Hydrodynamic studies on the self association of vertebrate skeletal muscle myosin.

Sedimentation velocity studies on myosin A solutions at high ionic strength combined with computer-simulation of the concentration dependence of the sedimentation coefficient for a rapidly reversible monomer-dimer equilibrium have confirmed that if such an equilibrium does exist it has an equilibrium constant of less than 10 ml/g. A new hydrodynamic treatment has been used to calculate the molecular weight of myosin from s0 and ks alone and has yielded a value of 470 000. Combination of viscosity and sedimentation velocity results has shown that the myosin molecule displays little swelling (Vs/v = 1.1 +/- 0.1). A new picture of the myosin molecule is presented in which a conformational change in the head region is suggested to account for the variation in published s 0 values.