[Effect of temperature on superprecipitation of actomyosin of myometrial smooth muscle and reactions of ATP hydrolysis catalyzed by this protein].

The experiments carried out on the preparation of myometrium actomyosin were carried out. The reaction of superprecipitation of this protein and ATP hydrolysis were studied as affected by temperature. For the both processes the value of temperature optimum is 45 degrees C. The value of activation energy Ea is equal to 20 +/- 3 and 23 +/- 3 kJ/mol for the reaction of superprecipitation and ATP hydrolysis, respectively. Preincubation of actomyosin (45-60 degrees C, 1-5 min) in the medium not including ions of Ca, Mg and ATP with following introduction of the components to this medium and ten-minute incubation of protein in it causes the inhibition of the both reactions at the incubation temperature 45 degrees C and their stimulation at the incubation temperature 55 and 60 degrees C. Data obtained are discussed with regard for the structure organization of actomyosin of the smooth muscle.