| Abstract: | The reaction of trinitrobenzenesulfonate with gizzard myosin was studied. The initial phase of the reaction involved two residues and at this level of modification the following was observed: the Mg2+-ATPase of myosin, the actin-activated ATPase of phosphorylated myosin and the phosphorylation kinetics of myosin were not affected. However, trinitrophenylation did induce an activation of the actin-activated ATPase of dephosphorylated myosin and in this respect mimicked the effect of light chain phosphorylation. The Mg2+-dependence of actin-activated ATPase also is altered on trinitrophenylation. These alterations of enzymatic properties could be at least partly explained by the finding that trinitrophenylation favored the 6S conformation of myosin. |
