[Kinetic properties of skeletal muscle sarcolemmal Ca2+-ATPase].
Calcium activation of skeletal muscle sarcolemma Ca2+-ATPase is investigated. The investigation of a dependency of the initial rate of ATP hydrolysis on total concentration of substrate and on total and free calcium concentrations showed that the role of calcium ions is not limited by the formation of the substrate complex (CaATP2-). Calcium is absolutely necessary for the enzyme transition from inactive into active form. The inhibitory effect of free ATP is due to a decrease of free calcium concentration as a result of complexation with ATP, but not of competition with substrate in the active site. It is shown also that magnesium competitively inhibits the interaction of the enzyme with the substrate and non-competively suppress the activation of Ca2+-ATPase by free calcium.
D000251:Adenosine Triphosphatases; D000818:Animals; D002118:Calcium; D002384:Catalysis; D004789:Enzyme Activation; D007700:Kinetics; D009132:Muscles / Q000201:enzymology*; D011817:Rabbits
D000251:Adenosine Triphosphatases; D002118:Calcium
O kineticheskikh svoĭstvakh Ca2+-ATPazy sarkolemmy skeletnykh myshts