Transient kinetic and isotopic tracer studies of the myosin adenosine triphosphatase reaction.
Transient kinetic and isotopic tracer studies of the myosin adenosine triphosphatase reaction.
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肌球蛋白腺苷三磷酸酶反应的瞬时动力学和同位素示踪研究。
DOI：
10.1002/jss.400030402
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发表时间：
1975
期刊：
影响因子：
--
通讯作者：
D. Trentham
中科院分区：
文献类型：
--
作者：
Clive R. Bagshaw;D. Trentham
通过对兔骨骼肌肌球蛋白亚段1的依赖于镁离子的三磷酸腺苷酶的瞬时动力学研究，提出了一个七步反应机制。这种机制的特点包括ATP和ADP结合的两步过程，在该过程中，除了快速的核苷酸结合步骤外，二元复合体还进行异构化。在三磷酸腺苷的情况下，一个大的负的标准自由能变化与异构化有关。在产品释放前，肌球蛋白-产物复合体的总体限速异构化已被确定。对结合到活性部位的ATP裂解机理的研究表明，这个过程很容易逆转，并可以解释产物磷酸盐中不止一个氧来自水的观察。结合的三磷酸腺苷的伽马-磷酰基的氧原子也与水进行了广泛的交换，这一发现证实了这一观点。
From transient kinetic studies of the Mg2+-dependent adenosine triphosphatase of myosin subfragment 1, prepared from rabbit skeletal muscle, a seven-step mechanism has been proposed. Features of this mechanism include two-step processes for ATP and ADP binding in which the binary complex isomerizes in addition to a rapid nucleotide association step. In the case of ATP a large negative standard free energy change is associated with the isomerization. An overall rate-limiting isomerization of the myosin-product complex prior to product release has been identified. Studies on the mechanism of cleavage of ATP bound to the active site indicate the process is readily reversible and can account for the observation that more than one oxygen of the product phosphate arises from water. This proposal has been substantiated by the finding that the oxygen atoms of the gamma-phosphoryl group of bound ATP also undergo extensive exchange with water.