Primary structure of the N-glycosidically linked sialoglycans of secretory immunoglobulins A from human milk.
The alkali-stable sialoglycopeptides of secretory immunoglobulins A from human milk have been separated from the alkali-labile glycopeptides by gel filtration and from the asialoglycopeptides by ion-exchange chromatography. The structures of five of them have been determined on the basis of the results obtained by methylation analysis, mass spectrometry and 360 MHz 1H-NMR spectroscopy. For glycopeptide B, the following structure has been found: (formula; see text) The other glycopeptides can be considered as extensions of this structure. The following extensions to Gal-6' are proposed: NeuAc(alpha 2-6) (glycopeptide A), Gal(beta 1-3) (glycopeptide D) and Fuc(alpha 1-6) (glycopeptide E). Furthermore, in glycopeptide C a fucose residue in (alpha 1-3) linkage to GlcNAc-5' could be traced.
D000468:Alkalies; D055598:Chemical Phenomena; D002621:Chemistry; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D006027:Glycosides / Q000302:isolation & purification*; D006801:Humans; D007070:Immunoglobulin A / Q000302:isolation & purification*; D007071:Immunoglobulin A, Secretory / Q000302:isolation & purification*; D008895:Milk, Human / Q000276:immunology*; D012795:Sialoglycoproteins / Q000302:isolation & purification*
D000468:Alkalies; D006027:Glycosides; D007070:Immunoglobulin A; D007071:Immunoglobulin A, Secretory; D012795:Sialoglycoproteins