Parr S R, Barber D, Greenwood C, Brunori M
Biochem J. 1977 Nov 1;167(2):447-55. doi: 10.1042/bj1670447.
A stopped-flow investigation of the electron-transfer reaction between oxidized azurin and reduced Pseudomonas aeruginosa cytochrome c-551 oxidase and between reduced azurin and oxidized Ps. aeruginosa cytochrome c-551 oxidase was performed. Electrons leave and enter the oxidase molecule via its haem c component, with the oxidation and reduction of the haem d1 occurring by internal electron transfer. The reaction mechanism in both directions is complex. In the direction of oxidase oxidation, two phases assigned on the basis of difference spectra to haem c proceed with rate constants of 3.2 X 10(5)M-1-S-1 and 2.0 X 10(4)M-1-S-1, whereas the haem d1 oxidation occurs at 0.35 +/- 0.1S-1. Addition of CO to the reduced enzyme profoundly modifies the rate of haem c oxidation, with the faster process tending towards a rate limit of 200S-1. Reduction of the oxidase was similarly complex, with a fast haem c phase tending to a rate limit of 120S-1, and a slower phase with a second-order rate of 1.5 X 10(4)M-1-S-1; the internal transfer rate in this direction was o.25 +/- 0.1S-1. These results have been applied to a kinetic model originally developed from temperature-jump studies.
对氧化型天青蛋白与还原型铜绿假单胞菌细胞色素c-551氧化酶之间以及还原型天青蛋白与氧化型铜绿假单胞菌细胞色素c-551氧化酶之间的电子转移反应进行了停流研究。电子通过其血红素c组分离开和进入氧化酶分子，血红素d1的氧化和还原通过内部电子转移发生。两个方向的反应机制都很复杂。在氧化酶氧化方向上，根据差光谱确定的两个与血红素c相关的阶段，其速率常数分别为3.2×10⁵M⁻¹·s⁻¹和2.0×10⁴M⁻¹·s⁻¹，而血红素d1的氧化速率为0.35±0.1s⁻¹。向还原型酶中添加一氧化碳会深刻改变血红素c的氧化速率，较快的过程趋向于200s⁻¹的速率极限。氧化酶的还原同样复杂，快速的血红素c阶段趋向于120s⁻¹的速率极限，较慢的阶段二级速率为1.5×10⁴M⁻¹·s⁻¹；这个方向的内部转移速率为0.25±0.1s⁻¹。这些结果已应用于最初从温度跃变研究中发展而来的动力学模型。
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