MODEL-FREE APPROACH TO THE INTERPRETATION OF NUCLEAR MAGNETIC-RESONANCE RELAXATION IN MACROMOLECULES .2. ANALYSIS OF EXPERIMENTAL RESULTS
MODEL-FREE APPROACH TO THE INTERPRETATION OF NUCLEAR MAGNETIC-RESONANCE RELAXATION IN MACROMOLECULES .2. ANALYSIS OF EXPERIMENTAL RESULTS
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DOI：
10.1021/ja00381a010
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发表时间：
1982-01-01
影响因子：
15
通讯作者：
SZABO, A
中科院分区：
文献类型：
--
作者：
LIPARI, G;SZABO, A
溶液中大分子的NMR弛豫实验中快速内部运动的唯一动力学信息由广义序参数S和有效相关时间τ e指定。本文讨论了这些信息的提取和解释。描述了用于通过使用最小二乘法和在某些有利的情况下通过使用分析公式从实验数据获得S2和τ 2的过程。各种实验，然后进行分析，以产生信息的时间尺度和空间限制的内部运动的异亮氨酸在肌球蛋白，蛋氨酸在二氢叶酸还原酶和肌红蛋白，一些脂肪族残基在基本的胰蛋白酶抑制剂，和乙基异氰化物绑定到肌红蛋白，血红蛋白和脂肪族侧链在3个无规卷曲聚合物。S2和τ e的数值可以在各种模型的框架内容易地解释。用这种方法，人们可以得到与用复杂的谱密度拟合数据所得到的内部运动的物理图象相同的内部运动的物理图象。与有效相关时间τ e不同，序参数的数值在确定什么模型可以用于描述实验中起着至关重要的作用;排除了序参数不能再现的模型。相反，任何能够产生正确S值的模型都是有效的。
Unique dynamic information on fast internal motions in an NMR relaxation experiment on macromolecules in solution is specified by a generalized order parameter, S, and an effective correlation time, .tau.e. This paper deals with the extraction and interpretation of this information. The procedure used to obtain S2 and .tau.2 from experimental data by using a least-squares method and, in certain favorable circumstances, by using an analytical formula is described. A variety of experiments are then analyzed to yield information on the time scale and spatial restriction of internal motions of isoleucines in myoglobulin, methionines in dihydrofolate reductase and myoglobin, a number of aliphatic residues in basic pancreatic trypsin inhibitor, and ethyl isocyanide bound to myoglobin, Hb, and aliphatic side chains in 3 random-coil polymers. The numerical values of S2 and .tau.e can be readily interpreted within the framework of a variety of models. In this way, one can obtain the same physical picture of internal motions as that obtained by using complicated spectral densities to fit the data. The numerical value of the order parameter, unlike the effective correlation time .tau.e, plays a crucial role in determining what models can be used to describe the experiment; models in which the order parameter cannot be reproduced are eliminated. Conversely, any model that can yield the correct value of S works.