Oligosaccharide specificity of normal human hepatocyte alpha 1-3 fucosyltransferase.
A purified alpha 1-3 fucosyltransferase (alpha 1-3 FT) was recovered in the Golgi fraction of isolated hepatocytes from normal human liver tissue. The efficiency of purification was controlled by measurement of fucose transfer to asialotransferrin (for alpha 1-3 FT), to phenyl-beta-D-galactose (for alpha 1-2 FT) and to 2' fucosyl lactose (for alpha 1-3/4 FT). The initial hepatocyte isolation step got rid of 97% and 94% of alpha 1-2 and alpha 1-3/4 total liver FT, respectively. After Golgi enrichment (26-fold purification and a yield of 7.6%), alpha 1-3 FT extract expressed a specific activity of 2 pM/min per mg protein. When incubated in optimized conditions with type 1, 2 or 6 oligosaccharide acceptors (10 mM), hepatocellular alpha 1-3 FT efficiently transferred fucose to N-acetyllactosamine and its 3' sialylated derivative, but poorly to lactose. When incubated with neutral or sialylated biantennary N-glycans, the enzyme expressed the highest affinity (Km = 0.38 mM) for the 3'bisialylated derivative. This suggests that hepatocellular alpha 1-3 FT is involved in the synthesis of sialosyl Le(x) determinants on cirrhotic alpha 1AGP.
Jezequel-Cuer
M
M
Laboratoire de Biochimie A, Hôpital Bichat, Paris, France.
N'Guyen-Cong
H
H
Biou
D
D
Durand
G
G
D002240:Carbohydrate Sequence; D002458:Cell Fractionation; D005647:Fucosyltransferases / Q000302:isolation & purification / Q000378:metabolism*; D006031:Glycosylation; D006056:Golgi Apparatus / Q000201:enzymology; D006801:Humans; D007700:Kinetics; D008099:Liver / Q000201:enzymology* / Q000648:ultrastructure; D008969:Molecular Sequence Data; D009439:Neuraminidase / Q000378:metabolism; D009844:Oligosaccharides / Q000378:metabolism*; D013379:Substrate Specificity
D009844:Oligosaccharides; D005647:Fucosyltransferases; C031692:galactoside 3-fucosyltransferase; D009439:Neuraminidase