Dissecting Nanosecond Dynamics in Membrane Proteins with Dipolar Relaxation upon Tryptophan Photoexcitation.
Dissecting Nanosecond Dynamics in Membrane Proteins with Dipolar Relaxation upon Tryptophan Photoexcitation.
复制标题
色氨酸光激发偶极弛豫剖析膜蛋白的纳秒动力学
DOI：
10.1021/acs.jpclett.8b00834
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Keller
中科院分区：
文献类型：
--
作者：
Frotscher;Krainer;Schlierf;Keller
蛋白质在纳秒时间尺度上的结构动力学可以用偶极弛豫来探测，以响应内在色氨酸（Trp）残基的光激发。然而，对于膜蛋白，由于蛋白质本身，膜模拟物和水性溶剂的重叠贡献的复杂性损害了详细的分析和解释。为了解开这些贡献，我们测量了时间分辨发射光谱的色氨酸在蛋白质Mistic在洗涤剂胶束的各种极性。通过与Trp类似物在水和胶束中的比较，我们可以剖析水合作用、胶束和蛋白质基质对纳秒时间尺度上偶极弛豫的贡献。我们的研究结果表明，超快，亚纳秒弛豫报告色氨酸屏蔽水的程度，胶束和蛋白质部分作出添加剂的贡献。相比之下，在低纳秒制度的松弛是由于偶极重排的胶束和蛋白质部分光激发后，从而探测周围的固有荧光团的构象动力学。
The structural dynamics of proteins on the nanosecond time scale can be probed with dipolar relaxation in response to photoexcitation of intrinsic tryptophan (Trp) residues. For membrane proteins, however, the complexity due to overlapping contributions from the protein itself, the membrane mimic, and the aqueous solvent impairs detailed analysis and interpretation. To disentangle these contributions, we measured time-resolved emission spectra of Trp in the protein Mistic in detergent micelles of various polarities. By comparison with Trp analogues in water and micelles, we could dissect the contributions from hydration, micelle, and protein matrix to dipolar relaxation on the nanosecond time scale. Our results demonstrate that ultrafast, subnanosecond relaxation reports on the extent of Trp shielding from water, with micelle and protein moieties making additive contributions. By contrast, relaxation in the low nanosecond regime is due to dipolar rearrangement of micelle and protein moieties upon photoexcitation, thereby probing conformational dynamics around the intrinsic fluorophore.