Involvement of a histidine residue in the interaction between membrane-anchoring protein (QPs) and succinate dehydrogenase in mitochondrial succinate-ubiquinone reductase.
Involvement of a histidine residue in the interaction between membrane-anchoring protein (QPs) and succinate dehydrogenase in mitochondrial succinate-ubiquinone reductase.
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组氨酸残基参与膜锚定蛋白（QP）和线粒体琥珀酸泛醌还原酶中琥珀酸脱氢酶之间的相互作用。
DOI：
10.1016/s0005-2728(05)80282-8
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发表时间：
1991
期刊：
影响因子：
--
通讯作者：
Yu,CA
中科院分区：
文献类型：
--
作者：
Paudel,HK;Yu,L;Yu,CA
利用组氨酸修饰试剂二乙基焦碳酸酯（DEPC）研究了膜锚定蛋白（QPs）部分组氨酸残基参与琥珀酸脱氢酶重构生成琥珀酸泛醌还原酶的过程。当QPs在50 mM Tris-HCl （pH 7.0）中用1 mM DEPC在0°C下处理30分钟时，最大失活率为80%。DEPC还使85%的完整琥珀酸泛醌还原酶失活。DEPC对琥珀酸-泛醌还原酶的失活是琥珀酸脱氢酶必需组氨酸残基修饰的结果。失活不是由于QPs中组氨酸残基的修饰，而组氨酸残基是与琥珀酸脱氢酶相互作用所必需的，因为从失活的琥珀酸泛醌还原酶解离的QPs在与活性琥珀酸脱氢酶的重构中具有活性。显然，QPs中的必需组氨酸受到琥珀酸脱氢酶的屏蔽，因此无法在琥珀酸泛素还原酶中进行DEPC修饰。QPs的组氨酸残基参与琥珀酸脱氢酶的相互作用，在depc失活的琥珀酸泛素还原酶的还原细胞色素-560 α-吸收峰上存在553 nm肩带（QPs与琥珀酸脱氢酶物理关联的特征）进一步证明。当琥珀酸脱氢酶和depc处理的QPs的混合物与二亚砜还原时，该肩消失。在depc处理的样品中，每个QPs分子中大约有一个组氨酸残基被修饰，这表明只有一个组氨酸残基是与琥珀酸脱氢酶相互作用所必需的。这个必需组氨酸组位于QPs的较小亚基（mr13000）上。
The involvement of a histidine residue of the membrane-anchoring protein (QPs) fraction in reconstitution of succinate dehydrogenase to form succinate-ubiquinone reductase is studied by using a histidine-modifying reagent, diethylpyrocarbonate (DEPC). A maximum inactivation of 80% of reconstitutive activity is obtained when QPs is treated with 1 mM DEPC at 0°C for 30 min in 50 mM Tris-HCl (pH 7.0). DEPC also inactivates about 85% of intact succinate-ubiquinone reductase. The inactivation of succinate-ubiquinone reductase by DEPC is a result of the modification of essential histidine residues of succinate dehydrogenase. The inactivation is not a result of the modification of the histidine residue in QPs which is essential for interaction with succinate dehyrogenase because the QPs dissociated from the inactivated succinate-ubiquinone reductase is active in reconstitution with active succinate-dehydrogenase. Apparently, the essential histidine in QPs is shielded by succinate dehydrogenase and thus inaccessible to DEPC modification in succinate-ubiquinone reductase. The involvement of a histidine residue of QPs in interaction with succinate dehydrogenase is further evident by the presence of 553 nm shoulder on the α-absorption peak of reduced cytochromeb-560 (a characteristic of physical association of QPs with succinate dehydrogenase) in the DEPC-inactivated succinate-ubiquinone reductase. This shoulder disappears from a mixture of succinate dehydrogenase and DEPC-treated QPs when reduced with dithionite. About one histidine residue per molecule of QPs is modified in the DEPC-treated sample, suggesting that only one histidine residue is essential for interaction with succinate dehyrogenase. This essential histidine group is located in the smaller subunit (Mr13 000) of QPs.