Ultrafast quenching of tryptophan fluorescence in proteins: Interresidue and intrahelical electron transfer
Ultrafast quenching of tryptophan fluorescence in proteins: Interresidue and intrahelical electron transfer
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DOI：
10.1016/j.chemphys.2008.01.061
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发表时间：
2008-06-23
期刊：
影响因子：
2.3
通讯作者：
Zhong, Dongping
中科院分区：
文献类型：
--
作者：
Qiu, Weihong;Li, Tanping;Zhong, Dongping
蛋白质中色氨酸荧光的猝灭对于使用色氨酸作为分子光学探针了解蛋白质动力学和酶反应至关重要。我们在这里报告我们的潜在淬灭残基与40多种蛋白质的系统检查。通过定点突变，我们将色氨酸置于所需的位置或改变其邻近的残基，以筛选20个氨基酸残基和肽骨架的猝灭基团。在飞秒分辨率下，我们观察到了100 ps内的超快猝灭动力学，并确定了两个超快猝灭基团，羰基和含硫残基。前者是谷氨酰胺和谷氨酸残基，后者是二硫键和半胱氨酸残基。由肽键羰基以及其他潜在的残基的淬灭大多发生在长于100 ps。这些超快猝灭动力学发生在货车德瓦耳斯距离通过蛋白质内电子转移具有高方向性。在最佳分子轨道重叠之后，电子从吲哚部分的苯环以垂直取向跳跃到受体猝灭残基的LUMO。分子动力学模拟被调用来阐明各种相关性的猝灭动力学与分离距离，相对取向，局部波动和反应的异质性。这些独特的超快猝灭对，最近发现广泛发生在高分辨率蛋白质结构，可能具有重要的生物学意义。(C)2008 Elsevier B.V.保留所有权利。
Quenching of tryptophan fluorescence in proteins has been critical to the understanding of protein dynamics and enzyme reactions using tryptophan as a molecular optical probe. We report here our systematic examinations of potential quenching residues with more than 40 proteins. With site-directed mutation, we placed tryptophan to desired positions or altered its neighboring residues to screen quenching groups among 20 amino acid residues and of peptide backbones. With femtosecond resolution, we observed the ultrafast quenching dynamics within 100 ps and identified two ultrafast quenching groups, the carbonyl- and sulfur-containing residues. The former is glutamine and glutamate residues and the later is disulfide bond and cysteine residue. The quenching by the peptide-bond carbonyl group as well as other potential residues mostly occurs in longer than 100 ps. These ultrafast quenching dynamics occur at van der Waals distances through intraprotein electron transfer with high directionality. Following optimal molecular orbital overlap, electron jumps from the benzene ring of the indole moiety in a vertical orientation to the LUMO of acceptor quenching residues. Molecular dynamics simulations were invoked to elucidate various correlations of quenching dynamics with separation distances, relative orientations, local fluctuations and reaction heterogeneity. These unique ultrafast quenching pairs, as recently found to extensively occur in high-resolution protein structures, may have significant biological implications. (C) 2008 Elsevier B.V. All rights reserved.