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Determination of O-fucosylation Sites in IgG from Sera of Juvenile Chronic Arthritis Patients with Electrospray Quadrupole Time-of-Flight Mass Spectrometry (ESI Q-TOF MS)

Immunoglobulin G (IgG) is a 150 kD glycoprotein and the most abundant type among human antibodies. The molecule exhibits very complex tertiary structure with variable domains, hypervariable regions and conserved N-glycosylation whose changes are shown to be connected with several autoimmune diseases. Recent analysis of the IgG glycosylation in Juvenile Chronic Arthritis (JCA, an autoimmune rheumatic disease) and related autoimmune diseases indicated a high increase of O-linked fucosylation which is potentially significant in early diagnostics of these diseases (patent pending). Determination of the targeted fucosylation sites could have profound importance in elucidation of their molecular pathogeneses, but the variability of the molecule, hence the heterogeneity of IgG samples purified directly from human sera, hampers any straightforward analysis with standard biochemical and MS methods. The aim of this work was to challenge a method for rapid structural analysis of fucosylated peptides with ESI Q-TOF MS. Using this recently developed strategy, mapping of the possible fucosylation sites on IgG molecules isolated directly from sera of JCA patients was performed. Large portions of the IgG constant regions were found to be excluded as targets for O-fucosylation and at least one O-fucosylation site on the Igg1 chain was determined.

O-fucosylation; Juvenile Chronic Arthritis; IgG

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