The effect of concentrated salt solution on the freeze denaturation of carp myosin B was investigated in connection with the length of time taken to freeze to -20°C (freezing time). The apparent rate constants for the inactivation of Ca-ATPase (k_f) were calculated on the basis of a -20°C-frozen-storage experiment with various combinations of freezing times and KCl concentra-tions. The slowly frozen sample resulted in a considerable decrease in Ca-, Mg- and EDTA-ATPase activities, and ATP-sensitivity of myosin B. The log k_f values were correlated in a definite range with the length of time from the freezing point to the end of the eutectic plateau. A high initial KCl concentration of myosin B solution before freezing and a long freezing time resulted in a large k_f value.
These findings show that the remaining activity is affected by the concentration of unforzen KCl solution and by the length of time of exposure to the concentrated solution.