Differential carbohydrate recognition of two GlcNAc-6-sulfotransferases with possible roles in L-selectin ligand biosynthesis

Two human GlcNAc-6-sulfotransferases, CHST2 and HEC-GlcNAc6ST, have been re cently identified as possible contributors to the inflammatory response by virtue of their participation in L-selectin ligand biosynthesis. Selective inhibitors would facilitate their functional elucidation and might provide leads for antiinflammatory therapy. Here we investigate the critical elemen ts of a disaccharide substrate that are required for recognition by CHST2 a nd HEC-GlcNAc6ST. A panel of disaccharide analogues, bearing modifications to the pyranose rings and aglycon substituents, were synthesized and screen ed for substrate activity with each enzyme. Both GlcNAc-6-sulfotransferases required the 2-N-acetamido and 4-hydroxyl groups of a terminal GlcNAc resi due for conversion to product. Both enzymes tolerated modifications to the reducing terminal pyranose. Key differences in recognition of an amide grou p in the aglycon substituent were observed, providing the basis for future glycomimetic inhibitor design.