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 ($\chembond{1,0} $NH$\chembond{1,0} $CO$\chembond{1,0} $) group have been critically reviewed in the light of new data on N-monosubstituted amides. Evidence based on hydrogen bonding studies, substitution of deuterium for hydrogen on the peptide NH, and dichroism in oriented proteins has confirmed the previous association of several high-frequency bands with peptide group oscillations. A new assignment for a peptide band near 4600 cm$^{-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.