title: Sialylation of n-alkyllactosides, galactosides and glucosides by sialyltransferases from rat liver Golgi vesicles.
abstract: n-Alkyl alpha- and beta-lactosides, galactosides and glucosides with different alkyl chain lengths (C2, C8, C14 and C20) were synthesized and used as acceptors for sialyltransferases from rat liver Golgi vesicles. The beta-galactosides, beta-glucosides, and both alpha- and beta-lactosides, were sialylated. Keeping the acceptor concentration constant, sialylation rates reached a maximum for the n-octyl alpha- and beta-lactosides, n-octyl beta-galactoside and n-octyl beta-glucoside, respectively. n-Octyl alpha-galactoside and n-octyl alpha-glucoside were not sialylated. The reaction products were characterized by TLC. With n-octyl lactoside and galactoside as acceptors, two major sialylation products were formed. They could be separated by preparative TLC, and their structures were identified as 2-3 and 2-6 sialylated acceptors, respectively, by a combination of periodate oxidation, NaBD4 reduction, permethylation and subsequent analysis by fast atom bombardment mass spectrometry (FAB-MS). The structure of the single product obtained from n-octyl beta-glucoside was determined to be the 2-6 sialylated glucoside. Competition experiments with n-octyl lactoside and lactosylceramide and ganglioside Gal beta 1-3GalNAc beta 1-4(NeuAc alpha 2-3)Gal beta 1-4Glc beta 1-1Cer (GM1) as acceptors for sialyltransferases suggested that SAT-I [NeuAc alpha 2-3Gal beta 1-4Glc beta 1-1Cer (GM3) synthase] was at least in part responsible for the 2-3 sialylation of n-octyl lactoside.
authors.affiliation: Institut für Physiologische Chemie, Universität Bonn, FRG.
authors.forename: G
authors.initials: G
authors.lastname: Pohlentz
authors.forename: M
authors.initials: M
authors.lastname: Trimborn
authors.forename: H
authors.initials: H
authors.lastname: Egge
mesh_terms: D000818:Animals; D001667:Binding, Competitive; D002240:Carbohydrate Sequence; D002855:Chromatography, Thin Layer; D005697:Galactosides / Q000378:metabolism*; D005960:Glucosides / Q000378:metabolism*; D006027:Glycosides / Q000378:metabolism*; D006056:Golgi Apparatus / Q000201:enzymology*; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D008969:Molecular Sequence Data; D051381:Rats; D012799:Sialyltransferases / Q000378:metabolism*; D016339:Spectrometry, Mass, Fast Atom Bombardment
chemical_list: D005697:Galactosides; D005960:Glucosides; D006027:Glycosides; C008245:lactosides; D012799:Sialyltransferases