 and half-life of 12 ± 0 h at 95 °C. Km and Vmax for the hydrolysis of 4-nitrophenyl butyrate were calculated to be 2 ± 0.015 mM and 3882 ± 22.368 U/mg, respectively. 2.4-fold increase in Vmax of Pa-LPL was observed after fusion of 6xHis-SUMO tag to its N-terminal. It is the first report on the utilization of SUMO fusion tag to enhance the overall stability and activity of Pa-LPL. Fusion of 6xHis-SUMO tag not only aided in the purification process but also played a crucial role in increasing the thermostability and activity of the enzyme. SUMO-fused enzyme, thus generated, can serve as an important candidate for degumming of vegetable oils at industrial scale. [ABSTRACT FROM AUTHOR]

Recently, CO2 hydrogenation had a new breakthrough resulting from the design of catalysts to effectively activate linear CO2 with symmetry‐breaking sites. However, understanding the relationship between symmetry‐breaking sites and catalytic activity at the atomic level is still a great challenge. In this study, a set of gold‐copper alloy Au13Cux (x=0–4) nanoclusters were used as research objects to show the symmetry‐controlled breaking structure on the surface of nanoclusters with the help of manipulability of the Cu atoms. Among them, Au13Cu3 nanocluster displays the highest degree of symmetry‐breaking on its crystal structure compared with the other nanoclusters in the family. Where the three copper atoms occupying the surface of the icosahedral kernel unevenly with one copper atom is coordinately unsaturated (CuS2 motif relative to CuS3 motif). As expected, Au13Cu3 has an excellent hydrogenation activity of CO2, in which the current density is as high as 70 mA cm−2 (−0.97 V) and the maximum FECO reaches 99 % at −0.58 V. Through the combination of crystal structures and theoretical calculations, the excellent catalytic activity of Au13Cu3 is revealed to be indeed closely related to its asymmetric structure. [ABSTRACT FROM AUTHOR]

Enzyme immobilization is an attractive strategy to improve enzyme stability, however, the activity significantly reduces after immobilization. To solve this issue, we designed a novel magnetic carrier that both enhanced enzyme activity and improved its stability. For this purpose, the magnetic nanoparticles were synthesized and l-asparaginase was immobilized physically. All materials were structurally and morphologically characterized. Besides, the biochemical properties of the immobilized enzyme were investigated and compared with the free one. Moreover, the activity of the immobilized enzyme was investigated under a weak magnetic field. The optimum pH and optimum temperature of the free and immobilized enzyme were found to be 8.5 and 45 °C, 7.5 and 40 °C, respectively. Moreover, even after 10 cycles of use, the immobilized enzyme retained 54% of its initial activity. Km for free and the immobilized enzyme was found to be 10.37 ± 0.5, and 7.06 ± 2.99 mM, respectively, and Vmax was found to be 138.88 ± 2.64, and 121.95 ± 1.07 µmol/min, respectively. Most importantly, the activity increased approximately 3.2-fold and 4.3-fold at 10 Hz and 20 mT, respectively. Overall, the results suggested that, if the activity of the immobilized enzyme is very low, applying a weak magnetic field may be necessary to enhance the enzyme reaction. [ABSTRACT FROM AUTHOR]

Cuscuta campestris Yunck. is a parasitic weed responsible for severe yield losses in crops worldwide. The selective control of this weed is scarce due to the difficult application of methods that kill the parasite without negatively affecting the infected crop. trans-Cinnamic acid is secreted by plant roots naturally into the rhizosphere, playing allelopathic roles in plant–plant communities, although its activity in C. campestris has never been investigated. In the search for natural molecules with phytotoxic activity against parasitic weeds, this work hypothesized that trans-cinnamic acid could be active in inhibiting C. campestris growth and that a study of a series of analogs could reveal key structural features for its growth inhibition activity. In the present structure–activity relationship (SAR) study, we determined in vitro the inhibitory activity of trans-cinnamic acid and 24 analogs. The results showed that trans-cinnamic acid's growth inhibition of C. campestris seedlings is enhanced in eight of its derivatives, namely hydrocinnamic acid, 3-phenylpropionaldehyde, trans-cinnamaldehyde, trans-4-(trifluoromethyl)cinnamic acid, trans-3-chlorocinnamic acid, trans-4-chlorocinnamic acid, trans-4-bromocinnamic acid, and methyl trans-cinnamate. Among the derivatives studied, the methyl ester derivative of trans-cinnamic acid was the most active compound. The findings of this SAR study provide knowledge for the design of herbicidal treatments with enhanced activity against parasitic weeds. [ABSTRACT FROM AUTHOR]

The processive cellulase (CelO) is an important modular enzyme of Clostridium thermocellum. To study the effect of the carbohydrate‐binding module (CBM3b) on the catalytic domain of CelO (GH5), four engineered derivatives of CelO were designed by truncation and terminal fusion of CBM3b. These are CBM at the N‐terminus, native form (CelO‐BC, 62 kDa); catalytic domain only (CelO‐C, 42 kDa); CBM at the C‐terminus (CelO‐CB, 54 kDa) and CBM attached at both termini (CelO‐BCB, 73 kDa). All constructs were cloned into pET22b (+) and expressed in Escherichia coli BL21 (DE3) star. The expression levels of CelO‐C, CelO‐CB, CelO‐BC, and CelO‐BCB were 35%, 35%, 30%, and 20%, respectively. The enzyme activities of CelO‐C, CelO‐CB, CelO‐BC, and CelO‐BCB against 1% regenerated amorphous cellulose (RAC) were 860, 758, 985, and 1208 units per μmole of the enzyme, respectively. The enzymes were partially purified from the lysate of E. coli cells by heat treatment followed by anion exchange FPLC purification. Against RAC, CelO‐C, CelO‐CB, CelO‐BC, and CelO‐BCB showed KM values of 32, 33, 45, and 43 mg⋅mL–1 and Vmax values of 3571, 3846, 3571, and 4545 U⋅min–1, respectively. CBM3b at the N‐terminus of GH5 linked through a P/T‐rich linker was found to enhance the catalytic activity and thermostability of the enzyme. [ABSTRACT FROM AUTHOR]

