期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2013
卷号：110
期号：5
页码：1670-1673
DOI：10.1073/pnas.1220825110
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The hydrophobic free energy in current use is based on transfer of alkane solutes from liquid alkanes to water, and it has been argued recently that these values are incorrect and should be based instead on gas-liquid transfer data. Hydrophobic free energy is measured here by gas-liquid transfer of hydrocarbon gases from vapor to water. The new definition reduces more than twofold the values of the apparent hydrophobic free energy. Nevertheless, the newly defined hydrophobic free energy is still the dominant factor that drives protein folding as judged by {Delta}Cp, the change in heat capacity, found from the free energy change for heat-induced protein unfolding. The {Delta}Cp for protein unfolding agrees with {Delta}Cp values for solvating hydrocarbon gases and disagrees with {Delta}Cp for breaking peptide hydrogen bonds, which has the opposite sign. The {Delta}Cp values for the enthalpy of liquid-liquid and gas-liquid transfer are similar. The plot of free energy against the apparent solvent-exposed surface area is given for linear alkanes, but only for a single conformation, the extended conformation, of these flexible-chain molecules. The ability of the gas-liquid hydrophobic factor to predict protein stability is tested and reasonable agreement is found, using published data for the dependences on temperature of the unfolding enthalpy of ribonuclease T1 and the solvation enthalpies of the nonpolar and polar groups.
关键词：folding energetics ; reference solvent ; osmolytes ; cavity work
