beta-1,4-Galactosyltransferase-catalyzed synthesis of the branched tetrasaccharide repeating unit of Streptococcus pneumoniae type 14.
A chemoenzymatic approach is described towards the branched tetrasaccharide repeating unit, beta-D-Galp- (1-->4)-beta-D-Glcp-(1-->6)-[beta-D-Galp-(1-->4)]-beta-D-GlcpNac, of Streptococcus pneumoniae type 14 in a form suitable for conjugation. The linear trisaccharide acceptor, beta-D-Galp-(1-->4)-beta-D-Glcp-(1-->6)-beta-D-GlcpNAc-(1-->O)CH2CH++ + = CH2, was synthesized by coupling of peracetylated lactosyl trichloroacetimidate to a suitably protected glucosamine building block and subsequent deprotection steps. The obtained derivative was found to be a good acceptor for bovine milk beta-1,4-galactosyltransferase, and the resulting branched tetrasaccharide beta-allyl glycoside was isolated and characterized by NMR spectroscopy and FAB mass spectrometry. Reaction of the anomeric allyl function with cysteamine under UV-irradiation gave the beta-aminoethylthio-extended glycoside suitable for further coupling of the tetrasaccharide to protein carriers.
Niggemann
J
J
Bijvoet Center, Department of Bio-Organic Chemistry, Utrecht University, The Netherlands. j.niggemann@chem.ruu.nl
Kamerling
J P
JP
Vliegenthart
J F
JF
D000818:Animals; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D002384:Catalysis; D002417:Cattle; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D009237:N-Acetyllactosamine Synthase / Q000378:metabolism*; D009844:Oligosaccharides / Q000096:biosynthesis*; D013296:Streptococcus pneumoniae / Q000378:metabolism*
D009844:Oligosaccharides; D009237:N-Acetyllactosamine Synthase