STUDIES OF 8-AZIDO-ATP ADDUCTS REVEAL 2 MECHANISMS BY WHICH ATP BINDING TO CYTOCHROME-C COULD INHIBIT RESPIRATION
STUDIES OF 8-AZIDO-ATP ADDUCTS REVEAL 2 MECHANISMS BY WHICH ATP BINDING TO CYTOCHROME-C COULD INHIBIT RESPIRATION
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DOI：
10.1021/bi00008a036
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发表时间：
1995-02-28
期刊：
影响因子：
2.9
通讯作者：
WALLACE, CJA
中科院分区：
文献类型：
--
作者：
CRAIG, DB;WALLACE, CJA
我们已经提出，在一个亲和力和特异性很强的位置结合ATP可以调节细胞色素c与其生理伙伴的活性，从而调节线粒体电子传递的整体效率。我们现在描述使用ATP亲和标记蛋白来测试该位点的占用，包括不变的精氨酸91，对纯化的细胞色素c还原酶和氧化酶的细胞色素c活性的影响以及它与线粒体内膜的联系。还原酶和氧化物酶的电子转移活性分别被抑制到原值的41%和11%-15%。区分与两个主要生理配对的反应的活性抑制程度的显著差异足以在整个线粒体中引起明显的转变，从从还原酶到细胞色素c的限速转移，到细胞色素c和两个氧化还原配对之间的转移速率更均匀地匹配的状态。部位占有率也大大降低了细胞色素c从膜上半最大解离所需的离子强度。这些数据表明，ATP结合引起的电子传递效率的降低可以归因于蛋白质与单个生理伙伴的活性的降低，可能与其与线粒体内膜的亲和力的降低有关，并表明ATP对细胞呼吸的反馈调节也是以类似的方式进行的。
We have proposed that the binding of ATP at a site of substantial affinity and specificity could regulate the activity of cytochrome c with its physiological partners and thus the overall efficiency of mitochondrial electron transport. We now describe the use of ATP affinity-labeled protein to test the effect of occupancy of that site, which includes the invariant arginine 91, on the activity of cytochrome c with purified cytochrome c reductase and oxidase and its association with the mitochondrial inner membrane. Electron-transfer activities with the reductase and oxidase were inhibited by site occupancy to 41% and 11-15% of native values, respectively. The marked difference in the degree of inhibition of activity that distinguishes the reactions with the two major physiological partners was sufficient to cause, in whole mitochondria, a demonstrable shift from a situation in which there is a rate-limiting transfer from the reductase to cytochrome c, to a state where rates are more evenly matched for transfers between cytochrome c and the two redox partners. Site occupancy also substantially reduces the ionic strength necessary for half-maximal dissociation of cytochrome c from the membrane. These data imply that the decreased efficiency of electron transfer caused by ATP attachment can be attributed to a decrease in the protein's activity with individual physiological partners, possibly compounded with a decrease in its affinity for the inner mitochondrial membrane, and suggest that feedback regulation by ATP of cellular respiration operates in like manner.