ANALYSIS OF SOME THERMODYNAMIC PROPERTIES OF IRON-SULFUR CENTERS IN SITE-I OF MITOCHONDRIA
ANALYSIS OF SOME THERMODYNAMIC PROPERTIES OF IRON-SULFUR CENTERS IN SITE-I OF MITOCHONDRIA
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DOI：
10.1042/bj1860111
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发表时间：
1980-01-01
影响因子：
4.1
通讯作者：
OHNISHI, T
中科院分区：
文献类型：
--
作者：
INGLEDEW, WJ;OHNISHI, T
用氧化还原电位法测定了不同pH值下鸽、牛心线粒体I位不同Fe-S中心的中点电位。一个有趣的特征是中心N-2的pH依赖性，它是呼吸链NADH脱氢酶片段的最高潜在成分。用琥珀酸/富马酸对测定了中心N-2(NADH脱氢酶)和S-1(琥珀酸脱氢酶)的表观中点电位及其与pH的关系。同样，中心N-2在中点电位上是pH依赖的，而中心S-1不是。用琥珀酸/富马酸对滴定的结果与氧化还原电位法的结果是一致的。在鱼藤酮存在下，以NADH/NAD+和类似物(还原/氧化)为中心的Fe-S中心的氧化还原滴定结果与氧化还原电位法的结果有很大不同，这些差异可能是由于NADH脱氢酶的作用机制及其与NADH的特异性相互作用所致。在NAD+/NADH平衡体系中加入ATP会导致中心N-4的非偶联剂敏感的氧化。
The midpoint potentials of the various Fe-S centers in Site I [from pigeon and ox heart mitochondria] were determined at different pH values by the technique of redox potentiometry. An interesting feature is the pH-dependence of Center N-2, the highest potential component of the NADH dehydrogenase segment of the respiratory chain. The apparent midpoint potentials of Center N-2 (NADH dehydrogenase) and S-1 (succinate dehydrogenase) and their pH-dependence was also determined by using the succinate/fumarate couple. Again Center N-2 is pH-dependent in midpoint potential, and Center S-1 is not. The results obtained by titrating with the succinate/fumarate couple are in quantitative agreement with those obtained for these centers by redox potentiometry. Oxidation-reduction titrations of Fe-S centers with the couple NADH/NAD+ and an analog acetylpyridine-adenine nucleotide (reduced/oxidized) in the presence of rotenone gave results substantially different from those obtained by redox potentiometry; these differences may be due to the mechanism of action of NADH dehydrogenase and its specific interaction with NADH. The addition of ATP to an NAD+/NADH-poised system induces an uncoupler-sensitive oxidation of Center N-4.