Berger J S, Ernst J A, Nicoletta A C, Hull L A, Yang J, Qiu R, Morozov V N, Kallenbach N R
Department of Chemistry, Union College, Schenectady, NY 12308, USA.
J Biomol Struct Dyn. 1996 Dec;14(3):285-91. doi: 10.1080/07391102.1996.10508124.
Whether or not surface salt bridges have a strong stabilizing effect on the native structure in proteins remains uncertain. Previous studies of model peptides have shown that salt bridges spaced at i,i +4 along the chain are more stabilizing than those spaced at i,i +3, with a preference for the order acid-base rather than base-acid from N to C terminus. An analysis of the effect of spacing the ion pairs in short helical peptides is presented, in which acidic and basic side chains spaced two or three residues apart alternate along the chain. The mixed spacing proves to be stabilizing relative to pure spacings. A control peptide in which salt bridges were spaced uniformly three residues apart proved to form a beta-sheet structure rather than alpha-helix. This is due to formation of a silk-like apolar face consisting of alanine side chains; the mesoscopic structure formed by these sheets can be imaged by scanning microscopy.
蛋白质中表面盐桥对天然结构是否具有强大的稳定作用仍不确定。先前对模型肽的研究表明，沿链在i，i +4位置间隔的盐桥比在i，i +3位置间隔的盐桥更具稳定性，从N端到C端更倾向于酸碱顺序而非碱酸顺序。本文对短螺旋肽中离子对间距的影响进行了分析，其中酸性和碱性侧链沿链交替间隔两个或三个残基。相对于纯间距，混合间距被证明具有稳定性。一个盐桥均匀间隔三个残基的对照肽被证明形成了β-折叠结构而非α-螺旋结构。这是由于形成了由丙氨酸侧链组成的类似丝绸的非极性面；这些薄片形成的介观结构可以通过扫描显微镜成像。
