Configurational changes of heme followed by cytochrome c folding reaction
Configurational changes of heme followed by cytochrome c folding reaction
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DOI：
10.1039/c4mb00551a
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发表时间：
2015-01-01
影响因子：
--
通讯作者：
Majima, Tetsuro
中科院分区：
文献类型：
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作者：
Choi, Jungkweon;Cho, Dae Won;Majima, Tetsuro
虽然细胞色素c（Cyt-c），铁或亚铁Cyt-c的折叠动力学，已被广泛研究作为蛋白质折叠反应的范例，使用各种时间分辨光谱技术，血红素的构型变化与折叠反应从铁Cyt-c到亚铁Cyt-c诱导的单电子还原尚未阐明。为了解决这个问题，我们研究了血红素的构型变化的Cyt-c折叠过程中诱导的单电子还原使用的时间分辨共振拉曼光谱和脉冲辐解相结合。本文所呈现的结果揭示铁Cyt-c的还原和Met 80的连接在约2 μ s的时间尺度内同时发生，并且血红素的配体结合和交换取决于血红素的初始构型。在这项研究中观察到的Met 80的快速连接可能归因于Met 80分子内扩散到具有5配位高自旋构型的亚铁Cyt-c中。相反，具有6配位低自旋构型的亚铁Cyt-c的配体交换显著较慢。
Although the folding kinetics of cytochrome c (Cyt-c), ferric or ferrous Cyt-c, has been extensively investigated as a paradigm for a protein folding reaction using various time-resolved spectroscopic techniques, the configurational change of heme associated with the folding reaction from a ferric Cyt-c to a ferrous Cyt-c induced by one-electron reduction has not been elucidated. To address this issue, we investigated the configurational change of heme in the Cyt-c folding process induced by one-electron reduction using a combination of time-resolved resonance Raman spectroscopy and pulse radiolysis. The results presented herein reveal that the reduction of ferric Cyt-c and the ligation of Met80 occur simultaneously within a timescale of approximately 2 mu s, and that the ligand binding and exchange of heme depend on the initial configuration of the heme. The rapid ligation of Met80 observed in this study may be attributed to the intramolecular diffusion of Met80 into ferrous Cyt-c with a 5-coordinated high-spin configuration. Conversely, the ligand exchange of a ferrous Cyt-c with a 6-coordinated low-spin configuration was significantly slower.