A CU(I)-SEMIQUINONE STATE IN SUBSTRATE-REDUCED AMINE OXIDASES
A CU(I)-SEMIQUINONE STATE IN SUBSTRATE-REDUCED AMINE OXIDASES
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DOI：
10.1038/349262a0
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发表时间：
1991-01-17
期刊：
影响因子：
64.8
通讯作者：
KNOWLES, PF
中科院分区：
文献类型：
--
作者：
DOOLEY, DM;MCGUIRL, MA;KNOWLES, PF
铜在含铜胺氧化酶中的作用长期以来一直是争论和不确定性的来源。 许多电子顺磁共振（EPR）实验2-6，包括快速冷冻淬灭研究7，未能检测到在底物胺的存在下铜氧化态的变化。 有一种说法认为铜可能会减少8，但从未得到证实。 铜胺氧化酶含有另一种辅因子，最近被鉴定为6-羟基多巴醌（topa quinone）9，它被底物还原。 铜与底物还原酶的再氧化有关10-12，但未能检测到任何铜的氧化还原变化，导致有人提出Cu（II）作为刘易斯酸13，它在催化中具有间接作用14，或者它起结构作用6。 我们目前的证据表明，通过底物还原的几种胺氧化酶在厌氧条件下的Cu（I）-semiquinone状态的产生，并建议，Cu（I）-semiquinone可能是直接与氧反应的催化中间体。
THE role of copper in copper-containing amine oxidases has long been a source of debate and uncertainty1. Numerous electron paramagnetic resonance (EPR) experiments 2-6, including rapid freeze-quench studies 7, have failed to detect changes in the copper oxidation state in the presence of substrate amines. One suggestion that copper reduction might occur 8, has never been confirmed. Copper amine oxidases contain another cofactor, recently identified as 6-hydroxydopa quinone (topa quinone) 9, which is reduced by substrates. Copper has been implicated in the reoxidation of the substrate-reduce enzyme 10-12, but the failure to detect any copper redox change has led to proposals that Cu(II) acts as a Lewis acid 13, that it has an indirect role in catalysis 14, or that it serves a structural role 6. We present evidence for the generation of a Cu(I)-semiquinone state by substrate reduction of several amine oxidases under anaerobic conditions, and suggest that the Cu(I)-semiquinone may be the catalytic intermediate that reacts directly with oxygen.