[Use of differences in substrate inhibition for determination of the interrelationship between molar fractions of lactate dehydrogenase subunits].
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.
D002384:Catalysis; D055598:Chemical Phenomena; D002621:Chemistry; D006801:Humans; D007527:Isoenzymes; D007700:Kinetics; D007770:L-Lactate Dehydrogenase
D007527:Isoenzymes; D007770:L-Lactate Dehydrogenase
Ispol'zovanie razlichiĭ v substratnom ingibirovanii dlia opredeleniia sootnosheniia mol'nykh doleĭ sub"edinits laktatdegidrogenazy