Studies on adductor muscle proteins of the scallop. III. Isolation and characterization of actin.

Abstract

Actin was isolated from the smooth adductor of scallop Patinopecten yessoensis as follows. The crude natural actomyosin was prepared as reported previously, and dissolved in 0.6M KCl•5 mM 2-mercaptoethanol 25 mM Tris-HCl buffer pH 7.4. Up to 5mM ATP was added to the solution, and the mixture was gently stirred for several minutes at 0°C. Then the mixture was centrifuged at 10, 000×g for 30 min to spin down the precipitate consisting mainly of myosin, tropomyosin, and paramyosin. The supernatant thus obtained consisted almost exclusively of actin. This actin showed a s020.w of 3.30S, and a molecular weight of about 47, 000 daltons. It was demonstrated to be composed of a single polypeptide.The intrinsic viscosity was 0.20 dl/g in the G-form and 1.6 dl/g in the F-form. This scallop actin was rich in Glu, Asp and Ala, and poor in Trp, Cys/2 and His. Except for the lower intrinsic viscosity in the F-Form, this actin is very similar to actins from various other sources.