Trisaccharide Sulfate and Its Sulfonamide as an Effective Substrate and Inhibitor of Human Endo-O-sulfatase-1

Human endo- O -sulfatases (Sulf-1 and Sulf-2) are extracellular heparan sulfate proteoglycan (HSPG)-specific 6- O -endosulfatases, which regulate a multitude of cell-signaling events through heparan sulfate (HS)–protein interactions and are associated with the onset of osteoarthritis. These endo- O -sulfatases are transported onto the cell surface to liberate the 6-sulfate groups from the internal d -glucosamine residues in the highly sulfated subdomains of HSPGs. In this study, a variety of HS oligosaccharides with different chain lengths and N - and O -sulfation patterns via chemical synthesis were systematically studied about the substrate specificity of human Sulf-1 employing the fluorogenic substrate 4-methylumbelliferyl sulfate (4-MUS) in a competition assay. The trisaccharide sulfate IdoA2S-GlcNS6S-IdoA2S was found to be the minimal-size substrate for Sulf-1, and substitution of the sulfate group at the 6- O position of the d -glucosamine unit with the sulfonamide motif effectively inhibited the Sulf-1 activity with IC 50 = 0.53 μM, K i = 0.36 μM, and K D = 12 nM.