[Role of low molecular weight metabolites as natural regulators of metabolism].

The paper presents results of scientific activity of the Department of Metabolism Regulation. The main sections are: carbamates formation and their role in metabolism regulation; metabolic system of acid-base homeostasis in animals; polyamines metabolism in the extremal states; mechanisms of metabolic adaptation in mammals. Experimental data are presented which evidence for the fact that tissue proteins in vivo are subjected to nonenzymic carboxylation with formation of carbominic groups. In this case a charge variation in definite sites of protein molecule is observed, which specifies variation of the protein conformation and biological properties. Basic regularities of protein carbamate formation reactions are revealed with factors affecting their intensity. It is shown that the presence of carbonic acid in the medium increases the rate of reactions catalyzed with lactate dehydrogenase from the rabbit liver, glucose-6-phosphate dehydrogenase from yeast and trypsin. Under the same conditions the reaction velocity rate catalyzed with glucose-6-phosphate dehydrogenase from the rabbit liver and with ATP-citrate (pro-35)-liase is considerably decreased. Changes in the concentration of carbonic acid within the physiological limits are found to have no effect on lactate dehydrogenase from the cattle heart and chymotrypsin. The rate of the reaction catalyzed by NAD-dependent malate denydrogenase was studied as affected by carbon dioxide. It is shown that acceleration of the catalysis in these systems depends on the presence of both a bicarbonate anion and soluble carbon dioxide. IR spectra of NAD-dependent malate dehydrogenase in the deuterium oxide solutions were studied in the CO2-free solutions and solutions saturated with it.(ABSTRACT TRUNCATED AT 250 WORDS)