Lu G, Holland LA. Profiling the N-Glycan Composition of IgG with Lectins and Capillary Nanogel Electrophoresis.
Anal Chem 2018;
91:1375-1383. [PMID:
30525457 PMCID:
PMC6335613 DOI:
10.1021/acs.analchem.8b03725]
[Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
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Glycosylated human
IgG contains fucosylated biantennary N-glycans with
different modifications including N-acetylglucosamine,
which bisects the mannose core. Although
only a limited number of IgG N-glycan structures
are possible, human IgG N-glycans are predominantly
biantennary and fucosylated and contain varying levels of α2–6-linked
sialic acid, galactose, and bisected N-acetylglucosamine.
Monitoring the relative abundance of bisecting N-acetylglucosamine
is relevant to physiological processes. A rapid, inexpensive, and
automated method is used to successfully profile N-linked IgG glycans
and is suitable to distinguish differences in bisection, galactosylation,
and sialylation in N-glycans derived from different
sources of human IgG. The separation is facilitated with self-assembled
nanogels that also contain a single stationary zone of lectin. When
the lectin specificity matches the N-glycan, the
peak disappears from the electropherogram, identifying the N-glycan structure. The nanogel electrophoresis generates
separation efficiencies of 500 000 plates and resolves the
positional isomers of monogalactosylated biantennary N-glycan and the monogalactosylated bisected N-glycan. Aleuria aurantia lectin, Erythrina cristagalli lectin (ECL), Sambucus nigra lectin, and Phaseolus vulgaris Erythroagglutinin (PHA-E) are used to
identify fucose, galactose, α2–6-linked sialic acid,
and bisected N-acetylglucosamine, respectively. Although
PHA-E lectin has a strong binding affinity for bisected N-glycans that also contain a terminal galactose on the α1–6-linked
mannose branch, this lectin has lower affinity for N-glycans containing terminal galactose and for agalactosylated bisected
biantennary N-glycans. The lower affinity to these
motifs is observed in the electropherograms as a change in peak width,
which when used in conjunction with the results from the ECL lectin
authenticates the composition of the agalactosylated bisected biantennary N-glycan. For runs performed at 17 °C, the precision
in migration time and peak area was less than or equal to 0.08 and
4% relative standard deviation, respectively. The method is compatible
with electrokinetic and hydrodynamic injections, with detection limits
of 70 and 300 pM, respectively.
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