Chemical-Enzymatic Synthesis of A Branched Hexasaccharide Fragment of Type Ia Group B Streptococcus Capsular Polysaccharide
Titel:
Chemical-Enzymatic Synthesis of A Branched Hexasaccharide Fragment of Type Ia Group B Streptococcus Capsular Polysaccharide
Auteur:
Zou, Wei Jennings, Harold J.
Verschenen in:
Journal of carbohydrate chemistry
Paginering:
Jaargang 15 (1996) nr. 8 pagina's 925-937
Jaar:
1996-11-01
Inhoud:
A branched hexasaccharide fragment of type Ia group B streptococcal polysaccharide, α-NeuAc(2→3)-β-D-Gal(1→4)-β-D-GlcNAc(1→3)-[β-D-Glc(1→4)]-β-D-Gal(1→4)-β-D-Glc-OMe (13), has been synthesized by chemical-enzymatic procedures. Chemical synthesis of a pentasaccharide, β-D-Gal(1→4)-β-D-GlcNAc(1→3)-[β-D-Glc(1→4)]-β-D-Gal(1→4)-β-D-Glc-OMe (12), was achieved from glycosyl donor, 4-O-(2,3,4,6-tetra-O-acetyl-β-D-galactopyranosyl)-3,6-di-O-acetyl-2-deoxy-2-phthalimido-β-D-glucopyranosyl trichloroacetimidate (9), and acceptor, methyl O-(2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyl)-(1→4)-O-(2,6-di-O-benzyl-β-D-galactopyranosyl)-(1→4)-2,3,6-tri-O-benzyl-β-D-glucopyranoside (6), by block condensation in 41% yield. Following enzymatic sialylation of 12 at the 3-O-position of its terminal galactopyranosyl residue using recombinant α-(2→3)-sialyltransferase and CMP-NeuAc afforded 13 in 59% yield.
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