Merlino Antonello, Pontillo Nicola, Graziano Giuseppe
Dipartimento di Scienze Chimiche, Università degli Studi di Napoli Federico II, Complesso Universitario di Monte Sant'Angelo, Via Cintia, 80126 Napoli, Italy.
Dipartimento di Scienze e Tecnologie, Università del Sannio, Via Port'Arsa 11, 82100 Benevento, Italy.
Phys Chem Chem Phys. 2016 Dec 21;19(1):751-756. doi: 10.1039/c6cp07397b.
Experimental measurements and computational results have shown that polypeptide chains, made up of 15-25 glycine residues, collapse to compact structures in water at room temperature. This contrasts with the classic idea that the burial of nonpolar side chains, i.e., the hydrophobic effect, is the driving force of collapse and folding of polypeptides and proteins. It is thus necessary to find a different driving force for polyglycine collapse. The present study aims at showing that the hydrophobic effect has to be re-defined in terms of decrease in solvent-excluded volume associated with chain collapse so that it is characterized by a gain in translational entropy of water molecules. This indicates that the presence of nonpolar side chains is not so important for polypeptide and protein collapse, even though it may be fundamental for the attainment of a unique folded structure.
实验测量和计算结果表明，由15至25个甘氨酸残基组成的多肽链在室温下于水中会折叠成紧密结构。这与经典观点形成对比，即非极性侧链的埋藏，也就是疏水效应，是多肽和蛋白质折叠和塌缩的驱动力。因此，有必要为聚甘氨酸塌缩寻找一种不同的驱动力。本研究旨在表明，疏水效应必须根据与链塌缩相关的溶剂排除体积的减小来重新定义，这样它就以水分子平动熵的增加为特征。这表明非极性侧链的存在对于多肽和蛋白质的塌缩并非那么重要，尽管它对于获得独特的折叠结构可能至关重要。
