title: Glycoproteomics of milk: differences in sugar epitopes on human and bovine milk fat globule membranes.
abstract: Oligosaccharides from human and bovine milk fat globule membranes were analyzed by LC-MS and LC-MS/MS. Global release of N-linked and O-linked oligosaccharides showed both to be highly sialylated, with bovine peak-lactating milk O-linked oligosaccharides presenting as mono- and disialylated core 1 oligosaccharides (Galbeta1-3GalNAcol), while human milk had core type 2 oligosaccharides (Galbeta1-3(GlcNAcbeta1-6)GalNAcol) with sialylation on the C-3 branch. The C-6 branch of these structures was extended with branched and unbranched N-acetyllactosamine units terminating in blood group H and Lewis type epitopes. These epitopes were also presented on the reducing terminus of the human, but not the bovine, N-linked oligosaccharides. The O-linked structures were found to be attached to the high molecular mass mucins isolated by agarose-polyacrylamide composite gel electrophoresis, where MUC1 and MUC4 were present. Analysis of bovine colostrum showed that O-linked core 2 oligosaccharides are present at the early stage (3 days after birth) but are down-regulated as lactation develops. This data indicates that human milk may provide different innate immune protection against pathogens compared to bovine milk, as evidenced by the presence of Lewis b epitope, a target for the Helicobacter pylori bacteria, on human, but not bovine, milk fat globule membrane mucins. In addition, non-mucin-type O-linked fucosylated oligosaccharides were found (NeuAc-Gal-GlcNAc1-3Fuc-ol in bovine milk and Gal-GlcNAc1-3Fuc-ol in human milk). The O-linked fucose structure in human milk is the first to our knowledge to be found on high molecular mass mucin-type molecules.
authors.affiliation: Proteome Systems Limited, Locked Bag 2073, North Ryde, Sydney, NSW 1670, Australia.
authors.forename: Nicole L
authors.initials: NL
authors.lastname: Wilson
authors.forename: Leanne J
authors.initials: LJ
authors.lastname: Robinson
authors.forename: Anne
authors.initials: A
authors.lastname: Donnet
authors.forename: Lionel
authors.initials: L
authors.lastname: Bovetto
authors.forename: Nicolle H
authors.initials: NH
authors.lastname: Packer
authors.forename: Niclas G
authors.initials: NG
authors.lastname: Karlsson
mesh_terms: D000818:Animals; D002417:Cattle; D002853:Chromatography, Liquid; D004587:Electrophoresis, Agar Gel; D004591:Electrophoresis, Polyacrylamide Gel; D000939:Epitopes / Q000737:chemistry*; D005223:Fats / Q000032:analysis*; D005260:Female; D006031:Glycosylation; D006801:Humans; D007774:Lactation; D008892:Milk / Q000737:chemistry*; D009077:Mucins / Q000032:analysis; D009844:Oligosaccharides / Q000737:chemistry*; D040901:Proteomics; D053719:Tandem Mass Spectrometry
chemical_list: D000939:Epitopes; D005223:Fats; D009077:Mucins; D009844:Oligosaccharides