THE NON-EQUIVALENCE OF BINDING-SITES OF COENZYME QUINONE AND ROTENONE IN MITOCHONDRIAL NADH-COQ REDUCTASE
THE NON-EQUIVALENCE OF BINDING-SITES OF COENZYME QUINONE AND ROTENONE IN MITOCHONDRIAL NADH-COQ REDUCTASE
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DOI：
10.1016/0014-5793(92)80862-b
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发表时间：
1992-04-06
期刊：
影响因子：
3.5
通讯作者：
KRISHNAMOORTHY, G
中科院分区：
文献类型：
--
作者：
AHMED, I;KRISHNAMOORTHY, G
荧光探针赤藓红5 '-碘乙酰胺（ER）与线粒体NADH-CoQ还原酶（复合物-I）结合，伴随荧光强度的增强。 辅酶Q类似物2，3-二甲氧基-5-甲基-6-癸基-1，4-苯醌（DB）的结合降低了ER：Complex-I体系的荧光强度。 “位点1”抑制剂鱼藤酮没有降低荧光强度，显示DB和鱼藤酮的结合位点的不同性质。 此外，DB的还原形式不增加荧光强度。 DB的荧光强度的降低被证明是由于DB的结合ER的去除。 温度跃变弛豫研究了ER结合的快速动力学。 虽然DB引起完全消除的松弛过程中的ER：复合物-I系统，鱼藤酮引起的松弛速率下降，这表明构象变化。 松弛速率显示pH依赖性，在pH 7.5附近具有最大值。
The fluorescent probe erythrosine 5'-iodoacetamide (ER) binds to mitochondrial NADH-CoQ reductase (Complex-I) accompanied by an enhancement of the fluorescence intensity. The binding of the CoQ analogue, 2,3-dimethoxy-5-methyl-6-decyl-1,4-benzoquinone (DB), decreased the fluorescence intensity of the ER:Complex-I system. The 'site 1' inhibitor rotenone did not decrease the fluorescence intensity showing the non-identical nature of the binding sites of DB and rotenone. Also, the reduced form of DB did not increase the fluorescence intensity. The decrease of the fluorescence intensity by DB was shown to be due to the removal of bound ER by DB. The rapid kinetics of ER binding was studied by temperature-jump relaxation. While DB caused complete elimination of the relaxation process in the ER:Complex-I system, rotenone caused only a decrease in the relaxation rate, suggesting conformational change. The relaxation rate showed a pH dependence with a maximum around pH 7.5.