Quantitative analysis of backbone dynamics in a crystalline protein from nitrogen-15 spin-lattice relaxation
Quantitative analysis of backbone dynamics in a crystalline protein from nitrogen-15 spin-lattice relaxation
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DOI：
10.1021/ja055182h
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发表时间：
2005-12-28
影响因子：
15
通讯作者：
Emsley, L
中科院分区：
文献类型：
--
作者：
Giraud, N;Blackledge, M;Emsley, L
详细分析了氮-15在微晶蛋白质的纵向弛豫时间。根据运动幅度和特征时间尺度，建立了弛豫时间的定量解释理论模型。不同的平均方案进行检查，以提出一个分析的松弛曲线，考虑到MAS实验的特异性。特别是，它示出，魔角旋转平均松弛率经历了一个转子周期内的单次旋转，导致在个别的松弛曲线，是依赖于其相应的转盘相对于转子轴线的方向。因此，粉末平均导致观察到的衰减曲线的非指数行为。我们从实验衰减曲线中提取动态信息，使用锥模型中的扩散。我们应用这项研究的微晶蛋白质Crh在两个不同的领域的自旋-晶格弛豫速率的分析，并确定差分动力学参数的几个残基的蛋白质。
A detailed analysis of nitrogen-15 longitudinal relaxation times in microcrystalline proteins is presented. A theoretical model to quantitatively interpret relaxation times is developed in terms of motional amplitude and characteristic time scale. Different averaging schemes are examined in order to propose an analysis of relaxation curves that takes into account the specificity of MAS experiments. In particular, it is shown that magic angle spinning averages the relaxation rate experienced by a single spin over one rotor period, resulting in individual relaxation curves that are dependent on the orientation of their corresponding carousel with respect to the rotor axis. Powder averaging thus leads to a nonexponential behavior in the observed decay curves. We extract dynamic information from experimental decay curves, using a diffusion in a cone model. We apply this study to the analysis of spin-lattice relaxation rates of the microcrystalline protein Crh at two different fields and determine differential dynamic parameters for several residues in the protein.