Pyrroloisoquinoline-Based Tetrapeptide Analogues Mimicking Reverse-Turn Secondary Structures

摘要

New pyrroloisoquinoline-based tetrapeptides were synthesized in enantiomerically pure form,and their conformational features were studied by NMR,IR,and molecular-modeling techniques.The presence of a reverse turn was observed in both structures,with the C1 stereochemistry playing a central role in determining stable conformations.In particular,all of the analyses led to the conclusion that a type II'beta-turn is mostly stabilized in tetrapeptide mimic 3a,while a typical inverse gamma-turn geometry is revealed for the diastereoisomer 3b.