Modification of bovine heart succinate dehydrogenase with ethoxyformic anhydride and rose bengal: evidence for essential histidyl residues protectable by substrates.
Modification of bovine heart succinate dehydrogenase with ethoxyformic anhydride and rose bengal: evidence for essential histidyl residues protectable by substrates.
复制标题
用乙氧基甲酸酐和玫瑰红对牛心琥珀酸脱氢酶进行修饰：底物保护必需组氨酰残基的证据。
DOI：
10.1016/0003-9861(86)90593-x
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发表时间：
1986
影响因子：
3.9
通讯作者：
Hatefi,Y
中科院分区：
文献类型：
--
作者：
Hederstedt,L;Hatefi,Y
在光存在下，来自牛心脏线粒体的纯化膜结合琥珀酸脱氢酶 (SDH) 被组氨酸修饰试剂乙氧基甲酸酐 (EFA) 和玫瑰红抑制。琥珀酸和竞争性抑制剂可防止抑制，并减少 EFA 修饰的组氨酰残基数量。 EFA修饰的必需残基不是SDH的必需硫醇，但必需硫醇的修饰消除了丙二酸对EFA抑制SDH的保护作用。当抑制≤35%时，羟胺几乎完全逆转EFA抑制，而当抑制更广泛时，羟胺仅部分逆转。羟胺处理前后 EFA 修饰的 SDH 的紫外光谱表明，EFA 对 SDH 的广泛抑制可能导致组氨酰残基的两个咪唑氮上发生乙氧基甲酰化。这种修饰不能被羟胺逆转。几种不同来源的琥珀酸脱氢酶和富马酸还原酶具有相似的组成，并且来自大肠杆菌的两种酶在其各自的黄素蛋白和铁硫蛋白亚基的氨基酸组成方面具有相当大的同源性。前者有一小段含有保守的组氨酸、半胱氨酸和精氨酸残基。这些残基，如果在牛酶中也保守的话，可能是本研究（组氨酸）和之前的（半胱氨酸、精氨酸）所建议的重要活性位点残基。
Purified and membrane-bound succinate dehydrogenase (SDH) from bovine heart mitochondria was inhibited by the histidine-modifying reagents ethoxyformic anhydride (EFA) and Rose Bengal in the presence of light. Succinate and competitive inhibitors protected against inhibition, and decreased the number of histidyl residues modified by EFA. The essential residue modified by EFA was not the essential thiol of SDH, but modification of the essential thiol abolished the protective effect of malonate against inhibition of SDH by EFA. The EFA inhibition was reversed by hydroxylamine nearly completely when the inhibition was ⩽35%, and only partially when the inhibition was more extensive. The uv spectrum of EFA-modified SDH before and after hydroxylamine treatment suggested that extensive inhibition of SDH with EFA may result in ethoxyformylation at both imidazole nitrogens of histidyl residues. Such a modification is not reversed by hydroxylamine. Succinate dehydrogenases and fumarate reductases from several different sources have similar compositions, and the two enzymes fromEscherichia colihave considerable homology in the amino acid composition of their respective flavoprotein and iron-sulfur protein subunits. In the former, there is a short stretch containing conserved histidine, cysteine, and arginine residues. These residues, if also conserved in the bovine enzyme, may be the essential active site residues suggested by this work (histidine) and previously (cysteine, arginine).