n-alkylglucosides serve as acceptors for galactosyltransferases from rat liver Golgi vesicles.
n-Alkyl alpha- and beta-D-glucopyranosides with different alkyl chain lengths (Glc-O-CxH2x+1) and n-octyl beta-D-thioglucopyranoside (Glc-S-C8H17) were synthesized, and used as acceptors for galactosyltransferases from rat liver Golgi vesicles. Only the beta-anomers were galactosylated and at constant substrate concentration, the reaction rates reached a maximum for medium alkyl chain lengths (C6, C8 and C10). Apparent Km and Vmax values decreased with increasing alkyl chain length. The reaction products were identified as n-alkyl beta-lactosides by means of thin layer chromatography, fast atom bombardment mass spectrometry and 1H-NMR spectroscopy. Competition experiments showed that UDP-Gal: N-acetylglucosamine beta 1-4-galactosyltransferase (EC 2.4.1.38) and not UDP-Gal: glucosylceramide beta 1-4-galactosyltransferase (lactosylceramide synthase, GalT-2) was responsible for the galactosylation of alkyl glucosides.
Pohlentz
G
G
Institut für Physiologische Chemie, Universität Bonn, Germany.
Trimborn
M
M
Egge
H
H
D000818:Animals; D001667:Binding, Competitive / Q000187:drug effects; D002855:Chromatography, Thin Layer; D005700:Galactosyltransferases / Q000378:metabolism*; D006027:Glycosides / Q000138:chemical synthesis / Q000378:metabolism*; D006056:Golgi Apparatus / Q000201:enzymology / Q000378:metabolism*; D007700:Kinetics; D008099:Liver / Q000201:enzymology / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D051381:Rats; D016339:Spectrometry, Mass, Fast Atom Bombardment; D013329:Structure-Activity Relationship
D006027:Glycosides; D005700:Galactosyltransferases