Open AccessStructural characterization of the oligosaccharide chains of human α 1 ‐microglobulin from urine and amniotic fluid
Author(s) -
Amoresano Angela,
Minchiotti Lorenzo,
Cosulich Maria E.,
Campagnoli Monica,
Pucci Piero,
Andolfo Annapaola,
Gianazza Elisabetta,
Galliano Monica
Publication year - 2000
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1046/j.1432-1327.2000.01217.x
Subject(s) - amniotic fluid , chemistry , glycan , glycoprotein , oligosaccharide , chromatography , mass spectrometry , lipocalin , biochemistry , biology , fetus , pregnancy , genetics
Human α 1 ‐microglobulin (α 1 ‐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 α 1 ‐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.