Role of terminal fucose residues in clearance of human glycosylated alpha-amylase.
Human glycosylated alpha-amylase contains a single biantennary N-linked oligosaccharide that terminates with the structure Fuc alpha 1,3(Gal beta 1,4)GlcNAc. To examine the role of terminal fucose in the clearance of alpha-amylase, we used lectin affinity chromatography to isolate an alpha-amylase fraction that contains two terminal fucoses (one in each branch of the oligosaccharide) and a fraction from which both terminal fucoses have been enzymatically removed. In the rat, the rate of clearance of the radioiodinated fraction with terminal fucoses is rapid (t1/2 = 12 min) and is slowed by mannosylated but not galactosylated bovine serum albumin. The rate of clearance of the radioiodinated alpha-amylase fraction with no terminal fucoses is also rapid (t1/2 = 9.5 min), but the clearance is now slowed by galactosylated bovine serum albumin. These findings indicate that the fucosylated and defucosylated alpha-amylase fractions are recognized by different carbohydrate-specific receptors. We conclude therefore that terminal fucose is the recognition marker that effects the physiological clearance of this glycoprotein.
Tollefsen
S E
SE
Edward Mallinckrodt Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri.
Rosenblum
J L
JL
D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D002846:Chromatography, Affinity; D005643:Fucose; D006801:Humans; D008969:Molecular Sequence Data; D012463:Saliva / Q000201:enzymology*; D000516:alpha-Amylases / Q000302:isolation & purification / Q000378:metabolism*; D005644:alpha-L-Fucosidase
D005643:Fucose; D000516:alpha-Amylases; C057084:glycosylated alpha-amylase; D005644:alpha-L-Fucosidase