コイミオシンの熱変性に対する糖の保護効果
1984 年 50 巻 3 号 p. 521-529
詳細
1984 年 50 巻 3 号 p. 521-529
When carp myosin was kept at 27°C or 30°C in the presence of various concentreations of sorbitol or lactitol, myosin Ca-and EDTA-ATPases were inactivted in a single first order rate (kD) process whereas the inactivation of actin-activated myosin Mg-ATPase proceeded in two steps: an early fast decrease (kDf), followed by a slow decrease (kDs). The increase in the turbidity of myosin suspension also occurred in two steps with similar rates (k1 and k2) to those for inactivation of activacted myosin Mg-ATPase.
Plotting the logarithm of rate constant against the molarity of sugar, the linear relations were obtained for all indices employed. A slope of the graph of the logarithm of rate constant versus the molarity of sugar expressd the protective effect (E) of sugar against thermal denaturation of carp myosin.
Judged from the E values, it was strongly suggested that the presence of sugar during the heat-treatment effectively protected the denaturation of an enzymatic site of myosin molecule compared with that of thick filaments (self-assembly) of the same molecule. In addition, the effect of lactitol was nearly two-fold stronger than that of sorbitol for the denaturation of all biochemical properties studied.
