Carbohydrate moieties in human secretory component.
Human secretory component has seven putative sites for N-linked glycosylation. From tryptic and Glu-C digests we have isolated peptides encompassing asparagines 65, 72, 117, 168, 403, 451 and 481. Analysis by on line HPLC-electrospray mass spectrometry indicated that these residues were fully glycosylated and that the major carbohydrate moieties were far less diversified in composition than expected. Fast atom bombardment mass spectrometry performed on oligosaccharides released by peptide-N-glycosidase F treatment of fractionated and unfractionated SC digests showed the following glycan compositions: Fuc(2)Hex(5)HexNAc(4), Fuc(3)Hex(5)HexNAc(4), NeuAcFucHex(5)HexNAc(4), NeuAcFuc(2)Hex(5)HexNAc(4), NeuAc(2)Hex(5)HexNAc4 and NeuAc(2)FucHex(5)HexNAc(4). Three of these oligosaccharides are the major carbohydrate moieties in human lactoferrin. A possible biological role of the secretory component glycans in the protection of mucosal surfaces is discussed.
Hughes
G J
GJ
Department of Medical Biochemistry at the Medical Center, Faculty of Medicine, University of Geneva, 1 rue Michel-Servet, CH-1211, Geneva, Switzerland. hughes@cmu.unige.ch
Reason
A J
AJ
Savoy
L
L
Jaton
J
J
Frutiger-Hughes
S
S
D000595:Amino Acid Sequence; D002240:Carbohydrate Sequence; D002241:Carbohydrates / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid; D006020:Glycopeptides / Q000737:chemistry; D006801:Humans; D013058:Mass Spectrometry / Q000379:methods; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000737:chemistry; D010449:Peptide Mapping; D012635:Secretory Component / Q000737:chemistry* / Q000302:isolation & purification; D012697:Serine Endopeptidases; D014357:Trypsin
D002241:Carbohydrates; D006020:Glycopeptides; D009844:Oligosaccharides; D012635:Secretory Component; D012697:Serine Endopeptidases; C028344:glutamyl endopeptidase; D014357:Trypsin