Site-specific collapse dynamics guide the formation of the cytochrome c′ four-helix bundle
Site-specific collapse dynamics guide the formation of the cytochrome c′ four-helix bundle
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DOI：
10.1073/pnas.0609413103
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发表时间：
2007-01-02
影响因子：
11.1
通讯作者：
Winkler, Jay R.
中科院分区：
文献类型：
--
作者：
Kimura, Tetsunari;Lee, Jennifer C.;Winkler, Jay R.
通过对沼泽红假单胞菌细胞色素c‘折叠过程中荧光能量转移动力学的分析，提取了色氨酸到血红素(W/heme)距离分布的演变，揭示了两个变异体[W32(Q1A/F32W1W72F)和W72(Q1A)]之间的显著差异。在连续流动混合器(150MU S)所能获得的最早时间点上测量的W32/血红素和W72/血红素距离分布都证实了多肽系综没有均匀坍塌，也没有形成天然结构。时间分辨荧光光谱表明，W32在S折叠的第一个700亩时被隔离在水溶液中，而W72仍然暴露在溶剂中。W32/血红素距离分布的一阶矩演化到原始值的速度比W72快，这表明W32比W72更接近血红素。
The evolution of tryptophan-to-heme (W/heme) distance distributions extracted from analysis of fluorescence energy transfer kinetics during the refolding of Rhodopseudomonas palustris cytochrome c' reveals dramatic differences between two variants [W32 (Q1A/F32W1W72F) and W72 (Q1A)]. Both W32/heme and W72/heme distance distributions measured at the earliest time point attainable with a continuous-flow mixer (150 mu s) confirm that the polypeptide ensemble is not uniformly collapsed and that native structure is not formed. Time-resolved fluorescence spectra indicate that W32 is sequestered from the aqueous solution during the first 700 mu s of folding, whereas W72 remains exposed to solvent. The first moment of the W32/heme distance distribution evolves to its native value faster than that of W72, suggesting that the approach of W32 to the heme precedes that of W72.