9 - INFRA-RED SPECTRA

Abstract

This chapter discusses infra-red spectra. Although the potentialities of infra-red spectroscopy in the field of protein analysis have long been appreciated it is only comparatively recently that our understanding of the nature of protein spectra has advanced sufficiently for the method to be of interest to the protein chemist. In contrast to most other methods of protein analysis the present limitations of infra-red spectroscopy are set almost entirely by problems of interpretation rather than by experimental difficulties. In contrast to X-ray diffraction studies, which are primarily concerned with crystalline material, the infra-red spectrum gives information about both crystalline and non-crystalline components in fibrous structures. In this regard the two techniques are complementary and they have proved a powerful combination in structural studies of the fibrous proteins and synthetic polypeptides. At the present time studies of the frequency shifts associated with configurational changes and the reaction of proteins with deuterium oxide appear to be the most rewarding fields of study.