title: Chemoenzymatic synthesis of a 3IV,6III-disulfated Lewis(x) pentasaccharide, a candidate ligand for human L-selectin.
abstract: The disulfated pentasaccharide 3-O-SO3(-)-beta-D-Galp-(1-->4)-[alpha-L-Fucp-(1-->3)]-6-O-SO3(-)- beta-D-GlcpNAc-(1-->3)-beta-D-Galp-(1-->4)-D-Glcp was prepared according to a chemoenzymatic approach, starting from 4-methoxybenzyl O-(4-O-acetyl-2,6-di-O-benzyl-beta- D-galactopyranosyl)-(1-->4)-O-2,3,6-tri-O-benzyl-beta-D-glucopyranoside, obtained in six steps from hepta-O-acetyl lactosyl bromide. Coupling of this lactose derivative with O-(3,4,6-tri-O-acetyl-2-deoxy-2-phthalimido-beta-D-glucopyranosyl) trichloracetimidate afforded, after dephthaloylation and re-N-acetylation, 4-methoxybenzyl O-(2-acetamido-2-deoxy-beta-D- glucopyranosyl)-(1-->3)-O-(2,6-di-O-benzyl-beta-D-galactopyranosyl)-(1-- >4)- O-2,3,6-tri-O-benzyl-beta-D-glucopyranoside. Regioselective sulfation at the primary position of the glucosamine residue was then successfully achieved and the benzyl groups were removed. Enzymatic galactosylation of 4-methoxybenzyl O-(2-acetamido-2-deoxy-6-O-sulfo-beta-D- glucopyranosyl)-(1-->3)-O-beta-D-galactopyranosyl-(1-->4)-O-beta-D- glucopyranoside sodium salt, and subsequent regioselective sulfation at position 3 of the outer galactose residue through the stannylene procedure, led then to 4-methoxybenzyl O-(3-sulfo-beta-D- galactopyranosyl)-(1-->4)-O-(2-acetamido-2-deoxy-6-sulfo-beta-D- glucopyranosyl)-(1-->3)-O-beta-D-galactopyranosyl)-(1-->4)-O-beta-D- glucopyranoside disodium salt, which was finally fucosylated using human milk alpha-(1-->3/4)-fucosyltransferase affording, after anomeric deprotection, the target pentasaccharide.
authors.affiliation: Institut de Chimie Moléculaire d'Orsay, U.R.A. C.N.R.S. 462, Université de Paris-Sud, France.
authors.forename: A
authors.initials: A
authors.lastname: Lubineau
authors.forename: C
authors.initials: C
authors.lastname: Augé
authors.forename: N
authors.initials: N
authors.lastname: Le Goff
authors.forename: C
authors.initials: C
authors.lastname: Le Narvor
mesh_terms: D002240:Carbohydrate Sequence; D005647:Fucosyltransferases / Q000378:metabolism; D006801:Humans; D019041:L-Selectin / Q000378:metabolism; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000138:chemical synthesis* / Q000737:chemistry*; D011485:Protein Binding; D000080506:Sialyl Lewis X Antigen; D013431:Sulfates / Q000138:chemical synthesis*
chemical_list: D008024:Ligands; D009844:Oligosaccharides; D000080506:Sialyl Lewis X Antigen; D013431:Sulfates; D019041:L-Selectin; D005647:Fucosyltransferases