COMPARATIVE STUDIES ON SUPERPRECIPITATION OF CARDIAC AND SKELETAL MYOSIN B

The superprecipitation of cardiac myosin B involved smaller turbidity changes, was inhibited by lower KCl and MgATP concentrations and abolished by a much shorter trypsin digestion time than that of the skeletal myosin B. Polyethylene glycol having a mol wt of 4000 decreased the solubilizing effect of KCl on the myosin B suspensions and significantly extended the optimal KCl and MgATP concentration range for superprecipitation with both myosin B. In the presence of this compound the differences between the superprecipitation of the cardiac and skeletal myosin B either disappeared or significantly diminished. The results were discussed in connection with some known differences in the conformation of cardiac and skeletal myosin A. © 1969.