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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Rapid hydrolysis of ATP by mitochondrial F-1-ATPase correlates with the filling of the second of three catalytic sites
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Rapid hydrolysis of ATP by mitochondrial F-1-ATPase correlates with the filling of the second of three catalytic sites

机译：线粒体F-1-ATPase对ATP的快速水解与三个催化位点中第二个的填充有关

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摘要

Strong positive catalytic cooperativity is a central feature of the binding change mechanism for F-1-ATPases. However, a detail of the mechanism that remains controversial is whether the kinetic enhancement derived from using substrate-binding energy at one catalytic site to promote product release from another site occurs upon the filling of the second or third of three catalytic sites on F-1. To address this question, we compare the ATP concentration dependence of the rate of ATIP hydrolysis by F, from beef heart mitochondria to the ATIP concentration dependence of the level of occupancy of catalytic sites during steady-state catalysis as measured by a centrifuge filtration assay. A single K-m(ATP) is observed at 77 +/- 6 mu M. Analysis of the nucleotide-binding data shows that half-maximal occupancy of a second catalytic site occurs at 78 18 mu M ATP. We conclude that ATP binding to a second catalytic site is sufficient to support rapid rates of catalysis.
机译：强烈的正催化协同作用是F-1-ATPase结合改变机制的主要特征。然而，仍然有争议的机制的一个细节是，在F-1上三个催化位点的第二个或第三个被填充时，是否发生了在一个催化位点使用底物结合能促进产物从另一位释放的动力学增强作用。 。为了解决这个问题，我们比较了从牛肉心线粒体经F的ATIP水解速率对ATP浓度的依赖性与在稳态催化过程中通过离心过滤测定法测量的催化位点占用水平的ATIP浓度依赖性。在77 +/- 6μM处观察到一个K-m（ATP）。对核苷酸结合数据的分析表明，第二个催化位点的最大占用量出现在78 18μM ATP处。我们得出结论，ATP与第二个催化位点的结合足以支持快速的催化速率。

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