The determination of complex carbohydrate structure by using carbonyl carbon resonances of peracetylated derivatives.

Carbonyl carbon resonances have been assigned to specific acetyl substituents in peracetylated derivatives of a variety of di- and tri-saccharides that occur as substructures of N- and O-linked glycoprotein glycans. Assignments were made by correlating shifts of these resonances to previously assigned pyranoid-ring proton and acetyl methyl proton shifts by means of 2D 13C-1H shifts correlation spectra. It was found that, when the shift assignment data for carbonyl carbon atoms, acetyl methyl protons, and pyranoid-ring protons are plotted in three dimensions, patterns appear that are unique to the different types of residues occurring in a parent structure. It is suggested that these shift data can complement existing 1H- and 13C-n.m.r. methods for determining primary structures of complex carbohydrates.