| Abstrakt: |
Factors affecting inhibition of myosin ATPase by ATP, such as concentration of the enzyme, of ATP, and of the divalent metals, calcium and magnesium, have been studied and the results are reported here. Experiments were carried out under conditions in which no known magnesium effects occurred, so that only the effect of calcium on the nucleoside triphosphatase activity of myosin A could be qualitatively characterized. Myosin A ATPase was inhibited by free ATP at 0.15 ionic strength in the presence of millimolar calcium and 0.006 mKCl. A reaction model is proposed in which Ca-ATP is the substrate for native myosin A and inhibition is brought about by 2 moles of ATP. |
