Spectroscopic study of the self‐association of myosin

Homodyne and heterodyne measurements have been made of the spectrum and intensity of laser light scattered from solutions of skeletal muscle myosin at high salt concentrations. The spectral broadening and intensity measurements are consistent with the hypothesis that a myosin monomer‐dimer equilibrium exists in these solutions. Values have been calculated for molecular weight and radius of gyration of the myosin monomer, virial coefficients, and diffusion constants of both monomer and dimer, and equilibrium constant of the reaction to form dimer. Diffusion constant measurements yield an approximate length of 1481 Å for the monomer and 2121 Å for the dimer. The significance of these lengths is discussed in terms of the models of Huxley and Pepe for the structure of the myofilament.