Connelly P R, Varadarajan R, Sturtevant J M, Richards F M
Department of Chemistry, Yale University, New Haven, Connecticut 06511.
Biochemistry. 1990 Jun 26;29(25):6108-14. doi: 10.1021/bi00477a031.
Two fragments of pancreatic ribonuclease A, a truncated version of S-peptide (residues 1-15) and S-protein (residues 21-124), combine to give a catalytically active complex designated ribonuclease S. Residue 13 in the peptide is methionine. According to the X-ray structure of the complex of S-protein and S-peptide (1-20), this residue is almost fully buried. We have substituted Met-13 with seven other hydrophobic residues ranging in size from glycine to phenylalanine and have determined the thermodynamic parameters associated with the binding of these analogues to S-protein by titration calorimetry at 25 degrees C. These data should provide useful quantitative information for evaluating the contribution of hydrophobic interactions in the stabilization of protein structures.
胰腺核糖核酸酶A的两个片段，即截短的S肽（1 - 15位残基）和S蛋白（21 - 124位残基），结合形成一个具有催化活性的复合物，称为核糖核酸酶S。该肽中的第13位残基是甲硫氨酸。根据S蛋白与S肽（1 - 20）复合物的X射线结构，此残基几乎完全被掩埋。我们用从甘氨酸到苯丙氨酸大小不等的其他七个疏水残基取代了甲硫氨酸13，并通过25℃下的滴定热分析法测定了这些类似物与S蛋白结合的热力学参数。这些数据应为评估疏水相互作用在蛋白质结构稳定中的作用提供有用的定量信息。
