Selective defucosylation by mercaptolysis. A potential step in analyzing branched oligosaccharides.
A method of stepwise chemical degradation was elaborated on a microgram quantity of 3-O-alpha-L-fucosyllactose. The key step, TiCl4-catalysed dithioacetal formation from the permethylated N-4-nitrophenyl triosylamine (4) was accompanied by quantitative defucosylation. [14C]Acetylation of the dried mercaptalation mixture gave radiolabelled 3,5-di-O-[14C]acetyl-4-O-(2,3,4,6-tetra-O-methyl-beta-D-galactopyranosyl )-2 , 6-di-O-methyl-D-glucose diethyl dithioacetal (7) and 5-O-[14C]acetyl-2,3,4-tri-O-methyl-L-fucose diethyl dithioacetal (8). The former was further degraded via the bis(sulfone), and thereby 2,3,4,6-tetra-O-methyl-D-galactose (13) was expelled. The monosaccharide branches, fucose and galactose, were identified as derivatives 8 and 13, respectively, by comparison with authentic samples. Isolation of microquantities of products was carried out by preparative TLC.
Lehmann
J
J
Institut für Organische Chemie und Biochemie der Universität Freiburg, Germany.
Petry
S
S
Scheuring
M
M
Schmidt-Schuchardt
M
M
D000107:Acetylation; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D002250:Carbon Radioisotopes; D006868:Hydrolysis; D007202:Indicators and Reagents; D009682:Magnetic Resonance Spectroscopy; D008832:Microchemistry / Q000379:methods; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000737:chemistry*; D014025:Titanium
D002250:Carbon Radioisotopes; D007202:Indicators and Reagents; D009844:Oligosaccharides; C035714:3'-fucosyllactose; C025096:titanium tetrachloride; D014025:Titanium