Synthesis and conformation in the solid state of oligopeptides with the L-alanyl-L-leucylglycyl sequence in which some glycines are replaced with N-methylglycines

Abstract

A number of oligopeptides consisting of L-alanyl-L-leucylglycyl sequences in which some glycyl residues are replaced with N-methylglycyl residues were prepared by the fragment condensation method using Nps-L-Ala-L-Leu-Gly-ONSu and Nps-L-Ala-L-Leu-Sar-ONSu. Conformations in the solid state of the peptides were examined by i.r. spectroscopy. The shortest peptide length for the formation of an α-helix is three successive L-alanyl-L-leucylglycyl residues situated between L-alanyl-L-leucylsarcosyl residues.