高濃度の塩存在下におけるコイのミオシンBの変性機構
1984 年 50 巻 4 号 p. 635-643
詳細
1984 年 50 巻 4 号 p. 635-643
The denaturation mechanism of carp myosin B with high concentration of NaCl has been studied by measuring the changes in its biochemical properties.
During the time carp myosin B was kept at 10°C in the presence of 2.0M NaCl (at pH 7.0), a decrease in Mg-ATPase activity, a decline in viscosity as well as in its ATP sensitivity, an increase in EDTA-ATPasp activity, change in the thermal inactivation mode of Ca-ATPase from a single first order process to biphasic first order behaviour, and a release in a large quantity of actin were found to occur, while Ca-ATPase remained at the same activity level.
By salting out with (NH4)2SO4 in the presence of 5 mM ATP-Mg, myosin was isolated from the NaCl-treated myosin B. The Ca- and EDTA-ATPase activities, actin-activated Mg-ATPase activity and actin-binding ability of this myosin were identical with those of myosin from untreated myosin B. The NaCl-induced changes in the biochemical properties of carp myosin B, Bove mentioned, were fully restored by the addition of F-actin. These results revealed that a considerable portion of F-actin in the myosin B was denatured faster than its myosin portion during the reaction with high concentration of salt.
