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首页> 外文期刊>Biochemistry >Mechanism of cytochrome c oxidase-catalyzed reduction of dioxygen to water: evidence for peroxy and ferryl intermediates at room temperature.
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Mechanism of cytochrome c oxidase-catalyzed reduction of dioxygen to water: evidence for peroxy and ferryl intermediates at room temperature.

机译：细胞色素C氧化酶催化的双氧还原为水的机理：室温下过氧和Ferry中间体的证据。

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The reaction between bovine heart cytochrome oxidase and dioxygen was investigated at room temperature following photolysis of the fully reduced CO-bound enzyme. Time-resolved optical absorption difference spectra were collected by a gated multichannel analyzer in the visible region (lambda = 460-720 nm) from 50 ns to 50 ms after photolysis. Singular value decomposition (SVD) analysis indicated the presence of at least seven intermediates. Multiexponential fitting gave the following apparent lifetimes: 1.2 microseconds, 10 microseconds, 25 microseconds, 32 microseconds, 86 microseconds, and 1.3 ms. On the basis of the SVD results and a double difference map, a sequential kinetic mechanism is proposed from which the spectra and time-dependent populations of the reaction intermediates were determined. The ferrous-oxy complex (compound A), with a peak at 595 nm and a trough at 612 nm versus the reduced enzyme, reaches a maximum concentration approximately 30 microseconds after photolysis. It decays to a 1:6 mixture of peroxy species (a3(3+)-O(-)-O-) in which cytochrome a is reduced and oxidized. Cytochrome a3 in both species has a peak at 606 nm versus its oxidized form. The peroxy species decay to a ferryl intermediate, with a peak at 578 nm versus the oxidized enzyme, followed by electron redistribution between CuA and cytochrome a. The two ferryl species reach a maximum concentration approximately 310 microseconds after photolysis. The excellent agreement between the experimental and theoretical spectra of the intermediates provides unequivocal evidence for the presence of peroxy and ferryl species during dioxygen reduction by cytochrome oxidase at room temperature.
机译：在完全还原的与CO结合的酶光解后，在室温下研究了牛心脏细胞色素氧化酶与双氧之间的反应。通过门控多通道分析仪在光解后50 ns至50 ms的可见光区域（λ= 460-720 nm）中收集时间分辨的光吸收差异光谱。奇异值分解（SVD）分析表明存在至少七个中间体。多指数拟合给出以下表观寿命：1.2微秒，10微秒，25微秒，32微秒，86微秒和1.3 ms。基于SVD结果和双差图，提出了一种顺序动力学机制，从中确定了反应中间体的光谱和时间依赖性种群。与还原的酶相比，亚铁-氧配合物（化合物A）的峰在595 nm处，波谷在612 nm处，在光解后约30微秒达到最大浓度。它衰变成过氧物质（a3（3 +）-O（-）-O-）的1：6混合物，其中细胞色素a被还原和氧化。相对于其氧化形式，两种物质中的细胞色素a3在606 nm处都有一个峰。过氧物质衰减成一个ferryl中间体，相对于被氧化的酶在578 nm处有一个峰，然后CuA和细胞色素a之间发生电子再分布。在光解之后，两种小轮藻物种的最大浓度达到约310微秒。中间体的实验光谱与理论光谱之间的出色一致性为室温下细胞色素氧化酶还原双氧过程中过氧和亚铁物种的存在提供了明确的证据。

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