The near infra-red spectrum of the peptide group

Abstract

The assignments of high-frequency absorption bands in the spectra of compounds con­taining the peptide (—NH—CO—) group have been critically reviewed in the light of new data on N -monosubstituted amides. Evidence based on hydrogen bonding studies, sub­stitution of deuterium for hydrogen on the peptide NH, and dichroism in oriented proteins has confirmed the previous association of several high-frequency bands with peptide group oscillations. A new assignment for a peptide band near 4600 cm -1 is suggested in order to explain its dichroism. The analytical use of a band at 5130 cm -1 due to H 2 O associated with compounds containing the peptide group has been established.