Chemoenzymatic Synthesis of Homogeneous Heparan Sulfate and Chondroitin Sulfate Chimeras

Heparan sulfate (HS) and chondroitin sulfate (CS) are two structurally distinct natural polysaccharides. Here, wereport the synthesis of a library of seven structurally homogeneous HS and CS chimeric dodecasaccharides (12-mers). The synthesiswas accomplished using six HS biosynthetic enzymes and four CS biosynthetic enzymes. The chimeras contain a CS domain on thereducing end and a HS domain on the nonreducing end. The synthesized chimeras display anticoagulant activity as measured byboth in vitro and ex vivo experiments. Furthermore, the anticoagulant activity ofH/C 12-mer 5is reversible by protamine, a U.S.Food and Drug Administration-approved polypeptide to neutralize anticoagulant drug heparin. Ourfindings demonstrate thesynthesis of unnatural HS-CS chimeric oligosaccharides using natural biosynthetic enzymes, offering a new class of glycan moleculesfor biological research.