title: Glycoproteomic characterization of butyrylcholinesterase from human plasma.
abstract: Human butyrylcholinesterase (hBChE) is a highly glycosylated protein present in human plasma. The enzyme hydrolyses choline esters, for example benzoylcholine, butyrylthiocholine and acetylthiocholine as well as noncholine esters like heroin and aspirin. hBChE is primarily involved in neuronal transmission and is a potential bioscavenger of toxic organophosphates to protect acetylcholinesterase. A prerequisite for the therapeutic use of hBChE is a detailed characterization of this glycoprotein purified from human plasma. In this study, MS/MS could confirm most of the protein backbone, including the N- and the C-terminus. Site-specific analysis of all nine potential N-glycosylation sites revealed mainly mono- and disialylated N-glycans to be present on this glycoprotein. Sialic acids (Neu5Ac) are mainly alpha2,6-linked, however a fraction of the N-glycans contained Neu5Ac also in alpha2,3 linkage. On monosialylated N-glycans, sialic acid is exclusively located on the 3-arm and in alpha2,6 linkage, as verified by 2D-HPLC and exoglycosidase digests of 2-aminopyridine (PA)-labelled N-glycans. This first comprehensive glycoproteomic analysis of the important human plasma glycoprotein BChE did not give any indication of O-glycosylation or any other kind of PTMs as previously postulated.
authors.affiliation: Biochemistry Division, Department of Chemistry, University of Natural Resources and Applied Life Sciences, Vienna, Austria. daniel.kolarich@mq.edu.au
authors.forename: Daniel
authors.initials: D
authors.lastname: Kolarich
authors.forename: Alfred
authors.initials: A
authors.lastname: Weber
authors.forename: Martin
authors.initials: M
authors.lastname: Pabst
authors.forename: Johannes
authors.initials: J
authors.lastname: Stadlmann
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Teschner
authors.forename: Hartmut
authors.initials: H
authors.lastname: Ehrlich
authors.forename: Hans-Peter
authors.initials: HP
authors.lastname: Schwarz
authors.forename: Friedrich
authors.initials: F
authors.lastname: Altmann
mesh_terms: D000595:Amino Acid Sequence; D002091:Butyrylcholinesterase / Q000097:blood*; D002240:Carbohydrate Sequence; D002853:Chromatography, Liquid; D006023:Glycoproteins / Q000737:chemistry*; D006026:Glycoside Hydrolases / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D025942:Oligosaccharides, Branched-Chain; D011134:Polysaccharides / Q000737:chemistry; D040901:Proteomics / Q000379:methods*
chemical_list: D006023:Glycoproteins; D025942:Oligosaccharides, Branched-Chain; D011134:Polysaccharides; D002091:Butyrylcholinesterase; D006026:Glycoside Hydrolases