Abstract
We report the preparation of size-defined [(15)N]N-acetylheparosan oligosaccharides from Escherichia coli-derived (15)N-enriched N-acetylheparosan. Optimized growth conditions of E. coli in minimal media containing (15)NH(4)Cl yielded [(15)N]N-acetylheparosan on a preparative scale. Depolymerization of [(15)N]N-acetylheparosan by heparitinase I yielded resolvable, even-numbered oligosaccharides ranging from disaccharide to icosaccharide. Anion-exchange chromatography-assisted fractionation afforded size-defined [(15)N]N-acetylheparosan oligosaccharides identifiable by ESI-TOFMS. These isotopically labeled oligosaccharides will prove to be valuable research tools for the chemoenzymatic synthesis of heparin and heparan sulfate oligosaccharides and for the study of their structural biology.