CONFORMATION OF CYCLIC PEPTIDES .10. CONFORMATIONAL AVERAGING IN PEPTIDES WITH SEQUENCE CYCLO-(GLY-D-XXX-L-YYY)2
CONFORMATION OF CYCLIC PEPTIDES .10. CONFORMATIONAL AVERAGING IN PEPTIDES WITH SEQUENCE CYCLO-(GLY-D-XXX-L-YYY)2
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DOI：
10.1021/ja00481a046
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发表时间：
1978-01-01
影响因子：
15
通讯作者：
SCHAMPER, TJ
中科院分区：
文献类型：
--
作者：
KOPPLE, KD;GO, A;SCHAMPER, TJ
圆二色性测量支持的NMR研究表明，甲醇中的环-（Gly-D-Val-L-Leu）2和水中的环-（Gly-D-Val-L-Leu-Gly-D-Orn-L-Orn）和环-（Gly-D-Phe-Gly-D-Orn-L-Orn）有利于具有连接L-Xxx-Gly转角的扩展D-系列残基的骨架构象。对于甲醇中的环（Gly-D-Leu-L-Leu）2，单一骨架构象的证据并不明显，对于二甲基亚砜中的任何肽也是如此，并且建议两种或多种骨架构象类型之间快速交换。在这些情况下，N-H质子化学位移的温度系数是溶剂暴露的不可靠指南。提出了一种相关肽环-（Gly-D-Val-L-Leu-L-Ala-D-His-L-His）的构象。描述了肽的合成。
NMR studies, supported by circular dichroism measurements, indicate that cyclo-(Gly-D-Val-L-Leu)2 in methanol, and cyclo-(Gly-D-Val-L-Leu-Gly-D-Orn-L-Orn) and cyclo-(Gly-D-Phe-Gly-D-Orn-L-Orn) in water favor a backbone conformation with extended D-series residues connecting L-Xxx-Gly turns. Evidence for a single backbone conformation is not apparent for cyclo(Gly-D-Leu-L-Leu)2 in methanol, nor is it for any of the peptides in dimethyl sulfoxide, and rapid exchange among two or more backbone conformation types is suggested. The temperature coefficient of N-H proton chemical shift is an unreliable guide to solvent exposure in these cases. A conformation is proposed for a related peptide, cyclo-(Gly-D-Val-L-Leu-L-Ala-D-His-L-His). Synthesis of the peptides is described.