Preparation and characterization of heparin hexasaccharide library with N-unsubstituted glucosamine residues.

The rare N-unsubstituted glucosamine (GlcNH3(+)) residues in heparan sulfate (HS) have important biological and pathophysiological roles. Therefore, the ability to chemically generate a series of oligosaccharides, which have a similar structure to the naturally-occurring, GlcNH3(+)--containing oligosaccharides from HS, would greatly contribute to investigating their natural role in HS. In this study, a hexasaccharide library that possess GlcNH3(+) residues were prepared from the chemical modification of the fully sulfated dp6. Chemical reaction conditions were optimized to generate different pattern of GlcNH3(+)--containing oligosaccharides, then the structure of the library was detected by high-performance liquid chromatography-ion trap/time-of-flight mass spectrometry (LC/MS-ITTOF) analysis. EIC/MS and MS(2) analysis showed different fragmentation patterns of dp6s with different GlcNH3(+) residues. This provides a foundation for further identification and quantification of GlcNH3(+)--oligosaccharides by mass spectrum analysis.