Effect of Temperature on Mg-ITP-induced Superprecipitation of Actomyosin

抄録

Superprecipitation of an actomyosin suspension was measured at various temperatures (2.5°-20°) using Mg-ITP as substrate. Superprecipitation was induced by the addition of Mg-ITP at all temperatures, but decreased in extent with decrease in temperature. The predominant intermediate in the Mg-ITP hydrolysis of myosin depends on the temperature; at 20° it is the myosin^*-IDP-Pi complex, while below 8° it is the myoisn-ITP complex (Hozumi, T. (1976) Eur. J. Biochem. 63, 241). Therefore, the occurrence of superprecipitation below 8° is not compatible with muscle models in which formation of a myosin^*-product complex is the rate-limiting intermediate.