Roles for metal ions in the hydrolysis of adenosine triphosphate by the 13S coupling factors of bacterial and mitochondrial oxidative phosphorylation.
Roles for metal ions in the hydrolysis of adenosine triphosphate by the 13S coupling factors of bacterial and mitochondrial oxidative phosphorylation.
复制标题
金属离子在细菌和线粒体氧化磷酸化的 13S 偶联因子水解三磷酸腺苷中的作用。
DOI：
10.1021/bi00739a024
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发表时间：
1973
期刊：
影响因子：
2.9
通讯作者：
E. Moudrianakis
中科院分区：
文献类型：
--
作者：
R. Adolfsen;E. Moudrianakis
Robert Adolfsent和Evangelos N. Moudrianakis* 摘要：一价和二价阳离子均能增强粪产碱菌氧化磷酸化13 S偶联因子的ATP酶活性。通过Mg 2+的活化涉及形成容易可逆的金属-酶复合物，而不是形成Mg-ATP。当一价阳离子存在于反应混合物中时，可以刺激酶的二价阳离子的种类受到更多限制。例如，在不存在K+的情况下，Ca 2+的活化效果与Mg 2+一样好，但在存在K+的情况下完全没有效果。金属离子激活的幅度随ATP浓度而变化。随着ATP浓度的增加，K+的活化程度降低，而Mg 2+的活化程度增加。在低ATP浓度下，K+比Mg ~（2+）激活更强。单独用K+或Mg ~（2+）增强酶的活性，既增加了催化常数，也增加了产物的释放速率，或两者都增加，而不改变酶对ATP的亲和力。然而，行动N的机制。本实验室最近的工作是阐明腺嘌呤核苷酸与氧化磷酸化和光合磷酸化的~（13）S偶联因子之间发生的反应，特别是酶-核苷酸复合物中发生的转化。对结合过程和偶联因子结合核苷酸的相互转化的理解将有助于更好地理解ATP合成中涉及的化学步骤。从菠菜叶绿体中分离的同质13 S偶联因子CFi * 1** 可结合2 mol ADP，并通过转磷酸化反应将其中一些转化为AMP和ATP（Roy和Moudrianakis，1971）。关于来自革兰氏阴性菌粪产碱菌的氧化磷酸化的13 S不耐热偶联因子（HLF），也报告了类似的发现（Adolfsen和Moudrianakis，1973）。这些结果的一个可能的解释是，该反应代表了氧化磷酸化和光合磷酸化中ATP合成的最终步骤。
Robert Adolfsent and Evangelos N. Moudrianakis* abstract: The ATPase activity of the 13S coupling factor of oxidative phosphorylation from Alcaligenes faecalis was en-hanced by both monovalent and divalent cations. Activation by Mg2+ involves formation of a readily reversible metal-enzyme complex and not the formation of Mg-ATP. The variety of divalent cations that could stimulate the enzyme was much more restricted when monovalent cations were present in the reaction mixture. For example, Ca2+ activated just as well as Mg2+ in the absence of K+ but had no effect at all in the presence of K+. The magnitude of metal ion activation varied with ATP concentration. The extent of K+ activation decreased with increasing ATP concentration, while that of Mg2+ increased with increasing ATP concentration. At low ATP concentration K+ activated much more strongly than Mg2+. The enhancement of activity by either K+ or Mg2+ alone involves an increase in eitherthe catalytic constant or the rate of release of products or both, without alteration of the affinity of the enzyme for ATP. However, the mechanisms of action n. L Vecent efforts of this laboratory have been directed to-ward the elucidation of the reactions occurring between adenine nucleotides and the 13S coupling factors of oxidative and photosyntheticphosphorylation and especially the trans-formations occurring within the enzyme-nucleotide complex. An understanding of the binding process and the intercon-versions of coupling factor-bound nucleotides should lead to a better understanding of the chemical steps involved in the synthesis of ATP. The homogeneous 13S coupling factor isolated from spinach chloroplasts, CFi,* 1** binds 2 mol of ADP and converts some of it into AMP and ATP by means of a transphosphorylation reaction (Roy and Moudrianakis, 1971). Similar findings have been reported concerning the 13S, heat-labile coupling factor (HLF) of oxidative phosphorylation from the Gram-negative bacterium Alcaligenes faecalis (Adolfsen and Moudrianakis, 1973). One possible explanation of these results is that the reaction represents the terminal step in the synthesis of ATP in both oxidative and photo-synthetic phosphorylation.