[Display omitted] • Bridging the gap between homogeneous and heterogeneous asymmetric organocatalysis. • Effective strategy for solving bottlenecks in heterogeneous asymmetric organocatalysis. • One-pot covalent immobilization of TRIP to PS brush grafted on SiO 2 nanoparticles. • Fast mass transfer due to the open stretching structure of anchored TRIP in toluene. • Sparse grafting density of PS brush in favor of the fast mass transfer of reactants. Reduced mass transfer and tedious immobilization of expensive chiral organocatalyst are two bottlenecks for the large-scale synthesis of optically active molecules in heterogeneous asymmetric organocatalysis. Here, a quasi-homogeneous organocatalysis is achieved by anchoring BINOL-derived phosphoric acid (TRIP) to polystyrene (PS) brush grafted on SiO 2 nanoparticles via one-pot, effectively improving mass transfer due to the open stretching of TRIP-anchored PS brush in toluene. The PS brush enables TRIP to catalyze asymmetric allylation in significantly higher yields and enantioselectivities than PS-supported TRIP, and in slightly higher yields than homogeneous TRIP. The sparser grafting density of PS brush is more conducive to the swelling of PS brush, leading to the faster mass transfer of reactants from the top to end of PS brush. Overall, the one-pot anchoring of TRIP to PS brush combines the advantages of homogeneous and heterogeneous organocatalysis, providing an ideal strategy for solving the two bottlenecks in heterogeneous asymmetric organocatalysis. [ABSTRACT FROM AUTHOR]

Cuscuta campestris Yunck. is a parasitic weed responsible for severe yield losses in crops worldwide. The selective control of this weed is scarce due to the difficult application of methods that kill the parasite without negatively affecting the infected crop. trans-Cinnamic acid is secreted by plant roots naturally into the rhizosphere, playing allelopathic roles in plant–plant communities, although its activity in C. campestris has never been investigated. In the search for natural molecules with phytotoxic activity against parasitic weeds, this work hypothesized that trans-cinnamic acid could be active in inhibiting C. campestris growth and that a study of a series of analogs could reveal key structural features for its growth inhibition activity. In the present structure–activity relationship (SAR) study, we determined in vitro the inhibitory activity of trans-cinnamic acid and 24 analogs. The results showed that trans-cinnamic acid’s growth inhibition of C. campestris seedlings is enhanced in eight of its derivatives, namely hydrocinnamic acid, 3-phenylpropionaldehyde, trans-cinnamaldehyde, trans-4-(trifluoromethyl)cinnamic acid, trans-3-chlorocinnamic acid, trans-4-chlorocinnamic acid, trans-4-bromocinnamic acid, and methyl trans-cinnamate. Among the derivatives studied, the methyl ester derivative of trans-cinnamic acid was the most active compound. The findings of this SAR study provide knowledge for the design of herbicidal treatments with enhanced activity against parasitic weeds.

In recent years, studies on the external stimulation of biotechnological enzyme drugs and their use in the treatment of diseases have gradually increased. Herein, for the first time, the near-infrared (NIR) was used as an external stimulant to manipulate the catalytic activity of the uricase (UOx) enzyme, which is used in the treatment of hyperuricemia, in a controlled manner. For this purpose, NaYF 4 : Yb3+, Er3+ upconverting nanoparticles (UCNPs) were synthesized by hydrothermal synthesis method and functionalized with diethylaminoethyldextran (DEAE-D) to facilitate UOx immobilization. The obtained materials were characterized in detail by various methods to confirm the preparation of UCNPs and immobilization of UOx. In addition, the biochemical parameters such as optimum pH, optimum temperature, thermal stability, and reusability were preliminarily investigated for free UOx and NaYF 4 : Yb3+, Er3+/DEAE-D/UOx. Moreover, a sequential experimental method was monitored to assess the effects of NIR excitation intensity, induction distance, and exposure time on the UOx activity. While the optimum pH value was found to be 6.0 for both enzyme forms, the optimum temperature value was recorded as 45 and 50 °C for free UOx and NaYF 4 : Yb3+, Er3+/DEAE-D/UOx, respectively. The activation energy (E a) values of free UOx and NaYF 4 : Yb3+, Er3+/DEAE-D/UOx were calculated to be 7.59 and 2.98 kJ/mol, respectively, implying that the NaYF 4 : Yb3+, Er3+/DEAE-D/UOx was less temperature sensitive. After thermal incubation for 3 h at 55 °C, the NaYF 4 : Yb3+, Er3+/DEAE-D/UOx retained 54.68 % of its initial activity, while the free UOx retained 32.94 % of its initial activity at 50 °C. In addition, the findings from the reusability experiments revealed that NaYF 4 :Yb3+, Er3+/DEAE-D/UOx retained 57.94 % of its initial activity even after 10 reuse cycles. The most striking point in this study was the positive manipulation of UOx activity by NIR. Accordingly, it was observed that when the NIR power was 1500 mW, the UOx activity increased about 2 times compared to the control. Additionally, the UOx activity increased in parallel with the increase in NIR application time and the ideal application distance was 3 cm. In conclusion, this pioneering study provides valuable insights into the controlled manipulation of enzyme activity, showcasing the effectiveness of NIR in enhancing enzyme activity. The outcomes suggest that NIR holds great promise as an efficient, sustainable, and versatile approach applicable to various enzymatic catalysis scenarios. • A novel support (NaYF 4 : Yb3+, Er3+/DEAE-D) was synthesized for UOx immobilization. • Physicochemical and biochemical characterizations were carried out. • NaYF 4 : Yb3+, Er3+/DEAE-D/UOx had hydrodynamic diameter of 415.08 nm and zeta potential of 0.99 mV. • NaYF 4 : Yb3+, Er3+/DEAE-D/UOx showed relative activity of 57.94 % after 10 cycles. • More than 2-fold activity was achieved with immobilized UOx under NIR irradiation. [ABSTRACT FROM AUTHOR]

