Enzymatic characterization of UDP-galactose:FdSdG galactosyltransferase in purified liver plasma membrane.
This study yields evidence for the localization of a galactosyltransferase in purified liver plasma membranes, with the following results. The purified plasma membranes contained galactosyltransferases which transfered galactose from UDP-galactose into desialylated-degalactosylated fetuine. A suitable system of glycosylation reaction was defined. It contained: 10 mM Tris-HCl pH 7.4, 5 mM Mn2+, 4 mM NaF. For the assay with exogenous acceptors, 1.6 mg/ml of desialylated-degalactosylated fetuine and 0.1% of triton X-100 were added. The apparent Km values for UDP-galactose were about 10(-5) M. Enzymatic activities required Mn2+. This cation appeared to be a linear non-competitive activator when used at concentrations below 5 mM. Mg2+ and Ca2+ had an inhibitory effect on Mn2+-dependant-galactosyltransferase.
Fernandez-Briera
A
A
Department of Biochemistry and Molecular Biology, University of Lyon, Spain.
Louisot
P
P
Morelis
R
R
D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002458:Cell Fractionation; D002462:Cell Membrane / Q000201:enzymology; D004789:Enzyme Activation / Q000187:drug effects; D005700:Galactosyltransferases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D008274:Magnesium / Q000494:pharmacology; D008345:Manganese / Q000494:pharmacology; D051379:Mice; D014531:Uridine Diphosphate Galactose / Q000378:metabolism
D014531:Uridine Diphosphate Galactose; D008345:Manganese; D005700:Galactosyltransferases; D008274:Magnesium; D002118:Calcium