Tanaka S, Scheraga H A
Macromolecules. 1976 Jan-Feb;9(1):142-59. doi: 10.1021/ma60049a026.
A statistical mechanical (one-dimensional Ising model) treatment, based on the dominance of short-range interactions, is developed in this series of papers; it is intended as an improvement over empirical prediction schemes for obtaining approximate initial conformations of proteins (to be used to try to deduce the native conformation by subsequent energy minimization). In the present paper, the statistical weights for a two-state model (alpha-helical and other conformations) and for a three-state model (alpha-helical, extended, and other conformations) are evaluated from x-ray data on 16 native proteins. The method for evaluating the statistical weights is presented. Asymmetric alpha-helical nucleation parameters are also evaluated for the 20 naturally occurring amino acids. On the basis of these statistical weights, the conformational properties of the twenty naturally occurring amino acids are discussed. The statistical weights evaluated from x-ray data are also discussed in comparison with experimental results on the helix--coil transition in polyamino acids in solution. The predominant role of short-range interactions, and some possible long-range effects in determining the statistical weights, are discussed in conjunction with the mechanism of protein folding.
在这一系列论文中，基于短程相互作用的主导地位，开展了一种统计力学（一维伊辛模型）处理方法；其目的是对用于获取蛋白质近似初始构象（后续通过能量最小化来推导天然构象）的经验预测方案进行改进。在本文中，从16种天然蛋白质的X射线数据评估了二态模型（α螺旋和其他构象）和三态模型（α螺旋、伸展和其他构象）的统计权重。介绍了评估统计权重的方法。还对20种天然存在的氨基酸评估了不对称α螺旋成核参数。基于这些统计权重，讨论了20种天然存在氨基酸的构象性质。还将从X射线数据评估的统计权重与溶液中聚氨基酸螺旋 - 卷曲转变的实验结果进行了比较。结合蛋白质折叠机制，讨论了短程相互作用的主要作用以及在确定统计权重方面一些可能的长程效应。