Nanoporous materials with core-shell structure have received lots of attention owing to the great versatility of the functional cores and shells and their potential application in catalysis and biological applications. In this work, a facile method has been developed to synthesize uniform Au@Pt@mesoporous SiO2 nanostructures with high peroxidase-like activity, which had a well-defined core–shell structure with Au nanorods@Pt nanodots as a core and mesoporous SiO2 as a shell. The mesoporous SiO2 shell can not only provide convenient transmission channels but offer a substantial location for accommodation of large biomolecules, such as antibodies and antigens. Here a novel nanoprobe based on Au@Pt@mesoporous SiO2 nanozyme modified with mumps antigens was reported. Notably, the encapsulation of Au@Pt nanorod in mesoporous SiO2 shell was able to hinder the interaction between catalytical nanoparticles and recognition antigens, retaining the catalytic activity of the inner active nanoparticle core. Furthermore, this nanoprobe exhibited an extraordinarily stability and showed excellent activity. As a result, we presented an enzyme linked immunosorbant assay (ELISA) for the diagnosis of mumps virus; this proposed method exhibited good sensitivity to mumps-specific IgM antibodies. The limit of detection can be as low as 10 ng/mL, which was more sensitive compared to the conventional immunoassay. Our results indicated that this nanoprobe hold great promise with opportunities for applications of biosensors, catalysis and biotechnology.

Development of novel and robust oxygen evolution reaction (OER) catalysts with well-modulated atomic and electronic structure remains a challenge. Compared to the well-known metal hydroxides or (oxyhydr)oxides with lamellar structure, delafossites (ABO2) are characterized by alternating layers of A cations and edge-sharing BO2 octahedra, but are rarely used in OER due to their poor electron conductivity and intrinsic activity. Here, we propose a delafossite analog by mutation of metal oxyhydroxide and delafossite based on first-principles calculations. Modulation on the electronic structure due to distortion of the original crystal field of the BO2 layers is calculated to enhance electron conductivity and catalytic activity. Inspired by the theoretical design, we have experimentally realized the delafossite analog by electrochemical selfreconstruction (ECSR). Operando X-ray absorption spectroscopy and other experimental techniques reveal the formation of delafossite analog with Ag intercalated into bimetallic cobalt-iron (oxyhydr) oxide layers from a metastable precursor through amorphization. Benefitting from the featured local electronic and geometric structures, the delafossite analog shows superior OER activity, affording a current density of 10 mA·cm-2 at an overpotential of 187 mV and an excellent stability (300 h) in alkaline conditions. [ABSTRACT FROM AUTHOR]

The global challenge to the treatment of malaria is mainly the occurrence of resistance of malaria parasites to conventionally used antimalarials. Artesunate, a semisynthetic artemisinin compound, and other artemisinin derivatives are currently used in combination with selected active antimalarial drugs in order to prevent or delay the emergence of resistance to artemisinin derivatives. Several methods, such as preparation of hybrid compounds, combination therapy, chemical modification and the use of synthetic materials to enhance solubility and delivery of artesunate, have been employed over the years to improve the antimalarial activity of artesunate. Each of these methods has advantages it bestows on the efficacy of artesunate. This review discussed the various methods employed in enhancing the antimalarial activity of artesunate and delaying the emergence of resistance of parasite to it. [ABSTRACT FROM AUTHOR]

The lipase was successfully immobilization in the presence of proline into metal organic frameworks (MOFs, ZIF-8) by self-assembling biomineralization method which showed superior catalytic properties. • Lipase was activated in the presence of proline and successfully immobilized within ZIF-8. • The prepared hybrid biocatalyst was characterized by FT-IR, FT Raman, XRD, SEM and TGA techniques. • The thermal kinetics study showed 4-fold improved thermal stability than native enzyme. • The lipase-proline MOF showed 72% residual activity after recycling for six cycles. The immobilization of enzyme with enhanced catalytic activity is the major challenge. In this work, we have activated the lipase in the presence of proline and successfully immobilized into zeolitic imidazolate framework (ZIF)-8 by biomineralization method. The prepared lipase–proline MOF exhibited 135% enhanced catalytic activity as compared to free counterpart. Further, it exhibited four-fold improved thermal stability with respect to native enzyme after immobilization. In Michaelis–Menten kinetic studies, K m values for lipase–proline MOF were found to be lower, whereas, it exhibited higher V max than lipase–MOF and free lipase. The lipase–MOF and lipase–proline MOF were showed 56% and 72% residual activity, respectively after six cycles of reuse. [ABSTRACT FROM AUTHOR]

Mostly, enzyme activity is reduced after immobilization of enzyme within MOF due to unfavourable conformational changes occurred during the immobilization procedure. In this context, lipase was activated by surfactants (in order to get a highly active enzyme) followed by encapsulation within zeolitic imidazolate framework (ZIF)-8 via one-pot facile self-assembly method. The prepared lipase-SDS ZIF-8 exhibited 250% enhanced activity compared to native form. The prepared biocomposite was characterized and analysed by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and scanning electron microscopy (SEM). Thermo-stability was determined for prepared lipase-SDS ZIF-8 biocomposite in the range of 50–70 °C, which showed more than two-folds enhanced stability in terms of half-life. Further, immobilized lipase retained 76% of residual activity even after six repetitive cycles and, it showed 91% residual activity after twenty days of long term storage. Finally, lipase-SDS ZIF-8 was tested for chemical stability in polar denaturing solvents which showed excellent stability as compared to free lipase. An enhanced surfactant activated lipase-SDS MOF prepared by self-assembly biomineralization method which exhibited excellent catalytic activity and recyclability. Unlabelled Image • Surfactant modified lipase was entrapped within MOF with higher retention in activity. • The prepared Lipase-SDS MOF was analysed and characterized by using FT-IR, XRD and SEM. • Improved thermal stability of Lipase-SDS MOF was expressed as half-life and deactivation energy. • Lipase-SDS MOF exhibited enhanced reusability and storage stability for industrial application. • Improved tolerance towards polar denaturing solvents was exhibited by lipase-SDS MOF. [ABSTRACT FROM AUTHOR]

