SULFATION OF SIALYL LACTOSAMINE OLIGOSACCHARIDES BY CHONDROITIN 6-SULFOTRANSFERASE

We have previously shown that chondroitin 6-sulfotransferase (C6ST) ca talyzes transfer of sulfate not only to position 6 of GalNAc residue o f chondroitin but also to position 6 of Gal residue of keratan sulfate . In this study, we examined the sulfation of sialyl lactosamine oligo saccharides by C6ST, C6ST catalyzed transfer of sulfate to NeuAc alpha 2-3Gal beta l-4GlcNAc (SLN), NeuAc alpha 2-3Gal beta 1-4GlcNAc beta 1 -3Gal beta 1-4GlcNAc (SL2L4), NeuAc alpha 2-3Gal beta 1-4(6-sulfo)GlcN Ac beta 1-3(6-sulfo)Gal beta 1-4(6-sulfo)GlcNAc (SL2L4), and their des ialylated derivatives, but not to NeuAc alpha 2-3Gal beta 1-4(Fuc alph a 1-3)GlcNAc (SLe(x)). The sulfated product formed from SLN was degrad ed with neuraminidase and reduced with NaBH4. The resulting sulfated d isaccharide alditol showed the same retention time in SAX-HPLC as that of [H-3]Gal(6SO(4))beta 1-4GlcNAc-ol. The sulfated product formed fro m SLN was also degraded by a reaction sequence of neuraminidase digest ion, hydrazinolysis, deamination, and NaBH, reduction. The final produ ct was coeluted with [H-3]Gal(6SO(4))beta 1-4anhydromannitol in SAX-HP LC. These observations show that C6ST could transfer sulfate to positi on 6 of Gal residue of SLN, Incorporation of sulfate into SL2L4 was mu ch higher than the incorporation into SL1L1, suggesting that sulfate m oiety attached to adjacent GlcNAc residue may stimulate the transfer o f sulfate to Gal residue. The recombinant C6ST also catalyzed sulfatio n of the sialyl lactosamine oligosaccharides, indicating that a single protein catalyzes sulfation of chondroitin, keratan sulfate, and sial yl lactosamine oligosaccharides. These results raised a possibility th at C6ST may be one of the candidates involved in the biosynthesis of s ulfated sialyl Lewis x ligand for L-selectin.