Differentiation of 3-O-Sulfated Heparin Disaccharide Isomers: Identification of Structural Aspects of the Heparin CCL2 Binding Motif

The presence of 3-O-sulfated glucosamine residues in heparin or heparan sulfate plays a role in binding to antithrombin III and HSV infection. In this study, tandem mass spectrometry was used to differentiate between two heparin disaccharide isomers containing variable sulfate at C6 in a common disaccharide and C3 in a more rare one. The dissociation patterns shown by MS 2 and MS 3 were clearly distinguishable between the isomers, allowing their differentiation and quantitation. Using this technique, we show that an octasaccharide with 11 sulfate groups with high affinity for inflammatory chemokine CCL2 does not contain 3-O-sulfated disaccharides. CID was used to distinguish between heparin disaccharide isomers containing or lacking 3-O-sulfation and applied to evaluate the involvement of 3-O-sulfation in the heparin/CCL2 interaction.