Stability and melting kinetics of structural domains in the myosin rod.
Stability and melting kinetics of structural domains in the myosin rod.
复制标题
肌球蛋白杆结构域的稳定性和熔化动力学。
DOI：
10.1016/0022-2836(83)90060-8
复制
发表时间：
1983
影响因子：
5.6
通讯作者：
Harrington,WF
中科院分区：
文献类型：
--
作者：
Tsong,TY;Himmelfarb,S;Harrington,WF
研究了兔肌球蛋白棒中α-螺旋构象的热稳定性和熔化动力学。溴化氰切割长肌球蛋白亚片段-2产生一个与短亚片段-2对应的螺旋状α-螺旋片段，分子量为90000 (Mr= 45000)，两个铰链区片段分子量为32000 ~ 34000 （Mr= 16000 ~ 17000）和24000 ~ 26000 （Mr= 12000 ~ 13000）。长亚片段-2及其溴化氰片段的旋光熔融实验和跳温动力学研究表明，铰链和短亚片段-2是准独立的协同单元。铰链内α-螺旋结构的热稳定性明显低于侧面的短亚片段-2和肌球蛋白棒的轻肌球蛋白区域。螺旋熔化有两个弛豫过程，一个在亚毫秒范围内（τf），另一个在毫秒范围内（τs），在杆的轻肌球蛋白和短亚片段-2区域，但在铰链区域的熔化以快速（τf）过程为主。结果表明，亚片段-2连杆的铰域可能是环形交叉桥的受力轨迹。
The thermal stability and melting kinetics of the α-helical conformation within several regions of the rabbit myosin rod have been investigated. Cyanogen bromide cleavage of long myosin subfragment-2 produced one coiled-coil α-helical fragment corresponding to short subfragment-2 with molecular weight 90,000 (Mr= 45,000) and two fragments from the hinge region with molecular weights of 32,000 to 34,000 (Mr= 16,000 to 17,000) and 24,000 to 26,000 (Mr= 12,000 to 13,000). Optical rotation melting experiments and temperature-jump kinetic studies of long subfragment-2 and its cyanogen bromide fragments show that the hinge and the short subfragment-2 domains melt as quasi-independent co-operative units. The α-helical structure within the hinge has an appreciably lower thermal stability than the flanking short subfragment-2 and light meromyosin regions of the myosin rod. Two relaxation processes for helix-melting, one in the submillisecond range (τf) and the other in the millisecond range (τs), are observed in the light meromyosin and short subfragment-2 regions of the rod, but melting in the hinge domain is dominated by the fast (τf) process. Results suggest that the hinge domain of the subfragment-2 link may be the locus of force generation in a cycling cross-bridge.