Low-frequency mode activity of heme: femtosecond coherence spectroscopy of iron porphine halides and nitrophorin.
Low-frequency mode activity of heme: femtosecond coherence spectroscopy of iron porphine halides and nitrophorin.
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DOI：
10.1021/ja800916d
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发表时间：
2008-07-30
影响因子：
15
通讯作者：
Champion, Paul M.
中科院分区：
文献类型：
--
作者：
Kubo, Minoru;Gruia, Flaviu;Benabbas, Abdelkrim;Barabanschikov, Alexander;Montfort, William R.;Maes, Estelle M.;Champion, Paul M.
用飞秒相干光谱(FCS)结合偏振共振拉曼光谱和密度泛函理论(DFT)研究了金属卟啉对卤化铁卟啉(Fe(P)(X)，X=Cl，Br)和亚硝基4(NP4)的低频模活性。证实了FCS的模式对称性选择规则与拉曼散射相同，在Soret共振条件下观察到了Fe(P)(X)的Franck-Condon和Jahn-Teller模活动。密度泛函理论计算的低频(20-400 cm-1)模及其在卤化物取代后的频移与实验的拉曼和相干数据符合得很好，从而可以作出模的指认。Fe(P)(Cl)的穹顶模式位于~80 cm-1，Fe(P)(Br)的穹顶模式位于~60 cm-1。用相干技术对NP4进行了研究，铁和铁的非结合态NP4在~30-40 cm-1处表现出一种与未光解后的瞬时血红素穹顶运动有关的模式。还研究了三种不同程度的血红素褶皱扭曲的NP4铁衍生物的相干光谱。我们发现在~60 cm~(-1)处有一个模，其相干谱中的相对强度与褶皱失真的大小成二次关系。为了定量地解释这种关联，提出了一种新的“失真诱导”拉曼增强机制。这种机制是分子框架的低频“软模式”所独有的，这种模式可能会被环境作用力扭曲。这些结果表明，FCS有可能作为一种灵敏的探针来研究由蛋白质环境力或水相化学反应引起的动态和重要的非平面血红素振动激发。
The low-frequency mode activity of metalloporphyrins has been studied for iron porphine-halides (Fe(P)(X), X = Cl, Br) and nitrophorin 4 (NP4) using femtosecond coherence spectroscopy (FCS) in combination with polarized resonance Raman spectroscopy and density functional theory (DFT). It is confirmed that the mode symmetry selection rules for FCS are the same as for Raman scattering and that both Franck-Condon and Jahn-Teller mode activities are observed for Fe(P)(X) under Soret resonance conditions. The DFT-calculated low-frequency (20-400 cm-1) modes, and their frequency shifts upon halide substitution, are in good agreement with experimental Raman and coherence data, so that mode assignments can be made. The doming mode is located at ~80 cm-1 for Fe(P)(Cl) and at ~60 cm-1 for Fe(P)(Br). NP4 is also studied with coherence techniques, and the NO-bound species of ferric and ferrous NP4 display a mode at ~30-40 cm-1 that is associated with transient heme doming motion following NO photolysis. The coherence spectra of three ferric derivatives of NP4 with different degrees of heme ruffling distortion are also investigated. We find a mode at ~60 cm-1 whose relative intensity in the coherence spectra depends quadratically on the magnitude of the ruffling distortion. To quantitatively account for this correlation, a new “distortion-induced” Raman enhancement mechanism is presented. This mechanism is unique to low-frequency “soft modes” of the molecular framework that can be distorted by environmental forces. These results demonstrate the potential of FCS as a sensitive probe of dynamic and functionally important nonplanar heme vibrational excitations that are induced by the protein environmental forces or by the chemical reactions in the aqueous phase.
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影响因子：
2.9
作者：
Andersen, JF;Champagne, DE;Montfort, WR
通讯作者：
Montfort, WR
影响因子：
64.8
作者：
DANTUS, M;BOWMAN, RM;ZEWAIL, AH
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ZEWAIL, AH
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3.4
作者：
Giraud, G;Karolin, J;Wynne, K
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影响因子：
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作者：
Gruia, Flavin;Ionascu, Dan;Champion, Paul M.
通讯作者：
Champion, Paul M.
影响因子：
56.9
作者：
FRAUENFELDER, H;SLIGAR, SG;WOLYNES, PG
通讯作者：
WOLYNES, PG