Synthesis of sulfated phenyl 2-acetamido-2-deoxy-D-galactopyranosides. 4-O-Sulfated phenyl 2-acetamido-2-deoxy-β-D-galactopyranoside is a competitive acceptor that decreases sulfation of chondroitin sulfate by N-acetylgalactosamine 4-sulfate 6-O-sulfotran

We have previously cloned N-acetylgalactosamine 4-sulfate 6-O-sulfotransferase (GalNAc4S-6ST), which transfers sulfate from 3′-phosphoadenosine 5′-phosphosulfate (PAPS) to the C-6 hydroxyl group of the GalNAc 4-sulfate residue of chondroitin sulfate A and forms chondroitin sulfate E containing GlcA-GalNAc(4,6-SO4) repeating units. To investigate the function of chondroitin sulfate E, the development of specific inhibitors of GalNAc4S-6ST is important. Because GalNAc4S-6ST requires a sulfate group attached to the C-4 hydroxyl group of the GalNAc residue as the acceptor, the sulfated GalNAc residue is expected to interact with GalNAc4S-6ST and affect its activity. In this study, we synthesized phenyl α- or -β-2-acetamido-2-deoxy-β-D-galactopyranosides containing a sulfate group at the C-3, C-4, or C-6 hydroxyl groups and examined their inhibitory activity against recombinant GalNAc4S-6ST. We found that phenyl β-GalNAc(4SO4) inhibits GalNAc4S-6ST competitively and also serves as an acceptor. The sulfated product derived from phenyl β-GalNAc(4SO4) was identical to phenyl β-GalNAc(4,6-SO4). These observations indicate that derivatives of β-D-GalNAc(4SO4) are possible specific inhibitors of GalNAc4S-6ST.