Enhanced cellulase production was studied with ultraviolet mutagenesis and the mutated cellulase gene in E. coli DH5α was cloned for production under controlled conditions. Aspergillus niger inoculum was exposed to UV radiation for different time intervals. The UV exposure of 10 min to A. niger yielded 330 μmol/min/mg specific activity. The mRNA of mutant A. niger yielding maximum enzyme activity was isolated and used for the synthesis of cDNA. The cDNA prepared from mRNA was used for the PCR amplification of mutated cellulase gene with primers designed on the basis of a cellulase gene database from A. niger. The amplified cellulase gene was cloned into E. coli DH5α followed by expression in E. coli BL21. The cellulase activity by wild type A. niger, A. niger UVMT-I, and recombinant E. coli was compared by analysis of variance test. The specific activity of cellulase by recombinant E. coli was maximum (441 μmol/min/mg), followed by A. niger UVMT-I (330 μmol/min/mg) and wild type A. niger (96 μmol/min/mg). [ABSTRACT FROM AUTHOR]

Abstract: Here, we built Ru‐decorated Pt/C nanoparticles with different coverage degrees (θRu) by wall‐jet configuration for the first time, and we investigated their catalytic properties towards glycerol electrooxidation in acidic medium. Moreover, we used the most active catalysts as the anode in electrolysis to produce carbonyl compounds. The use of an electrochemical cell in wall‐jet configuration allows for the controlling of electrodeposition through easily handling parameters; namely, the θRu is controlled by changing the concentration of the metallic precursor, speed, and volume of injection onto a Pt/C‐modified glassy carbon electrode under applied potential. Excess of Ru on a Pt surface inhibits glycerol dissociative adsorption, which limits further electrooxidation; whereas low θRu do not provide surface oxygen species to the anodic reaction. Hence, intermediates θRu reveal active catalysts – namely, θRu=0.42 shifts the onset potential 170 mV towards lower values and increases 1.65‐fold the current density at 0.5 V. The stability of this catalyst is also enhanced by maintaining a more constant current density during successive potential cycles in the presence of glycerol and by avoiding Ru leaching from the surface. The electrolysis on Ru‐decorated Pt/C is shown to lead the reaction towards formic acid (‘high oxidation state’), decreasing the amounts of glyceradehyde, glycolic acid, and dihydroxyacetone, as a result of the improved catalytic properties. [ABSTRACT FROM AUTHOR]

A facile and robust strategy to fabricate organocatalyst-functionalized hollow double-shelled nano-bowl was developed for the first time by hard-templating synthesis. After the core was etched by DMF, the outer shell thicknesses below 50 nm and above 50 nm deformed into hollow nano-bowl and hollow nanosphere, respectively. Furthermore, the outer shell with the average thickness of 20–50 nm deformed into hollow double-shelled nano-bowl with a void between two semi-shells. However, the shell with the thicknesses below 20 nm severely deformed into hollow nano-bowl with no void owing to the overlapping of two semi-shells. Compared with hollow nanosphere and nano-bowl with no void, hollow double-shelled nano-bowl displayed superior catalytic performances owing to the thin shell thickness and a void between two semi-shells. In heterogeneous asymmetric Michael addition, the double-shelled nano-bowl exhibited good to excellent yields (86–98%), stereoselectivities ( syn/anti  = 81–93/19–7 and 93–99%ee syn ) and good reusability. [ABSTRACT FROM AUTHOR]

The modification of the surface of Ag nanoparticles supported on carbon black (Ag/C) with a small amount of Pd and the electrooxidation of allyl alcohol on the Pd-modified Ag/C (Pd/Ag/C) catalysts are investigated. The Pd/Ag/C catalysts with Pd/Ag atomic ratios of 0.45–1.48:100 are prepared by electrochemically depositing Pd on Ag/C. Structural characterization by scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, inductively coupled plasma mass spectrometry, X-ray photoelectron spectroscopy, and electrochemical analysis reveal low loadings and small surface areas of the deposited Pd. The Pd/Ag/C catalysts are superior to Pd/C in activity for the electrooxidation of allyl alcohol in alkaline solution. When evaluated in terms of the glassy carbon substrate, Pd/Ag/C shows more negative onset and peak potentials and higher peak intensities than Pd/C, although Pd/C has a relatively high activity and the Pd loadings of Pd/Ag/C are much lower than that of Pd/C. When evaluated in terms of the electrochemically active surface area of Pd or the Pd loading mass, Pd/Ag/C has great advantages over Pd/C in activity. For instance, the Pd-mass activity of Pd/Ag/C is up to nearly 200 times that of Pd/C. Low cost is another striking advantage of the Pd/Ag/C catalysts. For ethanol oxidation, on the other hand, the Pd/Ag/C catalysts have no activity, while Pd/C has a relatively high activity. [ABSTRACT FROM AUTHOR]

