Heat-induced Gelation of Myosin Filaments at a Low Salt Concentration

The heat-induced gelation properties of myosin in low salt concentration were studied. Freshly prepared myosin formed gels with an extremely high rigidity in 0.1 to 0.3 m KC1 at pH 6.0 on heating. This high heat-induced gel formability of myosin filaments diminished during storage, concomitant with the loss of the filament formability inherent in the native myosin. Presumably intermolecular aggregation was the cause of this loss during storage. The difference in the heat-induced gelation of myosin filaments at a low salt concentration (0.2 m KC1) and that of myosin monomers at a high salt concentration (0.6 m KC1) was clearly.distinguishable from their gelling behavior. The high gelation ability of freshly prepared myosin filaments upon heating seems to develop through the interfilamental head-head aggregation on the surface of the filaments without involving the tail portion of the molecule.