Photoinduced electron transfer in the cytochrome c/cytochrome c oxidase complex using thiouredopyrenetrisulfonate-labeled cytochrome c. Optical multichannel detection.
Photoinduced electron transfer in the cytochrome c/cytochrome c oxidase complex using thiouredopyrenetrisulfonate-labeled cytochrome c. Optical multichannel detection.
复制标题
使用硫脲芘三磺酸盐标记的细胞色素 c 在细胞色素 c/细胞色素 c 氧化酶复合物中进行光诱导电子转移。
DOI：
10.1021/bi002341v
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发表时间：
2001
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：
Szundi,I;Cappuccio,JA;Borovok,N;Kotlyar,AB;Einarsdóttir,O
利用一种新型的光敏染料研究了细胞色素氧化酶/细胞色素复合物静电作用下的分子内电子转移。激光光解的硫脲芘三磺酸盐（TUPS），共价连接到半胱氨酸102酵母异-1-cytochromec，产生三重态的染料，这给一个电子的cytochromec，然后通过电子转移到cytochromecoxidase。在325和650 nm之间的100 ns至200 ms的延迟时间处收集时间分辨的光学吸收差光谱。基于奇异值分解（SVD）和多指数拟合，求解了三个表观寿命。提出了一个顺序的动力学机制，从中确定的微观速率常数和光谱的中间体。TUPS的三重态向细胞色素提供一个电子，其正向速率常数为1.2.0 × 104 s-1。三重态的一个重要部分在类似的时间尺度上返回到基态。细胞色素C还原后，电子从细胞色素C向CuA的转移速度加快，平衡有利于还原的细胞色素C。随后，CuA与血红素平衡，表观速率常数为10.1 × 104 s-1。在毫秒的时间尺度上，氧化的TUPS返回到基态，血红素被再氧化。提取的中间体光谱与假设的中间体的模型光谱非常一致，支持所提出的机制。
Intramolecular electron transfer in the electrostatic cytochromecoxidase/cytochromeccomplex was investigated using a novel photoactivatable dye. Laser photolysis of thiouredopyrenetrisulfonate (TUPS), covalently linked to cysteine 102 on yeast iso-1-cytochromec, generates a triplet state of the dye, which donates an electron to cytochromec, followed by electron transfer to cytochromecoxidase. Time-resolved optical absorption difference spectra were collected at delay times from 100 ns to 200 ms between 325 and 650 nm. On the basis of singular value decomposition (SVD) and multiexponential fitting, three apparent lifetimes were resolved. A sequential kinetic mechanism is proposed from which the microscopic rate constants and spectra of the intermediates were determined. The triplet state of TUPS donates an electron to cytochromecwith a forward rate constant of ∼2.0 × 104s-1. A significant fraction of the triplet returns back to the ground state on a similar time scale. The reduction of cytochromecis followed by faster electron transfer from cytochromecto CuA, with the equilibrium favoring the reduced cytochromec. Subsequently, CuAequilibrates with hemeawith an apparent rate constant of ∼1 × 104s-1. On a millisecond time scale, the oxidized TUPS returns to the ground state and hemeabecomes reoxidized. The extracted intermediate spectra are in excellent agreement with model spectra of the postulated intermediates, supporting the proposed mechanism.