The enzyme under lower-intensity ultrasonic irradiation leads to favorable conformational changes, thereby enhancing its activity. In this study, lipase activity was augmented upto 1.6-folds after ultrasonic treatment at 22 kHz and 11.38 W cm −2 for 25 min. This highly activated lipase was encapsulated within zeolite imidazolate framework-8 (ZIF-8) as a metal-organic framework (MOF) material via facile one-step biomineralization method by simply mixing aqueous solution of 2-methylimidazole (13.3 mmol) and zinc acetate (1.33 mmol) along with sonicated lipase within 10 min at room temperature (28 ± 2 °C). The prepared lipase-MOF was characterized by using FT-IR, FT-Raman, XRD, BET, confocal scanning laser microscopy, TGA and SEM. Further, the thermal stability of lipase embedded MOF was evaluated in the range of 55–75 °C on the basis of half-life which showed 3.2 folds increment as against free lipase. In Michaelis–Menten kinetics studies, sonicated lipase entrapped MOF showed nearly same K m and V max values as that of sonicated free lipase. Moreover, the immobilized lipase exhibited up to 54% of residual activity after seven successive cycles of reuse, whereas it retained 90% of residual activity till twenty-five days of storage. Finally, the conformational changes occurred in lipase after sonication treatment and encapsulation within MOF were analyzed by using FT-IR data analysis tools and fluorescent spectroscopy. [ABSTRACT FROM AUTHOR]

Ciprofloxacin is a broad spectrum bactericidal anti-infective agent of the fluoroquinolones class used in treatment of many bacterial infections. In recent times, there has been increasing resistance to the antibiotic. In this work, we investigated the effect of making an ion- pair complex of Ciprofloxacin – hydrochloride with Sodium cholate on bacterial activity. The optimal ratio of the reactants and pH were determined using UV spectrometry. The complex was characterized by octanol-water partitioning, melting point, and IR spectrometry. The antibacterial activity of the complex was determined against Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, and Streptococcu s pneumoniae by the agar-well diffusion method. The complex was whitish to off-white in color and crystalline, with a melting point of 238 °C. The stoichiometry of the complex shows a molar ratio of 1:1 of sodium cholate to ciprofloxacin. The best pH for complexation was pH 9. The complex partitioned 3.38 times into octanol than in water. The FTIR revealed interaction between the 4-nitrogen atom in the 7-piperazinyl group of ciprofloxacin and the carbonyl of the cholate. The drug in complex form gave double the antibacterial activity of the uncomplexed drug. This study showed that development of hydrophobic ion pair complex enhances antibacterial activity of ciprofloxacin hydrochloride. [ABSTRACT FROM AUTHOR]

In this paper, ultrathin Pt nanowires (Pt NWs) and PtNi alloy nanowires (PtNi NWs) supported on carbon were synthesized as electrocatalysts for oxygen reduction reaction (ORR). Pt and PtNi NWs catalysts composed of interconnected nanoparticles were prepared by using a soft template method with CTAB as the surface active agent. The physical characterization and electrocatalytic performance of Pt NWs and PtNi NWs catalysts for ORR were investigated and the results were compared with the commercial Pt/C catalyst. The atomic ratio of Pt and Ni in PtNi alloy was approximately 3 to 1. The results show that after alloying with Ni, the binding energy of Pt shifts to higher values, indicating the change of its electronic structure, and that PtNi NWs catalyst has a significantly higher electrocatalytic activity and good stability for ORR as compared to Pt NWs and even Pt/C catalyst. The enhanced electrocatalytic activity of PtNi NWs catalyst is mainly resulted from the downshifted-band center of Pt caused by the interaction between Pt and Ni in the alloy, which facilitates the desorption of oxygen containing species (O or OH) and the release of active sites. [ABSTRACT FROM AUTHOR]

Alloying platinum with a second metal such as palladium can increase the mass activity of Pt and lower the usage of expensive Pt elements, hence is of great importance for designing highly efficient and cost-effective electrocatalysts for oxygen reduction reaction (ORR). In this study, monomorphic PtPd alloyed worm-like nanoparticles (PtPd WNPs) with dominant (111) facets were prepared with a facile one-pot approach. The detailed morphology, composition, and surface structure of the PtPd WNPs were investigated by transmission electron microscopy (TEM), scanning electron microscopy (SEM), selected-area electron diffraction (SAED), energy dispersive spectrum (EDS), X-ray diffraction (XRD), as well as X-ray photoelectron spectroscopy (XPS). The prepared PtPd WNPs displayed enhanced electrocatalytic activity and remarkably robust stability toward ORR in both alkaline and acidic media, superior than commercial Pt/C catalysts. This strategy may open a new route to design and prepare advanced electrocatalysts for fuel cells. [ABSTRACT FROM AUTHOR]

A three-dimensional (3D) assembly of PtNi alloy nanosticks (NSA) is synthesized through an effective organic solvothermal approach to enhance the specific activity and long-term durability for the oxygen reduction reaction (ORR). The 3D PtNi NSA is composed of interconnected nanosticks with an average diameter of approximately 5 nm, which are confirmed to be of high crystallinity with ordered atomic arrangement of ORR-favorable PtNi (111). After an electrochemical dealloying process, the surface of the nanosticks becomes rough with a large quantity of step-like nanostructures, which are verified to effectively improve the ORR activity. The electrochemical results of half-cell tests demonstrate that the 3D PtNi alloy NSA exhibits a 4.5 times higher mass activity than the Pt/C (20 wt%, JM) catalyst (0.58 A/mg) and a 5.1 times higher specific activity (742 μA/cm2). Most importantly, after the accelerated deterioration test, the 3D PtNi alloy NSA catalyst shows almost no activity decrease, both in half- and single-cell tests. The 3D PtNi alloy NSA prepared here is indeed a promising electrocatalyst for practical electrocatalytic applications. [ABSTRACT FROM AUTHOR]

An organic–inorganic hybrid glucoamylase nanoflower was prepared in single pot by simple, facile and highly efficient method. The stepwise formation of enzyme-embedded hybrid nanoflowers and influence of experimental parameters viz. pH of solution mixture, enzyme and copper ion concentration on the activity of prepared hybrid nanoflowers were systematically investigated. The self-assembled hybrid glucoamylase nanoflowers were synthesized by mixing aqueous solution of copper sulphate (200 mM) with PBS (pH 7.5, 5 mM) containing glucoamylase (1 mg/mL) in 24 h at room temperature. These prepared nanoflowers were further characterized by FT-IR, SEM and XRD. The hybrid nanoflowers exhibited 204% enhanced activity recovery and two folds improvement in thermal stability in terms of half-life (in the range of 50–70 °C) with respect to the free form. The hybrid glucoamylase nanoflowers retained 70% residual activity after eight successive cycles indicating their excellent durability. Additionally, the nanoflowers retained up to 91% residual activity upto 25 days of storage. Moreover, the conformational changes occurred in glucoamylase structure after preparing hybrid nanoflowers were evaluated by FT-IR spectroscopy data tools. [ABSTRACT FROM AUTHOR]

