A series of cyclic peptides varying in ring size and in amino acid constituents was synthesized. Cyclization reactions of linear peptides were carried out by the azide, p-nitrophenyl ester, N-hydroxysuccinimide ester and diethyl phosphorocyanidate methods. Intermolecular cyclodimerization was also applied for the preparation of a cyclic hexapeptide. The reaction yield in each cyclization method was found to be sufficient for preparative purposes. Conformational analysis of the cyclic peptides was carried out by using proton nuclear magnetic resonance. The temperature dependency of peptide NH signals revealed that hexapeptides with the cyclo(-Gly-Xxx-Gly-)2 sequence are stabilized by intramolecular hydrogen bonding and are resistant to temperatureinduced conformational change.
合成了一系列环状肽,具有不同的环大小和
氨基酸成分。通过
叠氮化物、对
硝基苯基酯、N-羟基琥珀
酰亚胺酯和
二乙基磷氰酸盐法对线性肽进行环化反应。还应用了分子间环二聚化法制备环状六肽。每种环化方法的反应产率均被发现足够用于制备目的。使用质子核磁共振对环状肽进行了构象分析。肽NH信号的温度依赖性表明,具有环状(-Gly-Xxx-Gly-)2序列的六肽通过分子内氢键得到稳定,并且对温度诱导的构象变化具有抗性。