Picosecond dynamics of a membrane protein revealed by 2D IR
Picosecond dynamics of a membrane protein revealed by 2D IR
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DOI：
10.1073/pnas.0508833103
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发表时间：
2006-03-07
影响因子：
11.1
通讯作者：
Zanni, MT
中科院分区：
文献类型：
--
作者：
Mukherjee, P;Kass, I;Zanni, MT
快速的蛋白质动力学可能会被观察时间相对较慢的技术错过。使用二维红外光谱和同位素标记，我们已经探讨了快速，皮秒动力学的膜蛋白在其天然环境。通过测量11个酰胺1模式（骨架羰基拉伸）的均匀和不均匀的IR线宽，我们已经捕获了CD 3 xi蛋白沿着其跨膜段的结构分布和动力学，这些结构分布和动力学随着较慢的时间尺度技术而丢失。我们发现，齐次寿命和人口弛豫时间是相同的几乎所有的残留物。与此相反，不均匀的线宽变化显着，最大的不均匀分布发生在N末端附近的残基和中心附近的最窄处。这种行为是高度一致的，最近报道的实验模型的蛋白质和水的可及性所观察到的分子动力学模拟。这些数据支持提出的CD3 xi肽结构，并且模拟指出水和脂质头基的结构紊乱是不均匀加宽的主要来源。两者合计，这种严格的分析膜肽的振动动力学提供了实验洞察到一个时间制度的运动，到目前为止，在很大程度上尚未探索。
Fast protein dynamics can be missed with techniques that have relatively slow observation times. Using 2D IR spectroscopy and isotope labeling, we have probed the rapid, picosecond dynamics of a membrane protein in its native environment. By measuring the homogeneous and inhomogeneous IR linewidths of 11 amide 1 modes (backbone carbonyl stretch), we have captured the structural distributions and dynamics of the CD3 xi protein along its transmembrane segment that are lost with slower time-scale techniques. We find that the homogeneous lifetimes and population relaxation times are the same for almost all of the residues. In contrast, the inhomogeneous linewidths vary significantly with the largest inhomogeneous distribution occurring for residues near the N terminus and the narrowest near the center. This behavior is highly consistent with a recently reported experimental model of the protein and water accessibility as observed by molecular dynamics simulations. The data support the proposed CD3 xi peptide structure, and the simulations point to the structural disorder of water and lipid head-groups as the main source of inhomogeneous broadening. Taken together, this rigorous analysis of the vibrational dynamics of a membrane peptide provides experimental insight into a time regime of motions that has so far been largely unexplored.