[Preparation and the properties of a highly purified preparation of myosin from smooth muscles].

Myosin was isolated from the smooth muscles of small intestine of calf with good yield and its properties were compared with the myosin's properties from the skeletal rabbit muscle. The crude myosin was purified by means of DEAE-cellulose column chromatography, using a KCl gradient. The purity of the preparations was checked spectrophotometrically by the densities of adsorption D280/D260, viscosimmetrically by the sensitivity to ATP, electrophoretically and by ultracentrifugation. By the above-mentioned properties the smooth muscle myosin was similar to the high-purified skeletal muscle myosin. A comparative study of the enzymatic properties of myosin from two types of tissues, showed the following differences: (1) in the dependence the Ca2+-ATPase activity on the KCl concentration in the incubation medium; (2) in the degree of myosin activation by actin in the presence of Mg2+; (3) in the behaviour of Ca2+-ATPase dependence on pH; (4) the different temperature optima of the ATPase activity.