Matsubara I, Yagi N, Miura H, Ozeki M, Izumi T
Nature. 1984;312(5993):471-3. doi: 10.1038/312471a0.
According to the cross-bridge model of muscle contraction, an interaction of myosin heads with interdigitating actin filaments produces tension. Although X-ray equatorial diffraction patterns of active (contracting) muscle show that the heads are in the vicinity of the actin filaments, structural proof of actual attachment of heads to actin during contraction has been elusive. We show here that during contraction of frog skeletal muscle, the 5.9-nm layer line arising from the genetic helix of actin is intensified by as much as 56% of the change which occurs when muscle enters rigor, using a two-dimensional X-ray detector. This provides strong structural evidence that myosin heads do in fact attach during contraction.
根据肌肉收缩的横桥模型，肌球蛋白头部与交错排列的肌动蛋白丝相互作用产生张力。尽管活性（收缩）肌肉的X射线赤道衍射图表明头部靠近肌动蛋白丝，但在收缩过程中头部与肌动蛋白实际附着的结构证据一直难以获得。我们在此表明，在青蛙骨骼肌收缩过程中，使用二维X射线探测器，由肌动蛋白遗传螺旋产生的5.9纳米层线增强了多达肌肉进入僵直状态时所发生变化的56%。这提供了有力的结构证据，证明肌球蛋白头部在收缩过程中确实会附着。
