2. NMR and conformational analysis indicated that both of these analogues favor the same backbone conformation as 2, whereas similar analysis of less potent analogues indicates that an altered backbone conformation is favored. The conformational analysis showed that steric repulsion by a 1,3-allylic strain-like effect across the planar peptide bond might contribute to the conformational preferences
以前,我们已经确定了高效CXCR4拮抗剂2 [cyclo(-D-Tyr1-Arg2-Arg3-Nal4-Gly5-)]及其Arg2差向异构体3 [cyclo(-D-Tyr1-D-Arg2-Arg3-Nal4- (Gly5-)]通过筛选基于五残基CXCR4拮抗剂1的结构-活性关系研究而设计的环状五肽文库。在本研究中,合成了一系列新的类似物2和3,以评估肽侧链和骨架修饰对
生物活性的影响。根据Ala扫描研究,其中2和3中的每个残基都被具有相同手性的Ala取代,用Ala取代Arg3和Nal4 [Nal = L-3-(2-
萘基)丙
氨酸](化合物6, 7,10,11)导致效力显着降低,表明这些
氨基酸是
生物活性的重要贡献者。对于环状肽主链,进行了几种修饰,包括在Gly5位置的d / I-Ala或环状
氨基酸取代以及酰胺氮上的连续N-甲基化。在类似物中,化合物13 [环(-D-Tyr1-Arg2-Arg3-Nal4-D-Ala5-)]和32