A. Tanaka et al., Evidence for a site-specific fucosylation of N-linked oligosaccharide of immunoglobulin A1 from normal human serum, GLYCOCON J, 15(10), 1999, pp. 995-1000
Glycopeptides containing the N-linked oligosaccharide from human serum IgA1
were analyzed by matrix-assisted laser desorption ionization time-of-fligh
t mass spectrometry (MALDI-TOFMS). Two glycopeptides, GP1 and GP2, prepared
from the endoproteinase Asp-N digest of the IgA1 heavy chain, were derived
from the CH2 domain (N-glycan site at Asn(263)) and the tailpiece portion
(N-glycan site at Asn(459)), respectively. The structure of the attached su
gar chain was deduced from the mass number of the glycopeptide and confirme
d by a two-dimensional mapping technique for a pyridylaminated oligosacchar
ide. GP1 was composed of two major components having a fully galactosylated
bianntena sugar chain with or without a bisecting N-acetylglucosamine (Glc
NAc) residue. On the other hand, the GP2 fraction corresponded to the glyco
peptides having a fully galactosylated and fucosylated bianntena sugar chai
n partly bearing a bisecting GlcNAc residue. Thus, the site-specific fucosy
lation of the N-linked oligosaccharide on the tailpiece of the al chain bec
ame evident for normal human serum IgA1.