BACKGROUND The development of effective and green peroxymonosulfate ( PMS) activation processes has attracted considerable attention and still remains a great challenge in the environmental field. Herein, the cobalt catalyst was innovatively supported onto activated carbon fibers ( ACFs) to construct an outstanding heterogeneous catalyst, Co@ ACFs, for PMS activation. RESULTS Co@ ACFs could effectively activate PMS to decompose dyes with about 100% removal rate in 35 min. Co@ ACFs maintained its catalytic ability without detectable Co leaching during repeated batch experiments. More importantly, the catalyst presented an enhanced decomposition performance over most reported heterogeneous Co catalysts due to the significant role of ACFs: (i) high adsorption capacity in favor of the enhanced catalytic activity; (ii) ACFs as an electron donor to accelerate CoII/ CoIII cycle thereby speeding up degradation. Combining electron paramagnetic resonance ( EPR) with radical scavengers, it was found that both sulfate and hydroxyl radicals ( SO4•-, • OH) were responsible for the degradation of dyes. Unexpectedly, • OH was the dominant radical, different from the reported mechanism in typical Co/ PMS. CONCLUSION This study not only paves the way to further develop highly efficient and green PMS activation processes, but also provides a new practical method for application to wastewater remediation. © 2015 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Rational design of Z-scheme heterojunction is known to be a good strategy for promoting photogenerated charge efficient separation. In this paper, a direct Z-scheme Ag 2 O/Bi 2 MoO 6 heterostructured microspheres with good interfacial properties were successfully prepared by hydrothermal synthesis-coprecipitation-calcination decomposition. Various techniques such as Transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), and powder X-ray diffraction (PXRD) were used to reveal the structure, morphology, composition, electrochemical and optical properties of the target product. The catalytic activity of the as-prepared composite was evaluated by visible light degradation of Rhodamine B (RhB) and transient photocurrent. As expected, the results showed that 1:5 Ag 2 O/Bi 2 MoO 6 exhibited the optimal catalytic performance. And the visible degradation efficiency is up to 86% in 90 min, which was 2.69 times higher than that of Bi 2 MoO 6 (32%). And 1:5 Ag 2 O/Bi 2 MoO 6 exhibited the highest photocurrent efficiency (0.8 μA/cm2). Meanwhile, the efficiency of 1:5Ag 2 O/Bi 2 MoO 6 keep 90% after four cycles. The enhanced activity can be attributed to the formation of a good interfacial contact between Ag 2 O and Bi 2 MoO 6. In addition, hole and superoxide were identified as the main active species. Eventually a possible direct Z-scheme mechanism was proposed to explain enhanced performance. This work may provide a new perspective for the rational design of excellent Bi 2 MoO 6 -based Z-scheme heterojunctions for environmental remediation. [Display omitted] • Ag 2 O/Bi 2 MoO 6 heterostructured microspheres were successfully prepared. • This heterostructure with good interfacial contact can effectively promote charge separation. • Ag 2 O/Bi 2 MoO 6 microspheres show good activity and exceptional stability. • Enhanced activity can be explained by direct Z scheme heterojunction. [ABSTRACT FROM AUTHOR]

The present work reports the use of biocatalyst and ultrasound for greener synthesis of cinnamyl propionate. The lipase Pseudomonas cepacia was immobilized on a copolymer of hydroxypropyl methyl cellulose and polyvinyl alcohol. This biocatalyst was u sed for ultrasound-assisted synthesis of cinnamyl propionate with the detailed optimization of various reaction parameters. Besides this, protocol was extended to synthesize various industrially important propionate esters. In addition to this, different enzyme-kinetic parameters such as r and K K and K were studied which presented ordered bi-bi mechanism with an inhibition by cinnamyl alcohol. The developed biocatalyst demonstrated enhancement in catalytic activity and recyclability up to five recycles. Moreover, the biocatalyst was tested to investigate the effects of sonication via various characterization techniques such as scanning electron microscopy, thermogravimetry, and water content analysis. [ABSTRACT FROM AUTHOR]

Trypsin (Trp) is arguably the most important member of the serine proteases. Constructs made up of gold nanoparticles (GNP) with trypsin have been known to exhibit increased efficiency and stability in various experiments. Here we report simple Trp–GNP constructs mixed in different trypsin-to-GNP ratios which exhibit higher efficiencies in biochemical assay, varying resistance to autolysis and higher ability in cell trypsinization. Trp–GNP constructs in different trypsin-to-GNP ratios exhibit prolonged and sustained activity compared to native trypsin in N-α-p-benzoyl-p-nitroanilide (BAPNA) assay as monitored by UV-Visible spectroscopy. The activity was monitored as a function of decreasing rate of linear release of p-nitro aniline (resulting from the cleavage of BAPNA by trypsin) with time during the assay, whose absorbance was measured at 410 nm ( λ max p-nitro aniline). We have done extensive studies to understand structural basis of this trypsin GNP interaction by using atomic force microscopy (AFM), transmission electron microscopy (TEM) and circular dichroism (CD) techniques. Our findings suggest that on interaction, the gold nanoparticles probably form an adherent layer on trypsin that effectively changes the morphology and dimensions of the nanoconstructs. However, trypsin-to-GNP ratio is extremely important, as higher concentration of GNP might damage the conformation of protein. Stability studies related to denaturation show that 1:1 Trp–GNP constructs exhibit maximum stability and high efficiency in all assays performed. [ABSTRACT FROM AUTHOR]

