抄録
Myosin rod fragments were prepared from both chicken leg and breast muscles to examine the reason for differences in the heat-induced gel strengths of these myosins at high ionic strength and low pH. The heat-induced gelation of the myosin rods was studied under the same conditions as those of intact myosin [Morita et al., Agric. Biol. Chem., 51, 2895 (1987)]. It was verified that unheated myosin rods showed similar differences in turbidity, viscosity, and filament length as intact myosin, and the heat-induced gel structures were compared. In summary, the results showed that the turbidity of breast myosin rods began to increase at pH 5.8 but that observed with leg myosin rods did not increase at that pH, although it was higher than that of breast myosin rods below pH 5.5. The viscosity of breast myosin rods increased as the pH decreased between pH 5.5 and pH 5.8, although that of leg rods decreased. At pH 5.7, leg and breast myosin rods assembled to form short filaments before heating. Both myosin rods formed longer filaments at pH 5.4, although breast rods tended to form longer ones. These results were approximately in agreement with those of intact myosin. Examination of the structure of the heat-induced gel of the leg myosin rods at pH 5.4 with scanning electron microscopy revealed a finer network structure (gel strength 3, 300 dyn/cm2) than that of breast myosin rods (2, 500 dyn/cm2) which were coarser and more aggregated than the former. These results indicate that the differences in filamentogenesis and heat-induced gelation of myosin rods from chicken leg and breast muscle myosins at high ionic strength and low pH may be related to those in thermogelation of each myosin.
