CONTRIBUTION OF HYDRATION TO PROTEIN-FOLDING THERMODYNAMICS .2. THE ENTROPY AND GIBBS ENERGY OF HYDRATION
CONTRIBUTION OF HYDRATION TO PROTEIN-FOLDING THERMODYNAMICS .2. THE ENTROPY AND GIBBS ENERGY OF HYDRATION
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DOI：
10.1006/jmbi.1993.1417
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发表时间：
1993-07-20
影响因子：
5.6
通讯作者：
MAKHATADZE, GI
中科院分区：
文献类型：
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作者：
PRIVALOV, PL;MAKHATADZE, GI
在5至125°C的温度范围内，利用这些蛋白质在天然和未折叠状态下暴露于水的基团的结构信息以及各种模型化合物从气相转移到水的熵，估计了四种球状蛋白质在蛋白质解折叠时非极性和极性基团的水合熵。后者是使用摩尔标度计算的。结果表明，非极性基团和极性基团的水化熵均为负值，但随温度的升高，水化熵的变化方向不同：极性基团的水化熵的绝对值增大，而非极性基团的水化熵则减小，在122°C时，脂肪族基团的水化熵为零，在104°C时，芳香族基团的水化熵为零，但在较高温度时，水化熵的符号发生变化。通过比较总水合熵和蛋白质去折叠总熵，估算了构象熵。使用先前确定的极性和非极性基团的水合和内部键的破坏，吉布斯自由能的蛋白质基团的水合和破坏的氢键和货车的范德华相互作用已估计。结果表明，极性基团和芳香族非极性基团的水合作用使天然蛋白质结构不稳定，而脂肪族非极性基团的水合作用（疏水水合作用）使其稳定;然而，主要的稳定作用来自内部的货车德瓦尔斯相互作用和氢键。对影响蛋白质折叠构象稳定性的因素分析表明，极性基团的水合作用是蛋白质冷变性的主要原因。
The entropy of hydration of non-polar and polar groups upon protein unfolding has been estimated for four globular proteins in the temperature range 5 to 125°C, using structural information on the groups of these proteins exposed to water in the native and unfolded states and the entropies of transfer of various model compounds from the gaseous phase to water. The latter was calculated using the molar scale. It is shown that the entropies of hydration of non-polar and polar groups are both negative, but change in different directions with increasing temperature: the entropy of hydration of polar groups increases in absolute magnitude, while the entropy of hydration of non-polar groups decreases and becomes zero at 122°C for aliphatic groups and at 104°C for aromatic groups, with a change in sign at higher temperature. The configurational entropy was estimated by comparing the entropy of overall hydration with the total entropy of protein unfolding. Using previously determined enthalpies of hydration of polar and non-polar groups and disruption of the internal bonds, the Gibbs energies of hydration of protein groups and breaking of the hydrogen bonds and van der Waals interactions have been estimated. It was shown that hydration of the polar groups and aromatic non-polar groups destabilizes the native protein structure, while hydration of aliphatic non-polar groups (hydrophobic hydration) stabilizes it; however, the main stabilization effect comes from the internal van der Waals interactions and hydrogen bonding. Analysis of the factors contributing to the stability of the folded protein conformation shows that it is the hydration of polar groups that is mainly responsible for the cold denaturation of proteins.