Quasi-elastic light scattering studies of rabbit skeletal myosin solutions

Homodyne measurements of the laser light spectrum scattered from solutions of rabbit skeletal muscle myosin in high ionic-strength media manifested a characteristic D value dependence on myosin concentrations. Using the typical D versus myosin concentration curves obtained in the presence of 0.5 M phosphate and 0.2 M phosphate respectively as references, it has been shown that: (1) the observed phenomena are completely reversible; (2) minor components such as C- and F-protein do not significantly influence the measured D values; and (3) the effect of preparation procedures on these dynamic light-scattering measurements is negligible. A common argument (irreversible aggregation) against a monomer-dimer equilibrium is ruled out; on the other hand, some doubt still remains with regard to the existence and physiological significance of a reversible dimerization.