Rogers N K, Sternberg M J
J Mol Biol. 1984 Apr 15;174(3):527-42. doi: 10.1016/0022-2836(84)90334-6.
The alpha-helix has an electric dipole arising from the alignment of peptide dipoles parallel to the helix axis. The effect of this alpha-helix dipole in the stabilization of the tertiary structure of globular proteins is examined using three of the commonly used dielectric models. These models are; (1) the uniform dielectric model, (2) the distance dependent dielectric model and (3) the cavity dielectric model. Of these the cavity model is the most reasonable since it attempts to describe the markedly different dielectric responses of the solvent and the protein. The protein is set at a low continuous dielectric value and the solvent is set at a high continuous dielectric value. It is found that for the cavity model of the dielectric the calculated interaction energy between two helices is strongly dependent upon how exposed the helix termini are to solvent. For helices with exposed termini the calculations using the cavity model yield electrostatic interaction energies which are lower by an order of magnitude than those obtained using the uniform dielectric model.
α-螺旋具有由平行于螺旋轴排列的肽偶极产生的电偶极。使用三种常用的介电模型研究了这种α-螺旋偶极在球状蛋白质三级结构稳定中的作用。这些模型是：（1）均匀介电模型，（2）距离依赖性介电模型和（3）腔介电模型。其中，腔模型最为合理，因为它试图描述溶剂和蛋白质明显不同的介电响应。将蛋白质设置为低连续介电值，将溶剂设置为高连续介电值。发现对于介电的腔模型，两个螺旋之间计算出的相互作用能强烈依赖于螺旋末端对溶剂的暴露程度。对于末端暴露的螺旋，使用腔模型的计算得出的静电相互作用能比使用均匀介电模型获得的静电相互作用能低一个数量级。
