扇贝肌球蛋白调节性轻链解离的机制。
The mechanism of regulatory light chain dissociation from scallop myosin.
作者信息
Bennett A J, Bagshaw C R
出版信息
Biochem J. 1986 Jan 1;233(1):179-86. doi: 10.1042/bj2330179.
The dissociation of the regulatory light chains from scallop myosin subfragments, on addition of EDTA, was investigated by using the fluorophore 8-anilinonaphthalene-1-sulphonate as a probe. The rate of this process (0.014 s-1) was partially limited by the rate of Mg2+ dissociation (0.058 s-1) from the non-specific high-affinity site. The dissociation of the regulatory light chain subfragment 1 was less extensive than from heavy meromyosin. Reassociation of the scallop regulatory light chain was induced on addition of Mg2+, but it appeared to be limited by a first-order step. The nature of this step was revealed by the kinetics of Mercenaria regulatory light chain association. Scallop heavy meromyosin, denuded of its regulatory light chains, exists in a refractory state, whose reversal to the nascent state limits the rate of light chain association (0.006 s-1). The formation of the refractory state is the driving force for the net dissociation of regulatory light chains from scallop heavy meromyosin. This mechanism is discussed with reference to existing structural information on light-chain-denuded myosin.
通过使用荧光团8-苯胺基萘-1-磺酸盐作为探针，研究了添加乙二胺四乙酸（EDTA）后扇贝肌球蛋白亚片段中调节轻链的解离情况。该过程的速率（0.014 s⁻¹）部分受Mg²⁺从非特异性高亲和力位点解离速率（0.058 s⁻¹）的限制。调节轻链亚片段1的解离程度比重酶解肌球蛋白的解离程度小。添加Mg²⁺后诱导了扇贝调节轻链的重新结合，但这似乎受一级步骤的限制。该步骤的性质通过美西螈调节轻链结合的动力学得以揭示。去除调节轻链的扇贝重酶解肌球蛋白处于一种难恢复状态，其向新生状态的逆转限制了轻链结合的速率（0.006 s⁻¹）。难恢复状态的形成是调节轻链从扇贝重酶解肌球蛋白净解离的驱动力。结合关于去除轻链的肌球蛋白的现有结构信息对该机制进行了讨论。
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