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It has been shown that the synthetic lipophilic anion, sodium tetraphenylboron, used at concentrations up to 15 mM causes modification of high density lipoproteins (HDL) by changing the electrophoretic properties of individual lipoprotein subclasses. The densitograms obtained after separation of sodium tetraphenylborate-modified HDL under non-denaturing conditions have a better resolution with respect to subclasses 2a and 2b, which markedly facilitates the analysis of the subfractional composition of lipoproteins.

Differential binding of lipophilic permeant anion-tetraphenylboron by high density lipoproteins is shown. The electrochemical heterogeneity of lipoproteins is explained by the difference in their protein-lipid content.

An addition of tetraphenylboron (TPB) at low values of pH results in the formation of a cholesterol-rich pellet after centrifugation. The pellet contains 90-95% of whole serum cholesterol. The pH effectiveness sequences for TPB precipitation of low density lipoproteins are detected. It is assumed that TPB changes the distribution of the charges in the hydrophobic moiety of lipoproteins and increases their ability to precipitate.

The interaction of human creatine phosphokinase isoenzymes with rabbit antibodies and their Fab has been studied. It has been shown that Fab of the antibodies against MM or BB isoenzymes preserve high specificity of intact antibodies and the ability to inhibit creatine kinase isoenzymes. Differences between antibodies and their Fab have been found to exist with respect to the kinetics of binding with homologous isoenzymes: the rate of the complex formation for Fab is significantly higher. The interaction of creatine kinase isoenzymes with intact antibodies and their Fab is not affected by the addition of creatine kinase substrates. The antibodies against MM and BB isoenzymes have been used to study the individual properties of each subunit of the M- and B-type in a hybrid dimer MB. It has been shown that such properties of these subunits as the Michaelis constants, pH dependence and inhibition by homologous antibodies are identical to those of non-hybrid MM and BB isoenzymes, respectively.

A kinetic method of estimating the ratio of mole quota of H and M human lactate dehydrogenase (LDG) subunits is proposed, based on changes in substrate inhibition of LDG isoenzymes with lactate. Stability of kinetic constants for a long period of time is demonstrated. The dependency of activities ratio under low and high substrate concentration on the contribution of mole quota of LDG M subunits is studied. The correlation of experimental and theoretical values is shown to be: r=0.998 p less than 0.001. A comparison is carried out of the content of LDG subunits molar quotas in artificial mixtures with electrophoretic experimental data, a good coinsidence of these values being registered. The informative importance of the method described with standard methods of the estimation of LDG isoenzyme systems is discussed. No effect of components of human diploid cells homogenate and an insignificant effect of blood serum components on kinetic constants of LDG isoenzymes is registered. A dependency of variation coefficients on the enzyme activity is studied, minimal omegan value being 0.6%. The applicability of the method described for the calculation of quantitative content of both LDG subunits in natural objects (blood serum, diploid cell homogenate etc.) is demonstrated.

Properties of human creatine kinase isoenzymes (MM, MB and BB) are investigated. The most pronounced differences in properties of these isoenzymes are found under their urea inactivation, heat denaturation and the inhibition by rabbit antisera to isoenzymes. Differences in values of the Mikhaelis constant and substrate and pH dependencies are much less pronounced. The presence of ADP stabilizes creatine kinase isoenzymes under conditions of urea and heat inactivation. Properties of hybrid MB isoenzymes are found to be intermediate with respect to MM and BB isoenzymes. A mode of the interaction of M and B subunits in dimeric molecules of creatine kinase isoenzymes is discussed.

Interrelations of active sites of tetrameric molecules of human lactatedehydrogenase (LDH), known as intratetrameric catalytic independency of subunits, are studied. Estimation of catalytic activity of subunits, which compose hybrid LDH isoenzymes, is carried out. Ratios of molecular activity of subunits are calculated and a conclution is drawn on the catalytic independency of LDH isoenzymes active sites with respect to substrate inhibition by L-lactate. Possible mechanisms of substrate inhibition of LDH isoenzymes and their inactivation with urea in the view of different interrelations of active sites of these isoenzymes under conditions studied are discussed.