CONTRIBUTION TO THE THERMODYNAMICS OF PROTEIN FOLDING FROM THE REDUCTION IN WATER-ACCESSIBLE NONPOLAR SURFACE-AREA
CONTRIBUTION TO THE THERMODYNAMICS OF PROTEIN FOLDING FROM THE REDUCTION IN WATER-ACCESSIBLE NONPOLAR SURFACE-AREA
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DOI：
10.1021/bi00231a019
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发表时间：
1991-04-30
期刊：
影响因子：
2.9
通讯作者：
RECORD, MT
中科院分区：
文献类型：
--
作者：
LIVINGSTONE, JR;SPOLAR, RS;RECORD, MT
蛋白质折叠和碳氢化合物从稀水溶液到纯液相的转移在热力学上是相似的，因为这两个过程都从水中去除了非极性表面，并且都伴随着非常大的负热容变化。基于一组有限的公开的表面积，我们先前提出，用于烃从水转移到纯液相和用于球状蛋白质折叠的热容变化（Δ-C（p）度）与水可接近的非极性表面积（Δ-A（np））的减少呈现相同的比例[Spolar，R.美国，哈，J.H.，& Record，M. T.，Jr.等人（1989）Proc. Acad. Sci. U.S.A.86，8382-8385]。这一建议的结果是，蛋白质折叠的实验Δ C（p）度可以用来获得Δ A（np）的估计值，以及从水中去除非极性表面对折叠状态稳定性的贡献。本文采用严格的分子表面积算法[里士满，T. J.（1984）J. Mol. Biol.178，63-89]，以获得整组球状蛋白质的天然和完全变性状态的水可及非极性表面积的自洽值，对于所述整组球状蛋白质，晶体结构和Δ-C（p）折叠度均已确定，对于所述整组液态烃和可液化烃，Δ-C（p）转移度已知。这两个过程（碳氢化合物转移和蛋白质折叠）在Δ C（p）度和Δ A（np）之间表现出相同的正比例关系。我们的结论是，在蛋白质折叠和其他涉及蛋白质的自组装过程中观察到的大的负热容变化提供了一个定量的措施，减少水可及的非极性表面积和疏水效应的贡献的稳定性的天然状态和蛋白质组装。
Protein folding and the transfer of hydrocarbons from a dilute aqueous solution to the pure liquid phase are thermodynamically similar in that both processes remove nonpolar surface from water and both are accompanied by anomalously large negative heat capacity changes. On the basis of a limited set of published surface areas, we previously proposed that heat capacity changes (DELTA-C(p)degrees) for the transfer of hydrocarbons from water to the pure liquid phase and for the folding of globular proteins exhibit the same proportionality to the reduction in water-accessible nonpolar surface area (DELTA-A(np)) [Spolar, R. S., Ha, J. H., & Record, M. T., Jr. (1989) Proc. Natl. Acad. Sci. U.S.A. 86, 8382-8385]. The consequence of this proposal is that the experimental DELTA-C(p)degrees for protein folding can be used to obtain estimates of DELTA-A(np) and of the contribution to the stability of the folded state from removal of a nonpolar surface from water. In this paper, a rigorous molecular surface area algorithm [Richmond, T. J. (1984) J. Mol. Biol. 178, 63-89] is applied to obtain self-consistent values of the water-accessible nonpolar surface areas of the native and completely denatured states of the entire set of globular proteins for which both crystal structures and DELTA-C(p)degrees of folding have been determined and for the set of liquid and liquefiable hydrocarbons for which DELTA-C(p)degrees of transfer are known. Both processes (hydrocarbon transfer and protein folding) exhibit the same direct proportionality between DELTA-C(p)degrees and DELTA-A(np). We conclude that the large negative heat capacity changes observed in protein folding and other self-assembly processes involving proteins provide a quantitative measure of the reduction in the water-accessible nonpolar surface area and of the contribution of the hydrophobic effect to the stability of the native state and to protein assembly.