Abstract
Chondroitin sulfate (CS) is a sulfated polysaccharide that plays essential physiological roles. Here, we report an enzyme-based method for the synthesis of a library of 15 different CS oligosaccharides. This library covers 4-O-sulfated and 6-O-sulfated oligosaccharides ranging from trisaccharides to nonasaccharides. We also describe the synthesis of unnatural 6-O-sulfated CS pentasaccharides containing either a 6-O-sulfo-2-azidogalactosamine or a 6-O-sulfogalactosamine residue. The availability of structurally defined CS oligosaccharides offers a novel approach to investigate the biological functions of CS.