title: Structural characterization of the oligosaccharide chains of human alpha1-microglobulin from urine and amniotic fluid.
abstract: Human alpha1-microglobulin (alpha1-m; also called protein HC), a glycoprotein belonging to the lipocalin superfamily, was isolated by sequential anion-exchange chromatography and gel filtration from the urine of hemodialized patients and from amniotic fluid collected in the week 16-18 of pregnancy. The carbohydrate chains of the protein purified from the two sources, which are organized in two Asn-linked and one Thr-linked oligosaccharides, were structurally characterized using matrix-assisted laser desorption ionization and electrospray mass spectrometry. The glycans attached to Thr5 are differently truncated NeuHexHexNAc sequences, and O-glycosylation in the amniotic fluid protein is only partial. Asn96 has both diantennary and triantennary structures attached in the case of urinary alpha1-m and only diantennary glycans in the amniotic fluid protein. The main carbohydrate units attached to Asn17 are in both proteins monosialylated and disialylated diantennary glycans. The position of the oligosaccharide chains in a three-dimensional model of the protein, produced using the automated Swiss-Model service, is also discussed.
authors.affiliation: Centro Internazionale di Servizi di Spettrometria di Massa e Dipartimento di Chimica Organica e Biologica, Università di Napoli, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Amoresano
authors.forename: L
authors.initials: L
authors.lastname: Minchiotti
authors.forename: M E
authors.initials: ME
authors.lastname: Cosulich
authors.forename: M
authors.initials: M
authors.lastname: Campagnoli
authors.forename: P
authors.initials: P
authors.lastname: Pucci
authors.forename: A
authors.initials: A
authors.lastname: Andolfo
authors.forename: E
authors.initials: E
authors.lastname: Gianazza
authors.forename: M
authors.initials: M
authors.lastname: Galliano
mesh_terms: D000510:Alpha-Globulins / Q000032:analysis / Q000737:chemistry* / Q000276:immunology / Q000652:urine; D000653:Amniotic Fluid / Q000737:chemistry*; D000911:Antibodies, Monoclonal / Q000276:immunology; D002236:Carbohydrate Conformation; D002851:Chromatography, High Pressure Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D006801:Humans; D008958:Models, Molecular; D011134:Polysaccharides / Q000737:chemistry*; D011247:Pregnancy; D017434:Protein Structure, Tertiary; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D000510:Alpha-Globulins; D000911:Antibodies, Monoclonal; D011134:Polysaccharides; C016001:alpha-1-microglobulin