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首页> 外文期刊>Journal of Molecular Biology >Structural evidence for direct hydride transfer from NADH to cytochrome P450nor
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Structural evidence for direct hydride transfer from NADH to cytochrome P450nor

机译：氢化物从NADH直接转移到细胞色素P450nor的结构证据

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摘要

Nitric oxide reductase cytochrome P450nor catalyzes an unusual reaction, direct electron transfer from NAD(P)H to bound heme. Here, we succeeded in determining the crystal structure of P450nor in a complex with an NADH analogue, nicotinic acid adenine dinucleotide, which provides conclusive evidence for the mechanism of the unprecedented electron transfer. Comparison of the structure with those of dinucleotide-free forms revealed a global conformational change accompanied by intriguing local movements caused by the binding of the pyridine nucleotide. Arg64 and Arg174 fix the pyrophosphate moiety upon the dinucleotide binding. Stereo-selective hydride transfer from NADH to NO-bound heme was suggested from the structure, the nicotinic acid ring being fixed near the heme by the conserved Thr residue in the I-helix and the upward-shifted propionate side-chain of the heme. A proton channel near the NADH channel is formed upon the dinucleotide binding, which should direct continuous transfer of the hydride and proton. A salt-bridge network (Glu71-Arg64-Asp88) was shown to be crucial for a high catalytic turnover. (C) 2004 Elsevier Ltd. All rights reserved.
机译：一氧化氮还原酶细胞色素P450也催化异常反应，将电子从NAD（P）H直接转移到结合的血红素上。在这里，我们成功地确定了与NADH类似物烟酸腺嘌呤二核苷酸的复合物中P450nor的晶体结构，这为空前的电子转移机理提供了确凿的证据。结构与无二核苷酸形式的结构的比较揭示了整体构象变化，伴随着由吡啶核苷酸的结合引起的有趣的局部运动。 Arg64和Arg174在二核苷酸结合时固定焦磷酸部分。从结构中暗示了从NADH到NO结合血红素的立体选择性氢化物转移，烟酸环通过I螺旋中的保守Thr残基和血红素的丙酸酯侧链向上固定在血红素附近。在二核苷酸结合时，在NADH通道附近形成一个质子通道，这应指导氢化物和质子的连续转移。盐桥网络（Glu71-Arg64-Asp88）被证明对于高催化转化率至关重要。 （C）2004 Elsevier Ltd.保留所有权利。

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