Solid model compounds and the thermodynamics of protein unfolding.
Solid model compounds and the thermodynamics of protein unfolding.
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固体模型化合物和蛋白质展开的热力学。
DOI：
10.1016/0022-2836(91)90506-2
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发表时间：
1991
影响因子：
5.6
通讯作者：
Gill,SJ
中科院分区：
文献类型：
--
作者：
Murphy,KP;Gill,SJ
根据基团可加性对固体环二肽溶解到水中的热力学数据进行分析，为小球状蛋白变性和模型化合物溶解到水中所观察到的焓和熵收敛温度提供了理论依据。收敛温度是一系列相关化合物的外推焓或熵变化呈现共同值的温度。在这些温度下（T H∗和T S∗），对应的热力学值（ΔH°和ΔS°）的极性贡献为零。然后可以评估其他贡献，如氢键和构型效应，并评估它们对球状蛋白稳定性的定量影响。结果表明，与先前的结果一致，变性热容由极性基团暴露的较大正贡献和极性基团暴露的显著负贡献组成。大的极性贡献表明疏水效应的液态烃模型不能准确地表示极性对ΔH°变性的贡献。相反，人们发现肽基（氢键）对焓稳定的贡献很大。将球状蛋白质的平均结构特征（即残基数、埋极性基团的分数和氢键的分数）与它们的特定基团贡献相结合，可以对蛋白质的热力学性质进行一级预测。预测值与文献中细胞色素c、肌红蛋白、核糖核酸酶A和溶菌酶的预测值比较好。主要的热力学特征是由给定蛋白质中肽和极性基团的数量来描述的。
Abstract Analysis of thermodynamic data on the dissolution of solid cyclic dipeptides into water in terms of group additivity provides a rationale for the enthalpy and entropy convergence temperatures observed for small globular protein denaturation and the dissolution of model compounds into water. Convergence temperatures are temperatures at which the extrapolated enthalpy or entropy changes for a series of related compounds take on a common value. At these temperatures (T H∗ and T S∗) the apolar contributions to the corresponding thermodynamic values (ΔH° and ΔS°) are shown to be zero. Other contributions such as hydrogen bonding and configurational effects can then be evaluated and their quantitative effects on the stability of globular proteins assessed. It is shown that the denaturational heat capacity is composed of a large positive contribution from the exposure of apolar groups and a significant negative contribution from the exposure of polar groups in agreement with previous results. The large apolar contribution suggests that a liquid hydrocarbon model of the hydrophobic effect does not accurately represent the apolar contribution to ΔH° of denaturation. Rather, significant enthalpic stabilizing contributions are found to arise from peptide groups (hydrogen bonding). Combining the average structural features of globular proteins (ie number of residues, fraction of buried apolar groups and fraction of hydrogen bonds) with their specific group contributions permits a first-order prediction of the thermodynamic properties of proteins. The predicted values compare well with literature values for cytochrome c, myoglobin, ribonuclease A and lysozyme. The major thermodynamic features are described by the number of peptide and apolar groups in a given protein.