ON THE KINETICS OF ENZYMATIC PROCESSES IN SOILS
Kinetic parameter values of enzyme activity in the genetic soil series of the Cis-Urals have been measured based on the Michaelis constant (Km), maximum velocity (Vmax), temperature coefficient (Q10), activation energy (E) and activation enthalpy (H) that characterize the reaction rate depending on the characteristics of enzymes and environment conditions. In soils Km is more stable than Vmax, and according to these parameters chernozems are closely related. The Km value of soil enzymes resembles that of microorganisms. Thermodynamic constants of enzymatic reactions in the range of 10-50C differ in genetically different soils. It is supposed that at low temperatures the reaction involves mostly free and labile-bound enzymes, and with a rise in temperature immobilized enzymes that prevail in the soil are activated being characterized by high activation energy. The pattern of changes in the kinetic parameters attests to heterogeneity of soil enzymes both by their state (free and bound) and composition as well as to their identity by the state and composition in genetically close soils and their primarily microbial origin.