CONTRIBUTION OF HYDROGEN-BONDING TO THE CONFORMATIONAL STABILITY OF RIBONUCLEASE-T1
CONTRIBUTION OF HYDROGEN-BONDING TO THE CONFORMATIONAL STABILITY OF RIBONUCLEASE-T1
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DOI：
10.1021/bi00118a013
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发表时间：
1992-01-28
期刊：
影响因子：
2.9
通讯作者：
PACE, CN
中科院分区：
文献类型：
--
作者：
SHIRLEY, BA;STANSSENS, P;PACE, CN
30年来，流行的观点认为疏水效应比氢键对球状蛋白质构象稳定性的贡献要大得多。本文的结果和推论表明，氢键和疏水效应对核糖核酸酶T1(RNaseT1)的构象稳定性有类似的贡献。当RNaseT1折叠时，形成了86个平均长度为2.95埃的分子内氢键。RNaseT1[Tyr-->；Phe(5)，Ser-->；Ala(3)，Asn-->；Ala(4)]共制备了12个突变体，共去除了17个氢键，平均长度为2.93埃。在尿素和热展开研究的基础上，这些突变体的构象稳定性因氢键而平均下降1.3千卡/摩尔。这一估计与几个相关系统的结果符合得很好。因此，我们估计氢键对RNaseT1的构象稳定性的贡献约为110kcal/mol，这与疏水效应的贡献相当。接受分子内氢键对体系在水环境中稳定性的贡献为1.3+/-0.6千卡/摩尔的观点，使我们更容易理解蛋白质“熔融球状”状态的稳定性，以及小肽的a-螺旋构象。
For 30 years, the prevailing view has been that the hydrophobic effect contributes considerably more than hydrogen bonding to the conformational stability of globular proteins. The results and reasoning presented here suggest that hydrogen bonding and the hydrophobic effect make comparable contributions to the conformational stability of ribonuclease T1 (RNase T1). When RNase T1 folds, 86 intramolecular hydrogen bonds with an average length of 2.95 angstrom are formed. Twelve mutants of RNase T1 [Tyr --> Phe (5), Ser --> Ala (3), and Asn --> Ala (4)] have been prepared that remove 17 of the hydrogen bonds with an average length of 2.93 angstrom. On the basis of urea and thermal unfolding studies of these mutants, the average decrease in conformational stability due to hydrogen bonding is 1.3 kcal/mol per hydrogen bond. This estimate is in good agreement with results from several related systems. Thus, we estimate that hydrogen bonding contributes about 110 kcal/mol to the conformational stability of RNase T1 and that this is comparable to the contribution of the hydrophobic effect. Accepting the idea that intramolecular hydrogen bonds contribute 1.3 +/- 0.6 kcal/mol to the stability of systems in an aqueous environment makes it easier to understand the stability of the "molten globule' states of proteins, and the a-helical conformations of small peptides.