Lipolysis drives expression of the constitutively active receptor GPR3 to induce adipose thermogenesis

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Immunoenzyme method of sequential saturation for determining antigens using the model of insulin

The method for the determination of insulin by means of the enzyme immunoassay, based on the use of insulin-peroxidase conjugates, has been developed. In this assay the scheme of the successive saturation of the active sites of antibodies is used. The antigenic properties of two conjugates differing in the method of their preparation are compared. The conjugates were obtained by the covalent binding of peroxidase, oxidized in its carbohydrate component, with insulin (conjugate 1) or hexamethylene-diamine-modified insulin (conjugate 2). The conjugates represented a mixture of oligomers differing in their molecular weight. Conjugate 1 possessed higher affinity to antibodies and higher enzymatic activity than conjugate 2. The method for evaluating the quality of antisera to insulin used in the assay has been proposed. The time of the insulin assay is 5-16 hours, the limit of insulin detection is 5 microU/ml, the variation factor is 3-12%.     

Elongation factor Tu can reduce translation errors in poly(U)-directed cell-free systems

Rates of incorporation of [³H]phenylalanine and [¹⁴C]leucine from the aminoacylated transfer-RNA into polypeptides synthesized on poly(U) programmed Escherichia coli ribosomes have been determined in cell-free translation systems containing either elongation factors Tu and G with GTP, or just elongation factor Tu or G with GTP, or none of the elongation factors. The presence of elongation factor Tu with GTP has been shown to reduce the leucine to phenylalanine ratio in the product at relatively low concentrations of Mg²⁺. This error-reducing effect of elongation factor Tu has not been observed at high concentrations of Mg²⁺, although the factor still contributed to the speed of elongation. The results are discussed in terms of the kinetic proof-reading mechanism proposed by Hopfield (1974).     

Facilitation of the structural and functional disorders of liver lysosomes in toxic hepatitis due to the suppression of intralysosomal proteolysis

Suramin that accumulates in rat liver Kupffer cell lysosomes and inhibits the intralysosomal proteolysis was used to suppress the functional activity of these particles during liver damage (acute CCl4 hepatitis). Polyvinylpyrrolidone that does not disturb protein catabolism in liver lysosomes was employed for reference. According to the characteristic changes in lysosomes induced by suramin (inhibition of acid phosphatase, decrease of the rate of the intralysosomal proteolysis in the liver) and PVP the damaged liver was able to accumulate the lysosomotropic substances under study. Suramin aggravated liver damage and increased the lysosomal labilization, whereas PVP exhibited the protective action. The unfavourable effect of suramin may be linked with the suppression of catabolism of Kupffer cell lysosomes. The data obtained suggest the lack of safety of using the inhibitors of intralysosomal proteolysis in patients with acute hepatitis.     

The mechanism of cathode reduction of oxygen in a carbon carrier-laccase system

The influence of temperature, oxygen pressure and inhibitors of laccase on the dioxygen electroreduction reaction has been examined at different solution pH. On the basis of obtained data, a reaction mechanism including electron transfer from the enzyme active site to the oxygen molecule is suggested as the slow step.