title: iTRAQ plus 18O: a new technique for target glycoprotein analysis.
abstract: A novel strategy combining iTRAQ with (18)O stable isotope labeling (iTRAQ plus (18)O) was established to identify N-glycosylation site, quantify the glycopeptides and non-glycosylated peptides, and obtain N-glycosylation site ratio on the target glycoprotein. In this approach, all peptides of four biological samples are labeled with four iTRAQ reagents in parallel, followed by PNGase F catalyzed labeling of N-glycosylation sites with H(2)(16)O and H(2)(18)O. Two sample groups are labeled with H(2)(16)O and the other two are labeled with H(2)(18)O. After the modification of MS precursor ion isolation window, tagged peptides are identified by LC-MS/MS, both glycopeptides and non-glycopeptides are quantified simultaneously using ProteinPilot™ Software. With four samples to be maximally analyzed in parallel, this workflow supports accurate identification and quantification of glycopeptides in a site-specific fashion. Furthermore, N-glycosylation site ratios on serum haptoglobin (Hp) β chain in healthy individuals as well as patients with hepatitis B virus (HBV), liver cirrhosis (LC) and hepatocellular carcinoma (HCC) were quantified to validate the novel 'iTRAQ plus (18)O' method. Glycosite ratios of VVLHPN#YSQVDIGLIK were observed to change significantly in HCC patients compared with LC and HBV patients. This novel approach supports the screening of the target glycoproteins as biomarkers in clinical application.
authors.affiliation: Liver Cancer Institute, Zhongshan Hospital, Key Laboratory of Carcinogenesis and Cancer Invasion (Fudan University), Ministry of Education, Shanghai, PR China.
authors.forename: Shu
authors.initials: S
authors.lastname: Zhang
authors.forename: Xiaohui
authors.initials: X
authors.lastname: Liu
authors.forename: Xiaonan
authors.initials: X
authors.lastname: Kang
authors.forename: Chun
authors.initials: C
authors.lastname: Sun
authors.forename: Haojie
authors.initials: H
authors.lastname: Lu
authors.forename: Pengyuan
authors.initials: P
authors.lastname: Yang
authors.forename: Yinkun
authors.initials: Y
authors.lastname: Liu
mesh_terms: D001665:Binding Sites; D015415:Biomarkers; D006023:Glycoproteins / Q000737:chemistry*; D006031:Glycosylation; D006509:Hepatitis B; D006526:Hepatitis C; D006801:Humans; D007553:Isotope Labeling / Q000379:methods*; D010103:Oxygen Isotopes
chemical_list: D015415:Biomarkers; D006023:Glycoproteins; D010103:Oxygen Isotopes