Kensler R W, Levine R J
J Cell Biol. 1982 Feb;92(2):443-51. doi: 10.1083/jcb.92.2.443.
Long, thick filaments (greater than 4.0 micrometer) rapidly and gently isolated from fresh, unstimulated Limulus muscle by an improved procedure have been examined by electron microscopy and optical diffraction. Images of negatively stained filaments appear highly periodic with a well-preserved myosin cross-bridge array. Optical diffraction patterns of the electron micrographs show a wealth of detail and are consistent with a myosin helical repeat of 43.8 nm, similar to that observed by x-ray diffraction. Analysis of the optical diffraction patterns, in conjunction with the appearance in electron micrographs of the filaments, supports a model for the filament in which the myosin cross-bridges are arranged on a four-stranded helix, with 12 cross-bridges per turn or each helix, thus giving an axial repeat every third level of cross-bridges (43.8 nm).
通过一种改进的方法从新鲜的、未受刺激的鲎肌肉中快速且轻柔地分离出的长而粗的细丝（大于4.0微米），已通过电子显微镜和光学衍射进行了检查。负染细丝的图像呈现出高度周期性，肌球蛋白横桥阵列保存完好。电子显微镜照片的光学衍射图案显示出丰富的细节，并且与43.8纳米的肌球蛋白螺旋重复一致，这与通过X射线衍射观察到的相似。结合细丝在电子显微镜照片中的外观对光学衍射图案进行分析，支持了一种细丝模型，其中肌球蛋白横桥排列在四链螺旋上，每一圈或每个螺旋有12个横桥，因此每三个横桥水平就有一个轴向重复（43.8纳米）。
