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首页> 外文期刊>Biochemistry >Resonance Raman characterization of the ammonia-generated oxo intermediate of cytochrome c oxidase from Paracoccus denitrificans
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Resonance Raman characterization of the ammonia-generated oxo intermediate of cytochrome c oxidase from Paracoccus denitrificans

机译：反硝化副球菌细胞色素C氧化酶氨生成的羰基合成中间体的共振拉曼表征

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摘要

A novel oxo state of cytochrome c oxidase from Paracoccus denitrificans generated by successive addition of excess H_2O_2 and ammonia was investigated using resonance Raman (RR) spectroscopy. Addition of ammonia to the H_2O_2-generated artificial F state resulted in an upshift of the oxoferryl stretching vibration from 790 to 796 cm ~(-1), indicating that ammonia influences ligation of the heme-bound oxygen in the binuclear center. Concomitantly performed RR measurements in the high-frequency region between 1300 and 1700 cm~(-1) showed a high-spin to low-spin transition of heme a3 upon generation of the F state that was not altered by addition of ammonia. Removal of H_2O_2 by addition of catalase resulted in the disappearance of the oxoferryl stretching vibration and major back transformation of heme a_3 into the high-spin state. The ratio of high-spin to low-spin states was identical for intermediates created with and without ammonia, leading to the conclusion that ammonia does not interact directly with heme a_3. Only for the ammonia-created state was a band at 612 nm observed in the UV-visible difference spectrum that was shifted to 608 nm after addition of catalase. Our results support the hypothesis by von der Hocht et al. [von der Hocht, I., et al. (2011) Proc. Natl. Acad. Sci. U.S.A. 108, 3964-3969] that addition of ammonia creates a novel oxo intermediate state called P_N where ammonia binds to Cu_B once the oxo intermediate F state has been formed.
机译：使用共振拉曼光谱研究了通过连续添加过量的H_2O_2和氨水而产生的反硝化副球菌细胞色素c氧化酶的一种新的氧化态。 H_2O_2生成的人工F状态中添加氨导致草酰氧的拉伸振动从790 cm〜（-1）升至796 cm〜（-1），表明氨影响双核中心血红素结合氧的连接。在1300和1700 cm〜（-1）之间的高频区域中同时进行的RR测量表明，在生成F状态时血红素a3由高自旋转变为低自旋转变，而不会因添加氨而改变。通过添加过氧化氢酶去除H_2O_2导致草酰氧伸展振动消失，血红素a_3大量向后转化为高自旋状态。对于有和没有氨的中间体，高自旋态与低自旋态的比率是相同的，从而得出结论，氨不会直接与血红素a_3相互作用。仅对于氨生成状态，在添加了过氧化氢酶后，在紫外可见差异光谱中观察到的一条在612 nm处的谱带移至608 nm。我们的结果支持von der Hocht等人的假设。 [von der Hocht，I.等。 （2011）Proc。 Natl。学院科学[U.S.A. 108，3964-3969]指出，添加氨会形成一种称为P_N的新的羰基中间体状态，一旦形成了羰基中间体F状态，氨就会与Cu_B结合。

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