Comparative structural study of the N-linked oligosaccharides of human normal and pathological immunoglobulin G

Abstract

The structures of oligosaccharides of normal and pathological immunoglobulin G (IgG) are reported. Asparagine-linked neutral oligosaccharides were released by N-oligosaccharide glycopeptidase (almond) digestion. The reducing ends of the oligosaccharide chains thus obtained were aminated with a fluorescent reagent, 2-aminopyridine, and the mixture of pyridylamino derivatives of the oligosaccharides was separated by reverse-phase high-performance liquid chromatography. It was possible to separate 15 out of the 16 kinds of oligosaccharides that have been suggested to exist in normal human IgG. High-resolution proton nuclear magnetic resonance spectroscopy was used along with chemical methods to determine the structures of the separated oligosaccharides. It has been shown that in normal IgG a biantennary complex-type oligosaccharide with a fucose residue (formula; see text) is predominant and four kinds of oligosaccharides, which are biantennary with bisecting N-acetylglucosamine and without fucose residues, exist only in a very small quantity. The results obtained for normal IgG were compared with those obtained for three myeloma IgG proteins. It has been found that the most abundant species that exist in the pathological proteins analyzed in the present work lack one or two galactose residues at the nonreducing terminal. We show that the fractions of fucose-containing oligosaccharides are markedly decreased in the heavy-chain disease protein Per. It is of particular interest that in this paraprotein the major component is a biantennary complex-type oligosaccharide that lacks a fucose residue and an oligosaccharide with the structure (Formula: see text) exists as one of the most abundant components.

Structural analysis of the N‐linked carbohydrate chains of the 55‐kDa glycoprotein family (PZP3) from porcine zona pellucida

“…Sequential digestion of N2 oligosaccharide released two galactose residues with @-galactosidase, two GlcNAc residues with @-N-acetylglucosaminidase, two mannose residues with a-mannosidase, and one mannose residue with @-mannosidase (Table 3). The values of chemical shifts of N2 agreed with those of the pyridylamino derivatives of oligosaccharide H from human IgG [23] and oligosaccharide E from urinary erythropoietin [24] (Table 4). Accordingly, the structure of N2 was proposed as that of (3) in Fig.…”

“…Jvalues are shown in the angled brackets. IgG-E results are from [23] The idcntity of the peaks eluted within 20 min from octadccylsilane (Fig. 8C) is unclear.…”

Peptide‐N4‐(N‐acetyl‐β‐glucosaminyl)asparagine amidase F cannot release glycans with fucose attached α1 → 3 to the asparagine‐linked N‐acetylglucosamine residue

“…Notably under these conditions, which also have been used for defucosylation of bromelain and peroxidase, most of the fucose, which is a1 6 linked to Asn-GlcNAc in IgG [31], was retained ( Table 3). The tryptic human IgG glycopeptide was isolated the same way as BrlPep except that DEAE-Sephadex A25 was used.…”

“…A tryptic glycopeptide from human IgG, containing fucose a1 -+6 linked to Asn-GlcNAc [31], was chosen to compare the enzymatic activities of PNGase A and PNGase F with a substrate of mammalian origin. For both enzymes, human IgG glycopeptide was the best substrate among those employed (Fig.…”

My 30 Years in the Dream of the structural Analyses of the N-linked Oligosaccharides: The Discovery of Glycoamidase A to the Development of the GALAXY Database

“…Another study (20) was theˆrst to show the diŠer-ences between normal and pathological human IgG oligosaccharides by using HPLC.…”