Electron-transfer kinetics of zinc-substituted cytochrome c and its Ru(NH3)5(histidine-33) derivative
Electron-transfer kinetics of zinc-substituted cytochrome c and its Ru(NH3)5(histidine-33) derivative
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锌取代细胞色素c及其Ru(NH3)5(histidine-33)衍生物的电子转移动力学
DOI：
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发表时间：
1988
期刊：
影响因子：
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通讯作者：
J. Winkler
中科院分区：
文献类型：
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作者：
H. Elias;M. Chou;J. Winkler
三重态锌取代马心细胞色素c双分子电子转移动力学（Zn-cyt c*）至Ru（NH/sub 3/）/sub 5/L/sup 3 +/已被测量（L = NH/sub 3/，k（298 K）= 1.4 × 10/sup 7/ M/sup-1/ s/sup-1/; L =组氨酸，k（298 K）= 2.4 × 10/sup 7/ M/sup-1/ s/sup-1/），沿着相应的热逆反应（L = NH/sub 3/，k（298 K）= 1.5 x 10/sup 8/ M/sup-1/ s/sup-1/; L =组氨酸，k（298 K）= 3.6 x 10/sup 8/ M/sup-1/ s/sup-1/）。衍生化金属蛋白钌五氨合组氨酸-33-锌取代的细胞色素c（Ru-Zn-cyt c）的制备和其特征在于其胰蛋白酶消化片段的原子吸收光谱和HPLC分析。从三重态激发的Zn-卟啉部分到11.8-A远Ru的蛋白内电子转移速率（NH/sub 3/）/sub 5/（His-33）/sup 3 +/残基（k（298 K）= 7.7 × 10/sup 5/ s/sup-1/），以及热逆反应的（k（298 K）= 1.6 × 10/sup 6/ s/sup-1/），已经通过瞬态光谱测量。Ru（II）的蛋白内电子转移猝灭Zn-cyt c* 的速率常数为2.4 × 10 ~（-1）/ s/sup ~（-1）/。这些动力学是根据电子转移反应的半经典理论讨论的。«少
The kinetics of the bimolecular electron transfers from triplet-excited zinc-substituted horse heart cytochrome c (Zn-cyt c*) to Ru(NH/sub 3/)/sub 5/L/sup 3 +/ have been measured (L = NH/sub 3/, k(298 K) = 1.4 x 10/sup 7/ M/sup -1/ s/sup -1/; L = histidine, k(298 K) = 2.4 x 10/sup 7/ M/sup -1/ s/sup -1/), along with those of the corresponding thermal back-reactions (L = NH/sub 3/, k(298 K) = 1.5 x 10/sup 8/ M/sup -1/ s/sup -1/; L = histidine, k(298 K) = 3.6 x 10/sup 8/ M/sup -1/ s/sup -1/). The derivatized metalloprotein ruthenium pentaammine histidine-33-zinc-substituted cytochrome c (Ru-Zn-cyt c) has been prepared and characterized by atomic absorption spectroscopy and HPLC analysis of its tryptic digestion fragments. The rate of intraprotein electron transfer from the triplet-excited Zn-porphyrin moiety to the 11.8-A distant Ru(NH/sub 3/)/sub 5/(His-33)/sup 3 +/ residue (k(298 K) = 7.7 x 10/sup 5/ s/sup -1/), as well as that of the thermal back-reaction (k(298 K) = 1.6 x 10/sup 6/ s/sup -1/), has been measured by transient spectroscopy. Intraprotein electron transfer from Ru(II) quenches Zn-cyt c* with a rate constant of 2.4 x 10/sup 2/ s/sup -1/. These kinetics are discussed in terms of the semiclassical theorymore » of electron-transfer reactions.« less