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首页> 外文期刊>The journal of physical chemistry, B. Condensed matter, materials, surfaces, interfaces & biophysical >Hole Hopping through Cytochrome P450
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Hole Hopping through Cytochrome P450

机译：通过细胞色素p450跳跃

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摘要

High-potential iron-oxo species are intermediates in the catalytic cycles of oxygenase enzymes. They can cause heme degradation and irreversible oxidation of nearby amino acids. We have proposed that there are protective mechanisms in which hole hopping from oxidized hemes through tryptophan/tyrosine chains generates a surface-exposed amino-acid oxidant that could be rapidly disarmed by reaction with cellular reductants. In investigations of cytochrome P450(BM3), we identified Trp96 as a critical residue that could play such a protective role. This Trp is cation-pi paired with Arg398 in 81% of mammalian P450s. Here we report on the effect of the Trp/Arg cation-pi interaction on Trp96 formal potentials as well as on electronic coupling strengths between Trp96 and the heme both for wild type cytochrome P450 and selected mutants. Mutation of Arg398 to His, which decreases the Trp96 formal potential, increases Trp-heme electronic coupling; however, surprisingly, the rate of phototriggered electron transfer from a Ru-sensitizer (through Trp96) to the P450(BM3) heme was unaffected by the Arg398His mutation. We conclude that Trp96 has moved away from Arg398, suggesting that the protective mechanism for P450s with this Trp-Arg pair is conformationally gated.
机译：高潜能的铁氧藻物种是氧酶催化循环中的中间体。它们可以引起附近氨基酸的血红液降解和不可逆的氧化。我们提出存在有保护机制，其中通过色氨酸/酪氨酸链从氧化血液中跳跃产生表面暴露的氨基酸氧化剂，其可以通过与细胞还原剂反应迅速撤销。在对细胞色素P450（BM3）的研究中，我们将TRP96确定为可能发挥这种保护作用的关键残留物。该TRP是在81％的哺乳动物P450S中与Arg398配对的阳离子PI。在这里，我们报告了TRP / ARG阳离子-PI相互作用对TRP96正式电位的影响以及TRP96与野生型细胞色素P450和所选突变体之间的血红素之间的电子耦合强度。 ARG398对他的突变降低了TRP96正式潜力，增加了TRP-HEME电子耦合;然而，令人惊讶的是，从Ru-敏化剂（通过TRP96）到P450（BM3）血红素的光电电子转移的速率不受ARG398HIS突变的影响。我们得出结论，TRP96已经远离ARG398，表明P450S与该TRP-ARG对的保护机制是一致的。

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