3H-31, A Non-structural Protein of Heliothis virescens ascovirus 3h,Inhibits the Host Larval Cathepsin and Chitinase Activities

Virologica Sinica - 3h-31 of Heliothis virescens ascovirus 3h (HvAV-3h) is a highly conserved gene of ascoviruses. As an early gene of HvAV-3h, 3h-31 codes for a non-structural protein (3H-31) of...     

Bounded water kinetic model of β-galactosidase in reverse micelles

In the present investigation, -galactosidase was solubilized into Aerosol OT (AOT)/isooctane reverse micelles. Kinetic data for the hydrolysis of o-nitrophenyl--D-galactopyranoside (ONPG) at different pH values and molar ratios of water to AOT (W_o) were collected. It was observed that the usual kinetic model used for -galactosidase catalysis in aqueous systems failed to represent the experimental data. A bounded water model, however, showed a better correlation between enzymatic activity and W_o. In contrast to the aqueous system, controlling the water concentration in the reverse micelles allows the rate constants for the reaction between water molecules and glycosyl-enzyme complexes to be evaluated.     

Flexoelectric origin of nanomechanic deflection in DNA-microcantilever system

The membrane theory is used to study the recently observed nanomechanical bending of cantilevers, which have processed biomolecular adsorption or biochemical reactions. To be different from entropy-controlling bending mechanism discussed before, we propose that the flexoelectric effect induces cantilever bending. With the introduction of flexoelectric spontaneous curvature, the relation between the bending and biopolymer character is constructed by a simple analytical formula. The cantilever motion induced by adsorption of single-strand DNA and DNA hybridization reaction is quantified analytically and our results show good agreement with experiments.     

Affinity and Specificity of Ciprofloxacin-Bovine Serum Albumin Interactions: Spectroscopic Approach

Fluorescence spectroscopy in combination with UV–Vis absorption spectroscopy were employed to investigate the binding of an antibacterial drug Ciprofloxacin (CPFX) to bovine serum albumin (BSA) under the physiological conditions. In the discussion of the quenching mechanism, it was proved that the fluorescence quenching of BSA by CPFX is a result of the formation of CPFX-BSA complex. Binding parameters were determined using the modified Stern-Volmer equation and Scatchard equation to provide a measure of the binding affinity between CPFX and BSA. The results of thermodynamic parameters ΔG, ΔH, ΔS, at different temperatures indicate that the electrostatic interactions play a major role for CPFX-BSA association. Site marker competitive experiments indicated that the binding of CPFX to BSA primarily took place in site I. Furthermore, the effect of metal ions to CPFX-BSA system was studied, and the distance r between donor (BSA) and acceptor (CPFX) was obtained according to fluorescence resonance energy transfer (FRET). The conformation of BSA upon CPFX binding was evaluated by measuring synchronous fluorescence properties of the CPFX-BSA complex.     

Biological Activation of Heteropoly Complex of Molybdotungstosilicate Containing Lanthanum K10H3La(SiMo6W5O39)2⋅26H2O: Spectroscopic Approach and Microcalorimetry

In this paper, the biological activation of heteropoly complex of molybdotungstosilicate containing lanthanum K₁₀H₃La(SiMo₆W₅O₃₉)₂?26H₂O (LaW₅) was investigated by spectroscopic approach and microcalorimetry under the human physiological conditions. Fluorescence spectroscopy in combination with UV–Vis absorption spectroscopy was employed to investigate the binding of LaW₅ to bovine serum albumin (BSA). In the mechanism discussion, it was proved that the fluorescence quenching of BSA by LaW₅ is a result of the formation of LaW₅–BSA complex. Binding parameters were determined using the Stern–Volmer equation. The results of thermodynamic parameters ?G, ?H, ?S at different temperatures indicate that van der Waals interactions and hydrogen bonds play a major role for LaW₅–BSA association. The distance r between donor (BSA) and acceptor (LaW₅) was obtained according to fluorescence resonance energy transfer. Furthermore, the calorimetric method was used to monitor the biological activity of LaW₅ in Escherichia coli.     

The study of anti-metabolic syndrome effect of puerarin in vitro

Puerarin is an isoflavone extracted from Chinese plant, Pueraria lobata (Wild.) Ohwi. It has been reported to have comprehensive pharmacological action in treatment of diabetes and cardiovascular diseases. The purpose of this study was to link the scattered effects of puerarin and to find the common mechanisms underlying. We investigated the effect of puerarin on the pivotal common pathogenic factors of metabolic syndrome, which includes obesity, Type II diabetes and cardiovascular diseases. Recently, a large body of evidence indicates that there is a complicated interplay among insulin resistance, adipocytes and endothelial dysfunction that links the abnormalities of metabolic syndrome. Results of present study showed that puerarin could potentiate insulin-induced preadipocyte differentiation, promote glucose-uptake of adipocytes that have been induced insulin resistance by high glucose, and prevent TNF-a-induced apoptosis and viability loss of endothelial cells. Furthermore, we found that these effects are probably due to promote PPARgamma expression and partly through inhibiting abnormal TNF-a-induced intracellular-free Ca(2+) accumulation of endothelial cells. Overall, our synthetical study links the comprehensive pharmacological actions of puerarin to the recognized common pathogenesis of metabolic syndrome, and provides a new insight into the mechanism of puerarin effect.     

Sequence analysis and structural prediction of the severe acute respiratory syndrome coronavirus nsp5

The non-structural proteins (nsp or replicase proteins) of coronaviruses are relatively conserved and can be effective targets for drugs. Few studies have been conducted into the function of the severe acute respiratory syndrome coronavirus (SARS-CoV) nsp5. In this study, bioinformatics methods were employed to predict the secondary structure and construct 3-D models of the SARS-CoV GD strain nsp5. Sequencing and sequential comparison was performed to analyze the mutation trend of the polymerase nsp5 gene during the epidemic process using a nucleotide-nucleotide basic local alignment search tool (BLASTN) and a protein-protein basic local alignment search tool (BLASTP). The results indicated that the nsp5 gene was steady during the epidemic process and the protein was homologous with other coronavirus nsp5 proteins. The protein encoded by the nsp5 gene was expressed in COS-7 cells and analyzed by sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE). This study provided the foundation for further exploration of the protein‘s biological function, and contributed to the search for anti-SARS-CoV drugs.     

Ethanol fermentation in a magnetically fluidized bed reactor with immobilized Saccharomyces cerevisiae in magnetic particles

Ethanol fermentation by immobilized Saccharomyces cerevisiae cells in magnetic particles was successfully carried out in a magnetically stabilized fluidized bed reactor (MSFBR). These immobilized magnetic particles solidified in a 2 % CaCl(2) solution were stable and had high ethanol fermentation activity. The performance of ethanol fermentation of glucose in the MSFBR was affected by initial particle loading rate, feed sugar concentration and dilution rate. The ethanol theoretical yield, productivity and concentration reached 95.3%, 26.7 g/L h and 66 g/L, respectively, at a particle loading rate of 41% and a feed dilution rate of 0.4 h(-1) with a glucose concentration of 150 g/L when the magnetic field intensity was kept in the range of 85-120 Oe. In order to use this developed MSFBR system for ethanol production from cheap raw materials, cane molasses was used as the main fermentation substrate for continuous ethanol fermentation with the immobilized S. cerevisiae cells in the reactor system. Molasses gave comparative ethanol productivity in comparison with glucose in the MSFBR, and the higher ethanol production was observed in the MSFBR than in a fluidized bed reactor (FBR) without a magnetic field.