Viscosity Changes in Carp Actomyosin Solutions

The flow property and ATPase activity were determined to clarify the behavior of carp actomyosin solution during incubation at 40° C. At higher concentration, intermolecular interaction and aggregation between actomyosin molecules occurred greatly and continued for a long time. These changes did not take place at low concentration or in actomyosin preparations containing Na 4 P 2 0 7 and MgCI 2 , which are known to dissociate actomyosin to myosin and F‐actin. These differences would be due to the difficulty of intermolecular interaction at low concentration or between smaller components. The formation of network structure during incubation was suggested from the stress relaxation behavior at a constant shear rate and the presumption of yield stress. In actomyosin solutions containing Na 2 P 2 O 7 and MgCI 2 , network structure formation during incubation was suppressed. Namely, after the incubation, both immediate stress relaxation and yield stress were much smaller than those of the solution without additives. Contrary to the observations on rabbit actomyosin, the viscosity of carp actomyosin solution increased once and then decreased. When the maximum viscosity was observed, ATPase activity decreased only by 33% of the original activity. Then, ATPase activity continued to decrease and disappeared after 180 min. In carp actomyosin solution containing Na 2 P 2 O 7 , and MgCl 2 , the viscosity change was not found, and ATPase activity remained at a definite value even after 180 min. Relationship between viscosity change and ATPase inactivation was discussed.