Phillips G N, Chacko S
Department of Biochemistry and Cell Biology, Rice University, Houston, TX 77005-1892, USA.
Biopolymers. 1996 Jan;38(1):89-95. doi: 10.1002/(SICI)1097-0282(199601)38:1%3C89::AID-BIP7%3E3.0.CO;2-S.
Tropomyosin is a protein that controls the interactions of actin and myosin as a part of the regulation of muscle contraction. The 420 A long alpha-helical coiled-coil molecules form long filaments, both in muscle and in crystals. The x-ray diffraction data from tropomyosin crystals have indicated large scale motions of the filaments that can be related to the inherent mechanical properties of the molecule, and by extension, to the role of tropomyosin in the cooperative activation of the thin filaments of muscle. Diffuse scattering analysis has provided information about the amplitudes of the motions that has been used to calculate the intrinsic flexibility of the molecule. It can then be shown that each tropomyosin molecule by itself can only mediate interactions of the nearest-neighboring tropomyosin molecules along the filament. The repeating nature of the thin filament, however, allows the entire filament to activate cooperatively.
原肌球蛋白是一种蛋白质，作为肌肉收缩调节的一部分，它控制肌动蛋白和肌球蛋白之间的相互作用。在肌肉和晶体中，420埃长的α-螺旋卷曲螺旋分子形成长丝。来自原肌球蛋白晶体的X射线衍射数据表明，这些长丝存在大规模运动，这可能与分子的固有机械性能有关，进而与原肌球蛋白在肌肉细肌丝协同激活中的作用有关。漫散射分析提供了有关运动幅度的信息，这些信息已被用于计算分子的固有柔韧性。然后可以证明，每个原肌球蛋白分子本身只能介导沿细丝与最邻近的原肌球蛋白分子的相互作用。然而，细肌丝的重复性质允许整个细丝协同激活。
