Aza‐peptides. III. Experimental structural analysis of aza‐alanme and aza‐asparagine‐containing peptides

Publisher Website
Google Scholar
Abstract
To determine the structural perturbations induced by the CαH→Nα exchange in aza‐peptides, we have examined by H NMR and IR spectroscopy various derivatives of the aza‐analogues of alanine, aspartic acid and asparagine in different organic solvents with increasing polarity. Their general formulas are: R'‐AzXaa‐NR2R3, R'‐Pro‐AzXaa‐NR2R3 and R‐AzXaa‐Pro‐NR2R3 (where AzXaa denotes the aza‐analogue of the amino acid residue Xaa = Ala, Asp, Asn; R = Boc, Z; R2, R3= H, Me, iPr). The aza‐analogue of an amino acid residue appears to be a strong p‐turn‐inducing motif, and the AzAsn carboxamide side‐chain is capable of interacting, as a proton donor, with the preceding peptide carbonyl group.