Binding of myosin subfragment 1 to actin.
Binding of myosin subfragment 1 to actin.
复制标题
肌球蛋白亚片段 1 与肌动蛋白的结合。
DOI：
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发表时间：
1996
期刊：
影响因子：
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通讯作者：
F. Morita
中科院分区：
文献类型：
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作者：
T. Katoh;F. Morita
肌球蛋白亚片段1（S1）和层析肌动蛋白在存在和不存在的核苷酸的结合的解离常数进行了测定，在各种离子强度和各种温度。在不存在核苷酸的情况下，解离常数为nM量级，在ADP和ATP存在下，解离常数分别增加约100倍和约100，000倍。解离常数也随着离子强度的增加而增加，无论核苷酸的存在下，其对离子强度的依赖性增加的ATP的存在下，但ADP的存在下降低。S1与肌动蛋白结合的标准焓变和熵变均为正值，与核苷酸的存在无关，表明结合是熵驱动的。标准熵变基本上不受ADP的存在下，但大大降低了ATP，这表明在ATP的存在下的解离常数的大幅增加是由于疏水相互作用的减少。另一方面，在ADP的存在下，acto-S1的解离常数的增加可能是由静电相互作用的减少引起的。
The dissociation constant for the binding of myosin subfragment 1 (S1) and chromatographed actin in the presence and absence of nucleotide was measured at various ionic strengths and various temperatures. The dissociation constant was of nM order in the absence of nucleotide and increased by approximately 100- and approximately 100,000-fold in the presence of ADP and ATP, respectively. The dissociation constant also increased with increasing ionic strength, irrespective of the presence of nucleotide, and its dependence on the ionic strength was increased by the presence of ATP but decreased by the presence of ADP. The standard enthalpy change and entropy change for the binding of S1 to actin were both positive, irrespective of the presence of nucleotide, indicating that the binding was entropy-driven. The standard entropy change was essentially unaffected by the presence of ADP but was greatly decreased by ATP, suggesting that the large increase in the dissociation constant in the presence of ATP was due to the decrease of hydrophobic interactions. On the other hand, the increase in the dissociation constant for acto-S1 in the presence of ADP might be induced by the decrease of electrostatic interactions.