Purification and some properties of rabbit stomach myosin

Myosin from rabbit stomach was highly purified by ammonium sulfate fractionation in the presence of ATP and MgCl2, ultracentrifugation and Sepharose 4B chromatography. The myosin composed of one heavy and two light chains as determined by SDS-gel electrophoresis. The molecular weights of the light chains were the same as those of gizzard myosin, about 20,000 and 17,000, respectively. The pH-activity curve and the KCl concentration dependency of Ca-ATPase of the stomach myosin were similar to those of other smooth muscle myosins. The stomach myosin was more resistant to pepsin digestion than skeletal myosin. Other proteolytic enzymes, trypsin, chymotrypsin, papain, and nagarse, digested the myosin in the same way as skeletal myosin.