Substrate specificity of cerebral GDP-fucose: glycoprotein fucosyltransferase.
Solubilized sheep brain fucosyltransferase was shown to transfer fucose from GDP-fucose onto glycoprotein and glycopeptide acceptors, such as asialofetuin, asialotransferrin, their glycopeptides and glycopeptides from ovalbumin, but not on to monosaccharides and disaccharides such as galactose, N-acetylglucosamine and lactose. Competition studies between asialofetuin and glycopeptide V from ovalbumin provided evidence that both substrates compete for a common enzyme active site. The position of the fucosyl linkage was then investigated. Endo-beta-N-glucosaminidase D digestion of fucosylated and acetylated glycopeptide V showed that fucose is not linked to asparagine-linked N-acetylglucosamine. Hydrazinolysis and nitrous acid deamination performed on asialofetuin and glycopeptide V proved that fucose is not linked to external galactose or N-acetylglucosamine either. Thus we assume that fucose is linked to the oligomannochitobiosyl core of the glycan, and probably to the second N-acetylglucosamine.
D000118:Acetylglucosaminidase / Q000378:metabolism; D000818:Animals; D001212:Asialoglycoproteins; D001665:Binding Sites; D001921:Brain / Q000201:enzymology*; D002845:Chromatography / Q000379:methods; D060748:Fetuins; D005643:Fucose / Q000378:metabolism; D005647:Fucosyltransferases / Q000378:metabolism*; D006020:Glycopeptides / Q000378:metabolism; D006023:Glycoproteins / Q000378:metabolism; D006602:Hexosyltransferases / Q000378:metabolism*; D066298:In Vitro Techniques; D017038:Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase; D012756:Sheep; D013379:Substrate Specificity; D000509:alpha-Fetoproteins / Q000378:metabolism; D005644:alpha-L-Fucosidase / Q000378:metabolism
D001212:Asialoglycoproteins; D060748:Fetuins; D006020:Glycopeptides; D006023:Glycoproteins; D000509:alpha-Fetoproteins; C017029:asialofetuin; D005643:Fucose; D005647:Fucosyltransferases; D006602:Hexosyltransferases; C020559:Glycoprotein 6-alpha-L-fucosyltransferase; D005644:alpha-L-Fucosidase; D000118:Acetylglucosaminidase; D017038:Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase