Studies on the interaction of actomyosin with polyions

Abstract

Electrophoretic experiments showed that PS 3 adsorbed to actomyosiri at pH 7.5 diminished the net negative charge on these suspensions. PS also reversed the clearing effect of 6.6 × 10 −5 m ATP on actomyosin to superprecipitation in solutions containing 0.132 to 0.165 m KC1 and 3.3 × 10 −5 m Mg 2+ at pH 7.5. PES increased the net negative charge on actomyosin suspensions and transformed the 6.6× 10 −5 m ATP induced superprecipitation to clearing in solutions containing 0.099 m KC1 and 3.3 × 10 −5 m Mg 2+. In 0.099 m KC1 solution at pH 7.5 the ATP concentration range for superprecipitation was much wider with PS and significantly narrower with PES than without these polyions. The superprecipitation and clearing reaction is explained as depending upon the relative influence of complimentariness on the part of the interacting protein surfaces (attracting forces), the existing net surface charge on the actomyosin suspension (repelling forces), and the extent of the local discharging effect of the adsorbed ATP (1).No correlation appears to exist between ATPase activity and the super-precipitation-clearing reaction in the presence of some polyions.