Light-induced spectral changes in fully oxidized cytochrome c oxidase in the presence of oxygen.
Light-induced spectral changes in fully oxidized cytochrome c oxidase in the presence of oxygen.
复制标题
在氧气存在下，完全氧化的细胞色素 C 氧化酶中光诱导的光谱变化。
DOI：
10.1021/bi9630321
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发表时间：
1997
期刊：
影响因子：
--
通讯作者：
Einarsdottir,O
中科院分区：
文献类型：
--
作者：
Brooks,JL;Sucheta,A;Einarsdottir,O
氧化的细胞色素氧化酶在300 nm以下的低强度(<；2 mW)光下，在氧气存在下会引起Soret和可见光区域随pH变化的光谱变化。在可见光区，SORET区在438 nm处有一个峰，在414 nm处有一个低谷；在可见光区，在606 nm处有一个峰，在∼577 nm处有一个肩峰。这种作用被氰化物抑制，提示细胞色素3参与了这一作用。PH依赖关系显示了两个可滴定的基团，pKavue分别为6.52±0.26和6.85±0.15。光谱变化类似于将过氧化氢添加到完全氧化的酶中时发生的变化，这导致了当参照氧化酶时具有607和580 nm的最大吸光度的物种的混合物。过氧化氢酶的加入影响了光谱变化的初始开始，并增加了光照终止时发生逆转反应的速率。这些数据与光诱导双核中心自动还原和随后的O2结合，随后过氧化氢的释放和形成607 nm和580 nm的混合物的机制是一致的。
Illumination of oxidized cytochrome oxidase with low intensity (<2 mW) light below 300 nm in the presence of oxygen causes pH-dependent spectral changes in the Soret and visible regions. The light-induced difference spectra show a peak at 438 nm and a trough at 414 nm in the Soret region and a peak at 606 nm and a shoulder at ∼577 nm in the visible region. The effect was inhibited by cyanide, suggesting the involvement of cytochromea3. The pH dependence indicates two titratable groups with pKavalues of 6.52 ± 0.26 and 6.85 ± 0.15. The spectral changes are analogous to those occurring upon addition of hydrogen peroxide to the fully oxidized enzyme, which results in a mixture of species with absorbance maxima at 607 and 580 nm when referenced against the oxidized enzyme. Catalase addition affected the initial onset of the spectral change and increased the rate at which the reverse reaction occurred upon termination of illumination. The data are consistent with a mechanism involving light-induced autoreduction of the binuclear center and subsequent O2binding, followed by the release of hydrogen peroxide and the formation of a mixture of the 607 nm and 580 nm forms.