Peptoid Residues and beta-Turn Formation

We synthesized and tested for intramolecularly H-bonded beta-turn formation a set of terminally protected tripeptoids containing in position i+1/i+2 either a residue of N-methylglycine or of N-isobutylglycine. By exploiting FT-IR absorption and 1H NMR techniques we compared their folding tendencies with those of a variety of reference peptides. The amount of beta-turn induction and the relative extent of the various types of intramolecularly H-bonded beta-turn conformers were determined in chloroform solution.