Geeves M A, Webb M R, Midelfort C F, Trentham D R
Biochemistry. 1980 Oct 14;19(21):4748-54. doi: 10.1021/bi00562a005.
During the hydrolysis of MgATP catalyzed by myosin, ATP bound to the protein undergoes a reaction such that the beta-nonbridge oxygen atoms exchange position with the beta gamma-bridge oxygen atom. The extent of this exchange was variable but averaged 45% for ATP that had been bound for 2 s at the myosin subfragment 1 active site at ionic strength 0.08 M, pH 8.0, and 22 degrees C. This result proves that ATP cleavage in the myosin active site is readily reversible. The result also suggests that the beta-phosphate of ADP that must be formed in this cleavage step is highly constrained in the protein.
在肌球蛋白催化MgATP水解的过程中，与该蛋白质结合的ATP会发生反应，使得β非桥连氧原子与βγ桥连氧原子交换位置。这种交换的程度是可变的，但对于在离子强度0.08M、pH8.0和22℃条件下已在肌球蛋白亚片段1活性位点结合2秒的ATP而言，平均交换率为45%。这一结果证明，肌球蛋白活性位点处的ATP裂解很容易逆转。该结果还表明，在此裂解步骤中必须形成的ADP的β磷酸基团在蛋白质中受到高度限制。
