Suda H, Sugimoto M, Chiba M, Uemura C
Department of Biological Science and Technology, Tokai University, Shizuoka, Japan.
Biochem Biophys Res Commun. 1995 Jun 6;211(1):219-25. doi: 10.1006/bbrc.1995.1799.
During muscle contraction, chemical energy from ATP hydrolysis is converted to the relative sliding movement of actin and myosin filaments. In order to elucidate the molecular mechanism of sliding-force generation, it is a crucial clue to know an elastic modulus of myosin. Here, we report direct measurements of Young's modulus of myosin head (myosin subfragment-1) isolated from rabbit skeletal muscle, using a surface forces apparatus. Our results show that the elasticity of myosin subfragment-1 has direction and is about 0.3 GPa along the long axis during ATP hydrolysis. When the bow-shaped subfragment-1 is modelled as an elastic rod, the stiffness and the bending fluctuations of subfragment-1 are calculated to be 3-7 pN/nm and about 1 nm, respectively. These results strongly support a model of multiple power strokes rather than the conventional tilting-crossbridge model.
在肌肉收缩过程中，ATP水解产生的化学能转化为肌动蛋白和肌球蛋白丝的相对滑动运动。为了阐明滑动力产生的分子机制，了解肌球蛋白的弹性模量是一个关键线索。在此，我们报告了使用表面力装置对从兔骨骼肌中分离出的肌球蛋白头部（肌球蛋白亚片段-1）的杨氏模量进行的直接测量。我们的结果表明，肌球蛋白亚片段-1的弹性具有方向性，在ATP水解过程中沿长轴约为0.3 GPa。当将弓形的亚片段-1建模为弹性杆时，计算得出亚片段-1的刚度和弯曲波动分别为3-7 pN/nm和约1 nm。这些结果有力地支持了多功率冲程模型，而不是传统的倾斜横桥模型。
