Arakawa T, Goddette D
Arch Biochem Biophys. 1985 Jul;240(1):21-32. doi: 10.1016/0003-9861(85)90004-9.
This paper describes a theory for the mechanism of three-state transition of proteins which is often observed in aqueous organic cosolvent systems, i.e., from the native, via intermediate to helical forms. The first transition, accompanied by changes in the tertiary and/or secondary structures, was explained by larger bindings of the organic solvent molecules to the intermediate than to the native state; the second transition, resulting in changes mainly in the secondary structure, i.e., helical transition, was explained by less hydration sites for the helical state. Computer simulations of the transition were carried out using plausible values for the number of alcohol and water binding sites of proteins as well as for the equilibrium constant of the transitions in the absence of cosolvent. A reasonable agreement with the experimental transitions was observed. The stronger effect of alcohols with longer alkyl chains was explained by their greater binding to nonpolar groups and their larger exclusion from peptide groups.
本文描述了一种蛋白质三态转变机制的理论，这种转变在水性有机助溶剂体系中经常观察到，即从天然态，经中间态转变为螺旋态。第一次转变伴随着三级和/或二级结构的变化，其解释是有机溶剂分子与中间态的结合比与天然态的结合更强；第二次转变主要导致二级结构的变化，即螺旋转变，其解释是螺旋态的水化位点较少。利用蛋白质中醇和水结合位点的合理数量值以及在没有助溶剂时转变的平衡常数，对转变进行了计算机模拟。观察到与实验转变有合理的一致性。烷基链较长的醇具有更强的效应，这是因为它们与非极性基团的结合更强，并且从肽基团中被排斥的程度更大。
