C-2 Epimerization of N-Acetylglucosamine in an Oligosaccharide Derived From Heparan Sulfate

The isolation of a heparan sulfate derived tetrasaccharide containing N-acetylmannosamine is described. The N-acetylmannosamine residue at the reducing terminus of heparin lyase derived tetrasaccharide is formed by base catalyzed C-2 epimerization of N-acetylglucosamine. This C-2 epimerization takes place under very mild conditions suggesting that this residue may be formed in small amounts under physiologic conditions.