Dept. of Biochemistry and Molecular Biology, Ferrara University, Via Borsari 46, 44121 Ferrara, Italy.
Arch Biochem Biophys. 2013 May;533(1-2):42-6. doi: 10.1016/j.abb.2013.02.016. Epub 2013 Mar 6.
The anisotropy decay of the spin-labelled myosin subfragment-1, takes place with different rates depending on the physiological state of muscle: relaxation, isometric contraction and rigor. The decay is mostly explained by the rotation of myosin subfragment-1. This rotation is promoted by thermal energy and is opposed by the viscous and by the elastic reactions. A model is proposed that relates the amplitude of the rotation of myosin subfragment-1 to its stiffness. It is found that the amplitude of the rotation is inversely proportional to the stiffness assigned to the structure. It is concluded that, in relaxed myofibrils, the stiffness of myosin subfragment-1 is much lower than that in myosin subfragment-1 - F-actin. The consequences of this finding on modeling of muscle contraction are discussed.
肌球蛋白小片段-1 的各向异性衰减，根据肌肉的生理状态（松弛、等长收缩和僵硬）以不同的速率发生。衰减主要归因于肌球蛋白小片段-1 的旋转。这种旋转是由热能推动的，而粘性和弹性反应则对其起阻碍作用。本文提出了一个与肌球蛋白小片段-1 旋转幅度相关的模型，该模型与结构的刚性有关。研究发现，旋转幅度与赋予该结构的刚性成反比。因此可以得出结论，在松弛的肌原纤维中，肌球蛋白小片段-1 的刚性远低于肌球蛋白小片段-1-F-肌动蛋白。该研究结果对肌肉收缩建模的影响将在文中进行讨论。
