[A granulopoiesis inhibitor. Synthesis and biological activity].

Three schemes of synthesis for pentapeptide Glp-Glu-Asp-Cys-Lys-OH were compared was carried out. Acetamidomethyl protection was used for the mercapto group of cysteine. For the same purpose, cystine was used as the starting compound for synthesis.

[Immunoenzyme method of determining trace amounts of proinsulin in recombinant human insulin].

An enzyme immunoassay (ELISA) for the detection of human proinsulin has been developed based on the interaction of the absorbed proinsulin with the antiserum against the synthetic proinsulin C-peptide. In the presence of high concentrations of insulin, the sensitivity of the assay slightly decreases due to the competitive adsorption of insulin onto the polystyrene carrier with the binding constant 800-1000 times less than that of proinsulin. A method is proposed for the interpretation of ELISA data based on analysis of a weighed dry insulin sample, which enables the detection of a 0.

[Use of arylsulfenylchlorides for cleaving fibrinogen at methionine residues].

Conditions for the fibrinogen fragmentation with 2-pyridyl-or o-nitrophenylsulfenylchloride were proposed. Resulting mixture of fragments is identical to the mixture prepared by the cyanogen bromide treatment and is suitable as supplementary analytical reagent in the determination of the tissue plasminogen activator (TPA) activity with a chromogenic substrate.

[The heterogeneous character of protein modification during substitution of their amino groups. Acylation of alpha-chymotrypsin].

Thin-layer isoelectric focusing of chymotrypsin modified by stepwise acylation with acryloyl chloride or maleic anhydride revealed a high heterogeneity of modification products, with a maximal number of components near 50% of substituted amino groups. Disc electrophoresis failed to establish the products diversity and could not therefore be used for heterogeneity control. The activity of the modified enzyme towards proteins and low molecular weight substrates depended on the modification reagent and correlated with the electrostatic enzyme--substrate interaction.