CHANGE OF SIZE AND SHAPE OF MYOSIN B BY POLYPHOSPHATE*) By

SZENT·GyORGYII) and NEEDHAM et al! ' have found that the viscosity and the flow.birefringence of the solution of the muscle contractile protein, myosin B, decrease on the addition of polyphosphate such as A TP or PP. Sj':ENT·GYORGYI') has demonstrated that the complex protein, actomyosin, constituted by F·acrin and myosin A, shows similar properties to those of myosin B, and SZENT·GYORGYIl) and WEBER"') have investigated the contraction of muscle models by ATP. Through these studies it has been generally accepted that muscle contraction is caused by the interaction between myosin, actin and ATP.""·) The size and shape change of myosin B with A TP or PP, which may be one of the most important reactions in the mechanism of muscle contraction, has been investigated by many workers. such as WEBER' " MORALES"ll, GERGELy,,8!, MOMMAERTS9,lO) and USH'. But the mechanism of this important reaction remains to be clarified in many points. Then we have engaged in systematic study on the change of size and shiltpe of myosin B by PP, which produces same effect on myosin B as A TP doe