MEMBRANE-ASSOCIATED REDOX CYCLING OF COPPER MEDIATES HYDROPEROXIDE TOXICITY IN ESCHERICHIA-COLI
MEMBRANE-ASSOCIATED REDOX CYCLING OF COPPER MEDIATES HYDROPEROXIDE TOXICITY IN ESCHERICHIA-COLI
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DOI：
10.1016/0005-2728(93)90033-c
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发表时间：
1993-08-16
期刊：
影响因子：
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通讯作者：
MASSA, EM
中科院分区：
文献类型：
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作者：
RODRIGUEZMONTELONGO, L;DELACRUZRODRIGUEZ, LC;MASSA, EM
我们正在研究叔丁基过氧化氢 (t-BOOH) 对大肠杆菌的作用，作为过氧化物毒性的模型系统。在我们之前的报告（De la Cruz-Rodriguez, L.C.、Farias, R.N. 和 Massa, E.M. (1990) Biochim. Biophys. Acta 1015, 510-516）中，呼吸链被确定为 t-BOOH 的主要靶标。在本文中，我们进一步研究了t-BOOH对大肠杆菌呼吸链NADH氧化酶的影响，以阐明损伤机制，特别是所涉及的金属离子的身份和作用。结果是： (a) t-BOOH 毒性是由膜结合铜离子介导的； (b) 在 NADH 和其他呼吸底物（琥珀酸盐、D-乳酸）存在下，一小部分膜结合铜从 Cu(II) 还原为 Cu(I)； (c) 铜的这种还原发生在 37 摄氏度，但不是在 0 摄氏度，或者当膜因之前的加热而失活时； (d) 在膜与 NADH 预孵育过程中，通过还原 Cu(II) 生成的 Cu(I) 被 t-BOOH 氧化，同时 NADH 氧化酶失活，而仅用 t-BOOH（不含 NADH）处理对氧化酶没有影响。结论是t-BOOH对呼吸链的影响是由铜的氧化还原循环介导的。据推测，这种损害是由于氢过氧化物在位点特异性芬顿型反应中与 Cu(I) 相互作用而被激活所致。
We are studying the action of tert-butylhydroperoxide (t-BOOH) on Escherichia coli as a model system for peroxide toxicity. In our previous report (De la Cruz-Rodriguez, L.C., Farias, R.N. and Massa, E.M. (1990) Biochim. Biophys. Acta 1015, 510-516), the respiratory chain was identified as a major target of t-BOOH. In the present paper, we study further the effect of t-BOOH on the NADH oxidase of the E. coli respiratory chain to clarify the mechanism of damage, especially regarding the identity and role of the metal -ion involved. The results are: (a) t-BOOH toxicity is mediated by membrane-bound copper ions; (b) a small pool of the membrane-bound copper is reduced from Cu(II) to Cu(I) in the presence of NADH and other respiratory substrates (succinate, D-lactate); (c) this reduction of copper occurs at 37-degrees-C but not at 0-degrees-C or when the membranes are inactivated by previous heating; (d) the Cu(I) generated by reduction of Cu(II) during membrane preincubation with NADH, is oxidized by t-BOOH with simultaneous inactivation of the NADH oxidase, whereas treatment with only t-BOOH (without NADH) has no effect on the oxidase. It is concluded that the effect of t-BOOH on the respiratory chain is mediated by redox cycling of copper. It is proposed that the damage results from activation of the hydroperoxide through its interaction with Cu(I) in a site-specific Fenton-type reaction.