EXTRACTING HYDROPHOBIC FREE-ENERGIES FROM EXPERIMENTAL-DATA - RELATIONSHIP TO PROTEIN FOLDING AND THEORETICAL-MODELS
EXTRACTING HYDROPHOBIC FREE-ENERGIES FROM EXPERIMENTAL-DATA - RELATIONSHIP TO PROTEIN FOLDING AND THEORETICAL-MODELS
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DOI：
10.1021/bi00104a017
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发表时间：
1991-10-08
期刊：
影响因子：
2.9
通讯作者：
HONIG, B
中科院分区：
文献类型：
--
作者：
SHARP, KA;NICHOLLS, A;HONIG, B
通常认为碳氢化合物在水中的溶解度和蒸气压测量可以提供 20-30 卡/（摩尔埃 2）范围内疏水效应强度的估计。 我们根据溶液热力学的新发展对溶解度数据进行重新评估，表明烃溶质的疏水表面自由能为 46-47 cal/(mol. angstrom 2)，尽管实际值很大程度上取决于曲率效应 [Nicholls 等人。 （1991）蛋白质（正在出版）；夏普等人。 (1991) 科学 252, 106-109]。 支持疏水效应估计值如此显着增加的论据部分源于理论考虑，部分源于 De Young 和 Dill 的实验结果 [(1990) J. Phys.化学。 94, 801-809]关于苯在水和烷烃溶剂之间的分配。 先前对疏水效应的估计来自对溶质分配数据的分析，该分析并未完全考虑体积熵的变化。 我们在这里展示了理想气体方程如何与实验摩尔体积相结合来解释这种变化。 基于环己烷到水和辛醇到水的转移能量，推导了 20 种氨基酸的修订溶解度标度。 这些尺度（特别是辛醇尺度）与 Kellis 等人的突变蛋白稳定性测量值之间的一致性。 [(1989) 生物化学 28, 4914-4922] 和 Shortle 等人。 [(1990)生物化学29, 8033-8041]很好。 疏水相互作用强度的增加对蛋白质折叠、底物结合、核酸碱基堆积的能量学以及计算机模拟的解释具有影响。
Solubility and vapor pressure measurements of hydrocarbons in water are generally thought to provide estimates of the strength of the hydrophobic effect in the range 20-30 cal/(mol. angstrom 2). Our reassessment of the solubility data on the basis of new developments in solution thermodynamics suggests that the hydrophobic surface free energy for hydrocarbon solutes is 46-47 cal/(mol. angstrom 2), although the actual value depends strongly on curvature effects [Nicholls et al. (1991) Proteins (in press); Sharp et al. (1991) Science 252, 106-109]. The arguments to support such a significant increase in the estimate of the hydrophobic effect stem partly from theoretical considerations and partly from the experimental results of De Young and Dill [(1990) J. Phys. Chem. 94, 801-809] on benzene partition between water and alkane solvents. Previous estimates of the hydrophobic effect derive from an analysis of solute partition data, which does not fully account for changes in volume entropy. We show here how the ideal gas equations, combined with experimental molar volumes, can account for such changes. Revised solubility scales for the 20 amino acids, based on cyclohexane to water and octanol to water transfer energies, are derived. The agreement between these scales, particularly the octanol scale, and mutant protein stability measurements from Kellis et al. [(1989) Biochemistry 28, 4914-4922] and Shortle et al. [(1990) Biochemistry 29, 8033-8041] is good. The increased strength of the hydrophobic interaction has implications for the energetics of protein folding, substrate binding, and nucleic acid base stacking and the interpretation of computer simulations.