Freeze Denaturation of Squid Actomyosin

Denaturation of actomyosin from the obliquely striated mantle muscle of squids (Todarodes pacificus) was studied by measuring the changes in -ATPase activity, relative viscosity, and solubility during frozen storage at three different temperature zones of maximum ice crystal formation , the eutectic point , and . The logarithms of -ATPase activity, relative viscosity and solubility of the actomyosin solutions (0.6 M KCl) and suspensions (0.05 M KCl) tended to decrease during frozen storage. The denaturation of squid actomyosin at the zone of maximum ice crystal formation significantly differed by only two degree of temperature difference between and , and it (0.05 M KCl) at was less than those of other temperature. The denaturation at was more rapid than at . The logarithms of -ATPase activity, relative viscosity, and solubility were changed slower in the suspensions (0.05 M KCl) than the solutions (0.6 M KCl) at all experimental temperatures.