A novel alkaline proteinase associated with the actomyosin complex from pig uterine myometrium

A novel proteolytic activity has been demonstrated an partially characterized in the actomyosin complex isolated from smooth uterine muscle. This proteolytic activity showed an alkaline pH optimum, was inhibited by SH-group-blocking reagents but not by metal-chelating agents and copurified with the actomyosin complex. An important characteristic of this alkaline proteolytic activity was that it seems to hydrolyze the actomyosin by limited proteolysis with a concomitant loss of the myosin adenosinetriphosphatase activity.