Actomyosin viscosity changes

Wu, M. C., Lanier, T. C., and Hamann, D. D. 1985a. Rigidity and viscosity changes of croacker actomyosin during thermal gelation, y. FoodSci. 50 14-19. 

When 0.1 M sodium glutamate was added to carp actomyosin, denaturation during frozen storage was almost eliminated, as measured by changes in solubility, viscosity, ultracentrifugal behavior, ATPase activity and electron microscopic profiles (66,72) (Figure 3). This protective effect of sodium glutamate will be discussed below. 

The changes in viscosity observed in solutions of muscle actomyosin on addition of ATP are explained by a dissociation of the actomyosin complex into its component parts, actin and myosin. Since thrombosthenin behaves similarly, it must be assumed that it too has dissociated into the corresponding components, which have been termed thrombosthenin A and thrombosthenin M, (A for actin-like, M for myosin-like) (Bettex-Galland et al., 1962, 1963a). 

The changes that occur in viscosity and ultracentrifugal pattern during frozen storage suggest deformation of actomyosin filaments into some denser, less asymmetric form. 

The actomyosin fraction can be freed from L-myosin by further reprecipitation. It too tends to denature on repeated precipitation and on ageing, and although the actual viscosity does not change much, the ATP sensitivity decreases at first slowly, and then more rapidly. When... 

---