[Effects of biogenic and abiogenic disulphides upon endothelial cells in culture: comparison of three methods of viability assessment].

Effects of biogenic and abiogenic disulphides on viability of human umbilical vein endothelial cells in culture has been investigated using three methods: the neutral red uptake assay, quantification of intracellular ATP, and modifications of Mosmann method, the essence of which is the reduction of tetrazolium salts, MTT and MTS, by cells. 2,2'-dithio-bis(N,N-diethyl)ethanamine (DS) was used as an abiogenic disulphide. As for biogenic disulphides, we used GSSG and garlic oil (GO), the principal component of which is diallyl disulphide (DADS). It has been found that DS and GO have a similar cytotoxic effect upon the endothelial cells (EC50 - 0.6 mM). GSSG in concentrations up to 1 mM did not effect the viability of endothelial cells. It has been demonstrated for the first time that DS and GO can serve as mediators of plasma membrane oxidoreductase activity, tetrazolium salts being as the substrate; this may cause false-negative effect. Thus, the Mosmann method has serious limitations when testing the cytotoxicity of disulphides, though can be used in studying the mechanism of action of disulphides.

[Serum albumin: search for new sites with esterase activity according to molecular modeling data].

It is known that albumin is able to cut ester bonds in organophosphates (OPs). Amino acids responsible for esterase and pseudo-esterase activity of albumin towards OPs are still not determined. The purpose of this study is to identify the potential sites of esterase activity of albumin by the example of its interaction with soman using molecular modeling methods. The structures of the protein complexes with soman was determined by molecular docking procedure, the stability of the complexes were simulated using molecular dynamics method. It has been determined that productive sorption of soman near Tyr411 is possible only after deprotonation of the tyrosine. Tyr150 binds soman more efficiently than Tyr411; deprotonation of Tyr150 does not affect the binding efficiency, but affects on the stability of the complexes. The true esterase activity of albumin Tyr150 in relation to soman is proposed. It is shown that Ser193 can also be responsible for the esterase activity of albumin. We hypothesize that deprotonation of catalytic amino acid in one of the sites could be initiated by ligand binding in other sites (allosteric regulation).

[New approaches to early diagnosis of chronic organophosphorus chemicals intoxication in workers at chemical weapons extermination objects].

Mass spectrum analysis revealed differences in general contents of low-molecular peptides spectrums in chemical weapons extermination object staffers, in comparison with the reference group. Findings are that serum paraoxonase activity in chemical weapons extermination object staffers in significantly increased.