Studying the stereostructures of biomolecules and their analogs by vibrational circular dichroism

Abstract

The functions of biomacromolecules are largely governed by their stereostructure (i.e., configuration and conformation). Therefore, detailed understanding of their structural properties should help in regulating the functions of artificial macromolecules. However, studying the stereostructure of a molecule in the solution state is typically difficult due to the lack of suitable analytical techniques. Vibrational circular dichroism (VCD) spectroscopy, which measures circular dichroism in the infrared region, exhibits high sensitivity toward molecular stereostructures. In this paper, we first discuss a method for the elucidation of the stereostructures of small to large molecules based on theoretical calculations of VCD. The rest of the paper is dedicated to the applications of a VCD exciton chirality method, a novel approach recently developed by the authors to interpret VCD data by observing a VCD couplet in the C=O stretching region, to various biomolecules such as peptides, carbohydrates, polyesters and lipids. Vibrational circular dichroism (VCD) is effective for analyzing the configuration and conformation of various bio(macro)molecules. In addition to a conventional VCD approach using theoretical calculations, this review explains how the use of an exciton-type VCD couplet can be employed to elucidate the structures of bio(macro)molecules, such as carbohydrates, glycerophospholipids, proteins and polyesters.