Spectroscopic investigations on model cyclic peptides containing beta-amino acids

摘要

The continuously growing interest in the design of biologically active peptides led to the development of molecular tools capable of inducing a required three-dimensional structure in conformationally flexible peptides.The properties of peptides strongly depend on their folded conformation,from which beta-and gamma-turns are two important groups of regular/ordered secondary structures.Characterization of turns is usually achieved by combined FTIR and CD spectroscopic studies,however,spectroscopic detection of gamma-turns and their distinction from beta-turns is often difficult.This shows the importance of studies on model compounds known to preferentially adopt gamma-turns,such as small cyclic peptides containing beta-amino acids.Recently,vibrational circular dichroism(VCD)is one of the most promising spectroscopic techniques in the conformational analysis of peptides and proteins.This work reports systematic FTIR,VCD and CD spectroscopic studies on gamma-turn model cyclic tetrapeptides cyclo(beta-Ala-Ala-beta-Ala-Pro),cyclo(beta-Ala-Ala-beta-Ala-Pro)and cyclo(beta-homo-Ala-Pro-Phe-Gly).