In order to investigate the structure-activity relationship of the “gratisin”-related peptide, cyclo(–Val–Orn–Leu–d-Phe–Pro–d-Tyr–)2 (GR-I), its two analogs, cyclo(–Val–Orn–Leu–d-Ala–Pro–d-Tyr–)2 (6a) and cyclo(–Val–Orn–Leu–d-Phe–Pro–d-Ala–)2 (6b), were synthesized. The CD spectra of these synthetic peptides in an aqueous solution were similar to that of GR-I, indicating that these peptides have similar conformations in an aqueous solution. The activity of 6b was half that of GR-I, whereas 6a did not show any antibiotic activity. These results indicated that the phenyl group of the d-Phe residue preceding the Pro residue is essential for exhibiting the activity, while the p-hydroxyphenyl group of the d-Tyr residue following the Pro residue is not essential.
为了研究 "gratisin "相关
多肽环(-Val-Orn-Leu-d-Phe-Pro-d-Tyr-)2(GR-I)的结构-活性关系,合成了其两个类似物环(-Val-Orn-Leu-d-Ala-Pro-d-Tyr-)2 (6a)和环(-Val-Orn-Leu-d-Phe-Pro-d-Ala-)2 (6b)。这些合成肽在
水溶液中的 CD 光谱与 GR-I 相似,表明这些肽在
水溶液中具有相似的构象。6b 的活性是 GR-I 的一半,而 6a 则没有显示出任何
抗生素活性。这些结果表明,Pro残基之前的d-Phe残基的
苯基是显示活性的必要条件,而Pro残基之后的d-Tyr残基的对羟基
苯基则不是必要条件。