Enzymatic Synthesis of Homogeneous Chondroitin Sulfate Oligosaccharides

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.