Glyco

Title : Comprehensive glyco-proteomic analysis of human alpha1-antitrypsin and its charge isoforms

Abstract :

Human alpha1-antitrypsin ( A1PI ) is a well-known glycoprotein in human plasma important for the protection of tissues from proteolytic enzymes
The three N-glycosylation sites of A1PI contain diantennary N-glycans but also triantennary and even traces of tetraantennary structures leading to the typical IEF pattern observed for A1PI
Here we present an approach to characterize A1PI isoforms from human plasma and its PTMs by LC- ESI-MS and LC- ESI-MS/MS of peptides obtained by proteolytic digestion
The single cysteine residue of A1PI formed a disulfide bridge with free cysteine
The variability of the number of antennae and hence sialic acids on glycosylation site N107 , which even contained minute amounts of tetraantennary structures, emerged as a major cause for the IEF pattern of A1PI
Only negligible amounts of triantennary structures were identified attached to N70 , and exclusively diantennary structures were present on site N271 in each of the isoforms analyzed
Exoglycosidase digests revealed alpha2,6-linked neuraminic acids on diantennary N-glycans, and triantennary contained additionally one single alpha2,3-neuraminic acid per N-glycan, which, together with a fucose, formed a sialyl Lewis X determinant on the beta1,4-linked N-acetylglucosamine, as shown by 2-D-HPLC of pyridylaminated asialoglycans
Fucosylation of diantennary structures was marginal and of the core alpha1,6 type

Output (sent_index, trigger, protein, sugar, site):

1. glycoprotein, , Human alpha1-antitrypsin, -, -
1. glycoprotein, , glycoprotein, -, -
2. N-glycosylation, , A1PI, -, sites
2. contain, , A1PI, diantennary N-glycans but also triantennary and even traces, sites
5. acids, , -, glycosylation site N107, site N107
5. antennae, , -, glycosylation site N107, site N107
5. glycosylation, , -, -, site N107
6. attached, , -, triantennary structures, N70
6. present, , -, exclusively diantennary structures, site N271
6. present, , isoforms, exclusively diantennary structures, site N271
8. Fucosylation, , -, diantennary structures, -

Output(Part-Of) (sent_index, protein, site):

*Output_Site_Fusion* (sent_index, protein, sugar, site):