Spectrum-structure relationship in carbohydrate vibrational circular dichroism and its application to glycoconjugates

Preliminary reports of the nature of the vibrational circular dichroism (VCD) peak at around 1145 cm(-1), which is characteristic of axial glycosidic sugars and is called the glycoside band (J. Am. Chem. Soc. 2004, 126, 9496), have been thoroughly examined. Through systematic carbohydrate measurements, it was found that the sign of the glycoside band reflects not only the anomeric configuration but also the pyranose conformation. Isotope and theoretical studies characterized its vibrational mode as C1-H1 deformation coupled with C1-O1 stretching, which indicates its applicability to more-complicated glycoconjugates. In this study, for the first time, carbohydrate VCD spectra were reliably predicted by means of density functional theory (DFT) calculations. The VCD technique was applied to glycopeptides, and simultaneous analysis of both the carbohydrate and aglycan parts was carried out.