Intermediates in the reaction of fully reduced cytochrome c oxidase with dioxygen.
Intermediates in the reaction of fully reduced cytochrome c oxidase with dioxygen.
复制标题
完全还原的细胞色素 C 氧化酶与双氧反应的中间体。
DOI：
10.1021/bi981092w
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发表时间：
1998
期刊：
影响因子：
2.9
通讯作者：
Einarsdóttir,O
中科院分区：
文献类型：
--
作者：
Sucheta,A;Szundi,I;Einarsdóttir,O
细胞色素氧化酶的水分子氧的减少，监测在索雷特地区的光解后，充分减少CO复合物。在373和521 nm之间收集的时间分辨的光吸收差光谱测量延迟时间从50 ns到50 ms，并使用奇异值分解和多指数拟合进行分析。五个过程被解决的表观寿命为0.9 μs，8 μs，36 μs，103 μs，和1.2 ms。提出了一种机制和光谱的中间体提取和比较模型光谱的假设的中间体。该模型建立在仅使用可见光区数据的早期机制上（Sucheta et al.（1997）Biochemistry 36，554 - 565），并提供了一个更完整的机制，适合两个光谱区的结果。在中间体3中，亚铁-氧络合物（化合物A）衰变为607 nm的物质，通常称为P，其在明显更快的时间尺度上转化为580 nm的铁基形式（Fo）。P和Fo之间的平衡常数为1。我们推测P的结构是a34 +O CuB 2 +− OH-，氧化等价物位于靠近双核中心的酪氨酸244上。当P转化为Fo时，细胞色素将一个电子给酪氨酸自由基，形成酪氨酸。随后，质子被酪氨酸吸收，形成FI[a34+O CuB 2 +-OH-a3+CuA+]。随后，电子从CuA快速转移到细胞色素，产生FIB [a34+O CuB 2 +−OH-a2+ CuA 2 +]。
The reduction of dioxygen to water by cytochromecoxidase was monitored in the Soret region following photolysis of the fully reduced CO complex. Time-resolved optical absorption difference spectra collected between 373 and 521 nm were measured at delay times from 50 ns to 50 ms and analyzed using singular value decomposition and multiexponential fitting. Five processes were resolved with apparent lifetimes of 0.9 μs, 8 μs, 36 μs, 103 μs, and 1.2 ms. A mechanism is proposed and spectra of intermediates are extracted and compared to model spectra of the postulated intermediates. The model builds on an earlier mechanism that used data only from the visible region (Sucheta et al. (1997)Biochemistry36, 554−565) and provides a more complete mechanism that fits results from both spectral regions. Intermediate 3, the ferrous−oxy complex (compound A) decays into a 607 nm species, generally referred to as P, which is converted to a 580 nm ferryl form (Fo) on a significantly faster time scale. The equilibrium constant between P and Fois 1. We propose that the structure of P isa34+O CuB2+−OH-with an oxidizing equivalent residing on tyrosine 244, located close to the binuclear center. Upon conversion of P to Fo, cytochromeadonates an electron to the tyrosine radical, forming tyrosinate. Subsequently a proton is taken up by tyrosinate, forming FI[a34+O CuB2+−OH-a3+CuA+]. This is followed by rapid electron transfer from CuAto cytochromeato produce FII[a34+O CuB2+−OH-a2+CuA2+].