BACKGROUND A novel heterogeneous Fenton-like catalyst (FePy-CFs) was prepared by supporting 4-aminopyridine iron (FePy) onto cellulose fibers (CFs) by covalent bonds for the rapid decoloration of Rhodamine B (RhB). RESULTS Compared with the use of homogeneous FePy alone, the introduction of CFs to FePy significantly enhanced the catalytic decoloration of RhB. In addition, repetitive tests revealed that FePy-CFs could maintain high catalytic activity in 15 successive runs, suggesting FePy-CFs has excellent sustaining catalytic ability. More importantly, compared with the traditional homogeneous Fenton reagent, the catalytic reaction could proceed over a wider range of pH values from acidic to alkaline. Various scavengers and probe compounds combined with electron paramagnetic resonance (EPR) technology had been used to identify the active species involved in the catalytic system. The results indicated that hydroxyl radicals (•OH), peroxy radicals (•HO2) and high-valent iron (Fe(IV)) may be responsible for the decoloration of RhB. Furthermore, the effects of operational parameters and thermodynamic parameters have also been investigated. CONCLUSION This study not only opens a new perspective for the development of highly efficient catalytic systems, but also extends the potential applications of cellulose fibers in wastewater treatment. © 2014 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Our previous investigation on high pressure supercritical carbon dioxide treatment of a bacterial α-amylase had revealed enhanced activity of the same. 1 H NMR analysis of the activity enhanced enzyme led the authors to hypothesize that the enhancement was possibly owing to alterations in the active site of the enzyme. In the present study, the changes in the active site of the treated enzyme was analysed by Fourier-transform Raman (FT-Raman) spectroscopy. The spectra obtained revealed shifting of bands in the active site of α-amylase indicating a nudging effect of the bonds in this region consequent to high pressure treatment. Also, shifts in bands in the OH stretching vibration of water were observed in the enzyme spectra. These variations in the spectra confirmed changes in the active site as well as in the water associated with the same that perhaps had a concerted effect on the increased activity of α-amylase. [ABSTRACT FROM AUTHOR]

Highlights: [•] Developing a novel heterogeneous Fenton-like catalyst of QuFe@ACFs. [•] Presenting a remarkable pH-tolerant performance at a wide pH range. [•] Exhibiting the excellent sustained catalytic ability and reusable capability. [Copyright &y& Elsevier]

[Display omitted] • Levulinate based deep eutectic solvents (DES) was synthesized and characterized. • The effect of levulinate based DES on galactosidase activity was investigated. • The levulinate based DES, added to the reaction medium, significantly enhanced β-galactosidase activity. • Lactose rates of hydrolysis of Lactose using β-galactosidase were more than threefold enhanced. A series of new deep eutectic solvents based on choline levulinate and various hydrogen bond donors were prepared and characterized by 1H NMR, FT-IR, TG, and DSC. In particular, their physicochemical properties (density, viscosity, conductivity, and thermal stability) were determined and their usability as an enhancing additive to the enzymatic reaction mixture, for the enzyme was checked. It has been shown, that prepared DES, exhibits low viscosity (at 40 °C within the range 0.1–0.8 Pa·s), high thermal stability (in almost all cases above 150 °C), and density within the range 1.1–1.17 g cm−3. Also, it has been shown, that obtained mixtures can stabilize the enzymes, and positively influence on its activity. The addition of up to 15% (v/v) of DES mixture composed of choline levulinate: ethylene glycol, enhanced more than threefold lactose hydrolysis yield by β-galactosidase. The present study shows the relevance of the newly designed DES series for improving enzymes properties with the potential to apply in the effective conversion of food processing origin substrates. [ABSTRACT FROM AUTHOR]

Highlights: [•] The Al2O3–MO showed high thermal stability. [•] The Al2O3–MO catalysts have large amount of surface oxygen species. [•] The Al2O3 pillars could promote the mobility of the active oxygen. [•] The Al2O3–MO catalysts showed excellent DME catalytic combustion activity. [•] The transient response method was used to evaluate the role of the lattice oxygen. [ABSTRACT FROM AUTHOR]

Abstract: Activated carbon fibers supported ferric ion (Fe@ACFs) have been reported as a heterogeneous Fenton catalyst for the efficient removal of dyes, including acid, reactive, and basic dyes. The catalysts presented sustained catalytic ability and in situ regeneration capability in these experiments. Moreover, the Fe@ACFs/H2O2 system also exhibited remarkable catalytic activity across a wider pH range. Importantly, compared with most reported supports, the introduction of ACFs contributed specifically to the activity enhancement of ferric ion. NaCl played a passive role in the degradation of RR M-3BE, consistent with the traditional Fenton reaction. The presence of isopropanol, as a hydroxyl radical (∙OH) scavenger, had a passive influence on RR M-3BE oxidation as well, indicating the hydroxyl radical was involved as the active species, confirmed by Electron Paramagnetic Resonance (EPR). Furthermore, the superoxide radical (HO2∙), which existed in the homogeneous Fenton system, was not detected by EPR in the Fe@ACFs/H2O2 system, suggesting better use of H2O2 for degradation of dyes. This paper discusses a possible catalytic oxidation mechanism in the Fe@ACFs/H2O2 system, which may be a feasible approach for the elimination of widely existing pollutants. [Copyright &y& Elsevier]

High surface area carbon supported Pt and PtSn catalysts were synthesized by microwave irradiation and investigated in the ethanol electro-oxidation reaction. The catalysts were obtained using a modified polyol method in an ethylene glycol solution and were characterized in terms of structure, morphology and composition by employing XRD, STM and EDX techniques. The diffraction peaks of PtSn/C catalyst in XRD patterns are shifted to lower 2θ values with respect to the corresponding peaks at Pt/C catalyst as a consequence of alloy formation between Pt and Sn. Particle size analysis from STM and XRD shows that Pt and PtSn clusters are of a small diameter (∼2 nm) with a narrow size distribution. PtSn/C catalyst is highly active in ethanol oxidation with the onset potential shifted for ∼150 mV to more negative values and with ∼2 times higher currents in comparison to Pt/C. [ABSTRACT FROM AUTHOR]

