Ishiwata S, Muramatsu K, Higuchi H
Biophys J. 1985 Mar;47(3):257-66. doi: 10.1016/S0006-3495(85)83915-1.
We show in this paper that the change of the internal structure of a sarcomere in a rabbit glycerinated psoas muscle fiber can be examined by analyzing the intensity change of the first- and the second-order optical diffraction lines. A unit-cell (sarcomere)-structure model has been applied to the estimation of the length of thick filaments in a muscle fiber while they undergo dissociation. The optical factors, except for the unit-cell-structure factor, hardly changed during the dissociation of the filaments. Our results show that thick filaments dissociate from both ends on increasing the KCl concentration in the presence of 10 mM pyrophosphate and 5 mM MgCl2. Micromolar concentrations of Ca2+ suppressed to some extent the dissociation of thick filaments. The disassembly of thick filaments occurred at higher KCl concentrations in the absence of pyrophosphate. There was a correlation between the stability of the thick filament structure and cross-bridge formation, which was induced either by the addition of micromolar concentrations of Ca2+ in the presence of Mg-pyrophosphate or by removal of Mg-pyrophosphate.
我们在本文中表明，通过分析一级和二级光学衍射线的强度变化，可以检测兔甘油化腰大肌纤维中肌节内部结构的变化。一个单位细胞（肌节）结构模型已被用于估计肌纤维中粗肌丝在解离过程中的长度。在细丝解离过程中，除单位细胞结构因子外，光学因素几乎没有变化。我们的结果表明，在存在10 mM焦磷酸和5 mM氯化镁的情况下，增加氯化钾浓度时，粗肌丝从两端解离。微摩尔浓度的钙离子在一定程度上抑制了粗肌丝的解离。在没有焦磷酸的情况下，粗肌丝的拆卸发生在较高的氯化钾浓度下。粗肌丝结构的稳定性与横桥形成之间存在相关性，横桥形成是由在焦磷酸镁存在下添加微摩尔浓度的钙离子或去除焦磷酸镁诱导的。
