文章基本信息

标题：Conformational Interconversions of the Cyclic Hexapeptide Cyclo(Pro-Gly)3
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作者：Charles M. Deber ; Dennis A. Torchia ; Simon C. K. Wong 等
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1972
卷号：69
期号：7
页码：1825-1829
DOI：10.1073/pnas.69.7.1825
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：A cyclic hexapeptide, cyclo(Pro-Gly-Pro-Gly-Pro-Gly), has been synthesized; its solution conformations were examined by 220-MHz nuclear magnetic resonance spectroscopy. The solution structures have been deduced, and shown to vary as a function of solvent polarity. In addition, it has been found that this cyclic peptide binds alkali metal cations. While the predominant conformation of this cyclic peptide is 3-fold symmetric in the apolar solvent methylene chloride, an asymmetric structure is preferred in some polar solvents (water, dimethylsulfoxide). However, addition of alkali metal salts, such as sodium thiocyanate, to dimethylsulfoxide solutions of the peptide shifts the conformational equilibrium in favor of a second type of C3-symmetric structure, presumably the result of the formation of a stable peptide-metal ion complex. Nuclear magnetic resonance data suggest that the peptide in methylene chloride solution takes up a conformation containing three cis' Pro C[α]-C=O bonds and three cis Gly-Pro peptide bonds; that water and dimethylsulfoxide stabilize a conformer in which one (or two) sets of such bonds of a given Pro-Gly unit have undergone interconversion to trans'/trans forms; and that alkali metal cations complex the cyclic peptide in a C3-symmetric all-trans'/trans structure.
关键词：peptides ; NMR ; alkali metal complexes