Expression, purification and biophysical characterization of recombinant Streptomyces violaceoruber phospholipase PLA2 overproduced in Pichia pastoris.

Aim: The main purpose of this work was to develop new protocols for high yield purification of secretory phospholipase A2 (PLA2) and to investigate its biophysical properties.Materials and methods: We have used a Pichia pastoris expression system for PLA2 expression and two-stage chromatography for its purification. The biophysical properties of PLA2 were investigated by circular dichroism.Results: A scalable method for high yield purification of recombinant Streptomyces violaceruber PLA2 was developed. The PLA2 from S. violaceruber was expressed in the methylotrophic yeast P. pastoris. Functional active phospholipase A2 with specific activity 73 U/mg was purified with a concentration of at least 3 mg/mL. The role of different divalent ions in PLA2 thermostability were evaluated. Ca2+ and Ba2+ ions significantly increased thermostability of the enzyme.

[Development of an Immunochromatographic Test System for the Detection of Helicobacter pylori Antigens].

A test system based on immunochromatography in the sandwich format and intended for express detection of Helicobacter pylori antigens has been developed. Contact of a sample with a test strip coated with immunochemical reagents triggers the movement of the liquid along the membrane components of the test strip, immunochemical interactions, and the formation of detection zones stained by gold nanoparticles. The concentration and kinetic dependences of the immunochemical interactions have been characterized. The reagent and membrane composition of the test system has been selected to provide a minimal detection limit. The detection of H. pylori cell wall antigens at concentrations as low as 0.3 µg/mL in aqueous solution and a suspension of a clinical sample of feces has been demonstrated; the assay duration was 10 minutes. Staining enhancement by the addition of silver salts allowed for a further reduction of the detection limit to 0.03 µg/mL. The developed test system can be used for field diagnostics.

The role of ala198 in the stability and coenzyme specificity of bacterial formate dehydrogenases.

It has been shown by an X-ray structural analysis that the amino acid residues Ala198, which are located in the coenzyme-binding domain of NAD(+)-dependent formate dehydrogenases (EC 1.2.1.2., FDH) from bacteria Pseudomonas sp.101 and Moraxella sp. C-1 (PseFDH and MorFDH, respectively), have non-optimal values of the angles ψ and φ. These residues were replaced with Gly by site-directed mutagenesis. The mutants PseFDH A198G and MorFDH A198G were expressed in E.coli cells and obtained in active and soluble forms with more than 95% purity. The study of thermal inactivation kinetics showed that the mutation A198G results in a 2.5- fold increase in stability compared to one for the wild-type enzymes. Kinetic experiments indicate that A198G replacement reduces the KM (NAD+) value from 60 to 35 and from 80 to 45 µM for PseFDH and MorFDH, respectively, while the KM (HCOO-) value remains practically unchanged. Amino acid replacement A198G was also added to the mutant PseFDH D221S with the coenzyme specificity changed from NAD(+) to NADP(+). In this case, an increase in thermal stability was also observed, but the influence of the mutation on the kinetic parameters was opposite: KM increased from 190 to 280 µM and from 43 to 89 mM for NADP(+) and formate, respectively. According to the data obtained, inference could be drawn that earlier formate dehydrogenase from bacterium Pseudomonas sp. 101 was specific to NADP(+), but not to NAD(+).

[The application of proteomic technologies for the analysis of muscle proteins of farm animals used in the meat industry (review)].

The review briefly summarizes the data on the development of proteomic technologies that became actively used in studies of the muscular proteins of farm animals used in the meat industry in 2006-2013. It has been noted that the main research trends are connected with the detection of changes in muscle proteins during post-mortem autolysis and the search for species-specific and other protein biomarkers. Particular publications regarding the development of methods based on proteomic technologies for monitoring the state of muscle proteins are considered. According to the analyzed data, we can conclude that the field is promising for the solution of a number of pressing problems in.applied biochemistry.

"Prostate cancer proteomics" database.

A database of Prostate Cancer Proteomics has been created by using the results of a proteomic study of human prostate carcinoma and benign hyperplasia tissues, and of some human-cultured cell lines (PCP, http://ef.inbi.ras.ru). PCP consists of 7 interrelated modules, each containing four levels of proteomic and biomedical data on the proteins in corresponding tissues or cells. The first data level, onto which each module is based, is a 2DE proteomic reference map where proteins separated by 2D electrophoresis, and subsequently identified by mass-spectrometry, are marked. The results of proteomic experiments form the second data level. The third level contains protein data from published articles and existing databases. The fourth level is formed with direct Internet links to the information on corresponding proteins in the NCBI and UniProt databases. PCP contains data on 359 proteins in total, including 17 potential biomarkers of prostate cancer, particularly AGR2, annexins, S100 proteins, PRO2675, and PRO2044. The database will be useful in a wide range of applications, including studies of molecular mechanisms of the aetiology and pathogenesis of prostate diseases, finding new diagnostic markers, etc.

Structures of the apo and holo forms of formate dehydrogenase from the bacterium Moraxella sp. C-1: towards understanding the mechanism of the closure of the interdomain cleft.

NAD(+)-dependent formate dehydrogenase (FDH) catalyzes the oxidation of formate ion to carbon dioxide coupled with the reduction of NAD(+) to NADH. The crystal structures of the apo and holo forms of FDH from the methylotrophic bacterium Moraxella sp. C-1 (MorFDH) are reported at 1.96 and 1.95 A resolution, respectively. MorFDH is similar to the previously studied FDH from the bacterium Pseudomonas sp. 101 in overall structure, cofactor-binding mode and active-site architecture, but differs in that the eight-residue-longer C-terminal fragment is visible in the electron-density maps of MorFDH. MorFDH also differs in the organization of the dimer interface. The holo MorFDH structure supports the earlier hypothesis that the catalytic residue His332 can form a hydrogen bond to both the substrate and the transition state. Apo MorFDH has a closed conformation of the interdomain cleft, which is unique for an apo form of an NAD(+)-dependent dehydrogenase. A comparison of the structures of bacterial FDH in open and closed conformations allows the differentiation of the conformational changes associated with cofactor binding and domain motion and provides insights into the mechanism of the closure of the interdomain cleft in FDH. The C-terminal residues 374-399 and the substrate (formate ion) or inhibitor (azide ion) binding are shown to play an essential role in the transition from the open to the closed conformation.

[A comparative study of the thermal stability of formate dehydrogenases from microorganisms and plants].

A comparative study of the thermostability of NAD+-dependent formate dehydrogenases (FDHs; EC 1.2.1.2) from both methylotrophic bacteria Pseudomonas sp. 101 and Moraxella sp. Cl, the methane-utilizing yeast Candida boidinii, and plants Arabidopsis thaliana and Glycine max (soybean) was performed. All the enzymes studied were produced by expression in E. coli cells. The enzymes were irreversibly inactivated in one stage according to first-order reaction kinetics. The FDH from Pseudomonas sp. 101 appeared as the most thermostable enzyme; its counterpart from G. max exhibited the lowest stability. The enzymes from Moraxella sp. Cl, C. boidinii, and A. thaliana showed similar thermostability profiles. The temperature dependence of the inactivation rate constant of A. thaliana FDH was studied. The data of differential scanning calorimetry was complied with the experimental results on the inactivation kinetics of these enzymes. Values of the melting heat were determined for all the enzymes studied.