title: Sialic acid methylation refines capillary electrophoresis laser-induced fluorescence analyses of immunoglobulin G N-glycans of ovarian cancer patients.
abstract: Alterations in IgG N-glycosylation coincide with the development of a number of diseases including cancer and could potentially be used as diagnostic markers. CE-LIF of 8-aminopyrene-1,3,6-trisulfonic acid labeled N-glycans is a well-established rapid method to characterize IgG N-glycans that needs only low amounts of starting material. However,sialylated N-glycans have short migration times due to their negative charge. As a result,some of them are not well resolved and co-migrate with neutral glycans. In this work, we neutralized the negative charge of sialic acids by methylation and optimized the protocol using the commercially available disialylated biantennary oligosaccharide (A2G2S2). IgGN-glycans isolated from healthy human serum were then analyzed using this method. We could demonstrate that co-migration of A2, FA2G2S1, and FA2B[3]G1S1 was prevented,which allowed an accurate quantification of these N-glycans. Finally, we investigated the IgG N-glycan profiles of patients suffering from ovarian cancer using the conventional and methylation methods.With both methods, we observed an increase of agalactosylated structures that was accompanied by a decrease in digalactosylated structures. Finally, using the methylation protocol, we could further demonstrate an increase of A2, which was technically impossible with the conventional method.
authors.forename: Christian
authors.initials: C
authors.lastname: Schwedler
authors.forename: Matthias
authors.initials: M
authors.lastname: Kaup
authors.forename: Dominique
authors.initials: D
authors.lastname: Petzold
authors.forename: Berthold
authors.initials: B
authors.lastname: Hoppe
authors.forename: Elena Iona
authors.initials: EI
authors.lastname: Braicu
authors.forename: Jalid
authors.initials: J
authors.lastname: Sehouli
authors.forename: Marc
authors.initials: M
authors.lastname: Ehlers
authors.forename: Markus
authors.initials: M
authors.lastname: Berger
authors.forename: Rudolf
authors.initials: R
authors.lastname: Tauber
authors.forename: Véronique
authors.initials: V
authors.lastname: Blanchard
mesh_terms: D016022:Case-Control Studies; D019075:Electrophoresis, Capillary / Q000379:methods*; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood* / Q000737:chemistry*; D008745:Methylation; D019158:N-Acetylneuraminic Acid / Q000737:chemistry*; D010051:Ovarian Neoplasms / Q000097:blood* / Q000737:chemistry*; D011134:Polysaccharides / Q000097:blood* / Q000737:chemistry; D006023:Glycoproteins
chemical_list: D007074:Immunoglobulin G; D019158:N-Acetylneuraminic Acid; D011134:Polysaccharides; C046179:glycosylated IgG; D006023:Glycoproteins