Antithrombin III-Binding Site Analysis of Low-Molecular-Weight Heparin Fractions

Low-molecular-weight heparins (LMWHs) are widely used as clinical anticoagulant drugs. LMWHs are heterogeneous and highly negatively charged glycans prepared by chemical or enzymatic depolymerization of unfractionated heparin. The detailed structural analysis of a LMWH is essential for the drug quality control. In this study, an LMWH, enoxaparin sodium (a generic version of Lovenox) was separated into different molecular weight fractions by a Superdex peptide column. The disaccharide compositions, 3-O-sulfo group-containing tetrasaccharides composition, and antithrombin III-binding affinity of the fractions from this LMWH were analyzed. The results showed that all the fractions had very similar disaccharide and 3-O-sulfo group-containing tetrasaccharide compositions, but the fraction containing larger-sized chains had higher antithrombin III-binding affinity.