1H and 13C n.m.r. studies of pseudo‐peptide analogues of the C‐terminal tetrapeptide of gastrin

1H and 13C n.m.r. study of pseudo-peptide analogues of the C-terminal tetrapeptide of gastrin, obtained by replacing each peptide bond by a “reduced peptide bond”, one at a time, e.g. Boc-Trpo(CH2NH)Leu-Asp-Phe-NH22, Boc-Trp-Leuo(CH2NH)Asp-Phe-NH23, Boc-Trp-Leu-Aspo(CH2NH)Phe-NH24, were reported. The CH2NH bond was completely characterized. 1H and 13C spectroscopic data were reported. It appeared from the present work that the modifications produced by the replacement of a peptide bond by a CH2NH bond were localized around the CH2NH.