Comparison of molecular weight of myosin from normal and failing dog hearts

¹ Department of Medical Research, Veterans Administration Hospital, and Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio

The molecular weight of myosin from dog hearts was determined with the analytic ultracentrifuge and by light scattering. Both normal dog hearts and hearts with surgically induced left ventricular failure were used The molecular length was calculated from the light-scattering data. The molecular weight of normal myosin was 554,000 from ultracentrifugation and 512,000 by light scattering. For myosin from failing left ventricles the molecular weight was 502,000 by ultracentrifugation and 510,000 by light scattering. The molecular lengths calculated for a rod model were 1,750 A for myosin from normal hearts and 2,000 A for that from failing left ventricles. The molecular weight and length determined by this work for myosin from failing hearts do not differ significantly from the molecular weight and length of myosin from normal hearts (P > .1).

Key Words: molecular length • experimental mitral insufficiency • left ventricle-body weight index • failing left ventricles • ultracentrifugation • Archibald method for determination of molecular weights • light scattering • refractive increment • extinction coefficient

Submitted on May 4, 1964