A luciferase from the railroad worm (Phrixothrix hirtus) is the only red-emitting bioluminescent enzyme in nature that is advantageous in multicolor luciferase assays and in bioluminescence imaging (BLI). However, it is not used widely in scientific or industrial applications because of its low activity and stability. By using site-directed mutagenesis, we produced red-emitting mutants with higher activity and better stability. Compared with the wild-type (WT), the luminescent activities from extracts of cultured mammalian cells expressing mutant luciferase were 9.8-fold in I212L/N351K, 8.4-fold in I212L, and 7.8-fold in I212L/S463R; and the cell-based activities were 3.6-fold in I212L/N351K and 3.4-fold in N351K. The remaining activities after incubation at 37°C for 10 min were 50.0% for I212L/S463R, 31.8% for I212L, and 23.0% for I212L/N351K, but only 5.2% for WT. To demonstrate an application of I212L/N351K, cell-based BLI was performed, and the luminescence signal was 3.6-fold higher than in WT. These results indicate that the mutants might improve the practicability of this signaling in bioassays and BLI. [ABSTRACT FROM AUTHOR]

[Display omitted] • Methanosarcina mazei pyrrolysyl-tRNA synthetase (MmPylRS) activity was enhanced when coupled with Ca. Methanomethylphilus alvus tRNAPyl (CmaPylT). • CmaPylT enhance MmPylRS activity by stabilizing full length MmPylRS. • CmaPylT prevents M mPylRS from cleavage after A189. • Introducing P188 mutations to M mPylRS generally improves activity of MmPylRS variants. • This discovery will be generally useful to develop systems for enhanced incorporation of noncanonical amino acids at amber codon. The amber suppression-based noncanonical amino acid (ncAA) mutagenesis technique has been widely used in both basic and applied research. So far more than two hundred ncAAs have been genetically encoded by amber codon in both prokaryotes and eukaryotes using wild-type and engineered pyrrolysyl-tRNA synthetase (PylRS)-tRNAPyl (PylT) pairs. Methanosarcina mazei PylRS (MmPylRS) is arguably one of two most used PylRS variants. However, it contains an unstable N -terminal domain that is usually cleaved from the full-length protein during expression and therefore leads to a low enzyme activity. We discovered that the cleavage takes place after A189 and this cleavage is inhibited when MmPylRS is co-expressed with Ca. Methanomethylophilus alvus tRNAPyl (CmaPylT). In the presence of CmaPylT, MmPylRS is cleaved after an alternative site K110. MmPylRS is active toward CmaPylT. Its combined use with CmaPylT leads to enhanced incorporation of Nε -Boc-lysine (BocK) at amber codon. To prevent MmPylRS from cleavage after A189 in the presence of its cognate M. mazei tRNAPyl (MmPylT), we introduced mutations at P188. Our results indicated that the P188G mutation stabilizes MmPylRS. We showed that the P188G mutation in wild-type MmPylRS or its engineered variants allows enhanced incorporation of BocK and other noncanonical amino acids including Nε -acetyl-lysine when they are co-expressed with MmPylT. [ABSTRACT FROM AUTHOR]

Abstract: Polyoxometalate anion PMo12O40 3− (POM) is chemically impregnated into a Pt-supported carbon nanotubes (Pt/CNTs) catalyst that is prepared via a colloidal method. The POM-impregnated Pt/CNTs catalyst system (Pt/CNTs-POM) shows at least 50% higher catalytic mass activity with improved stability for the electrooxidation of methanol than Pt/CNTs or POM-impregnated Pt/C (Pt/C-POM) catalyst systems. The enhancement in electrochemical performance of the Pt/CNTs-POM catalyst system can be attributed to the combined beneficial effects of improved electrical conductivity due to the CNTs support, highly dispersed Pt nanoparticles on the CNTs, and increased oxidation power of the polyoxometalate that can assist oxidative removal of reaction intermediates adsorbed on the Pt catalyst surface. [Copyright &y& Elsevier]

Pt loaded Y, USY, beta, mordenite, ZSM-12, and ZSM-5 zeolites with different Si/Al ratios and a USY and ZSM-12 sample having enhanced activity were studied for the hydroisomerization of n-heptane. All the possible heptane isomers were obtained over Pt/H-ZSM-12 and the product distribution was closer to that over Y and beta catalysts, but very different from that over Pt/H-ZSM-5. Shape-selective effects in ZSM-12 resulted in a significantly higher isomer yield than the beta and Y-zeolite catalysts. For Y, beta, and ZSM-12 samples having very little extraframework aluminum, changing the Si/Al ratio did not affect the isomer yield. However, USY and ZSM-12 samples that showed enhanced activity were very sensitive to the Pt precursor and Pt loading, which caused huge differences in their activity and isomer selectivity. The Pt dispersion in the enhanced activity catalysts was also much lower. A careful optimization of the precursor, amount of Pt loaded, and pretreatment conditions is essential to achieve good balance between the metal and the acid functions in these catalysts. The optimized enhanced activity catalyst is able to provide isomer yields approaching that obtained over the regular catalysts, which suggests that zeolite acidity is not directly affecting the isomer selectivity. These results indicate that the maximum isomer yield for a Pt/H-zeolite catalyst is obtained when the metal and acidic functions of the catalysts are well balanced. Therefore, it may not be possible to increase the isomer yield beyond this maximum by modifying the acidity characteristics of the catalyst. Mordenite and ZSM-5 catalysts showed low isomer yields, but acid dealumination of the parent mordenite improved the isomer yield, possibly due to creation of mesopores. [Copyright &y& Elsevier]