[Heterogeneous and kinetic analysis of certain properties of Ca2+-ATPase in sarcolemma of rabbit skeletal muscles].

Kinetic properties of Ca2+-ATPase were studied by means of the continuous potentiometric method. On the basis of heterogenous and kinetic ideas it is shown that the experimental data on the effect of ions CA2+ on the Ca2+-ATPase activity may be explained, assuming the chelate complex Ca-ATP2- to be a substrate of the enzyme. The results obtained show that if the chelate complex formed in the aqueous stage is a substrate, then, a competition for adsorption at the active centre is possible between Ca-ATP2- and ATP4- but not between Ca-ATP2 and Ca2+. If the substrate is the chelate complex formed directly at the active centre, then ATP4- and the enzyme must combine through ion Ca2+ according to the scheme: enzyme - Ca2+ - ATP4-.