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Hong Q, Ruhaak LR, Stroble C, Parker E, Huang J, Maverakis E, Lebrilla CB. A Method for Comprehensive Glycosite-Mapping and Direct Quantitation of Serum Glycoproteins. J Proteome Res 2015; 14:5179-92. [PMID: 26510530 DOI: 10.1021/acs.jproteome.5b00756] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
A comprehensive glycan map was constructed for the top eight abundant glycoproteins in plasma using both specific and nonspecific enzyme digestions followed by nano liquid chromatography (LC)-chip/quadrupole time-of-flight mass spectrometry (MS) analysis. Glycopeptides were identified using an in-house software tool, GPFinder. A sensitive and reproducible multiple reaction monitoring (MRM) technique on a triple quadrupole MS was developed and applied to quantify immunoglobulins G, A, M, and their site-specific glycans simultaneously and directly from human serum/plasma without protein enrichments. A total of 64 glycopeptides and 15 peptides were monitored for IgG, IgA, and IgM in a 20 min ultra high performance (UP)LC gradient. The absolute protein contents were quantified using peptide calibration curves. The glycopeptide ion abundances were normalized to the respective protein abundances to separate protein glycosylation from protein expression. This technique yields higher method reproducibility and less sample loss when compared with the quantitation method that involves protein enrichments. The absolute protein quantitation has a wide linear range (3-4 orders of magnitude) and low limit of quantitation (femtomole level). This rapid and robust quantitation technique, which provides quantitative information for both proteins and glycosylation, will further facilitate disease biomarker discoveries.
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Affiliation(s)
- Qiuting Hong
- Department of Chemistry and ‡Department of Dermatology, School of Medicine, University of California , Davis, California 95616, United States
| | - L Renee Ruhaak
- Department of Chemistry and ‡Department of Dermatology, School of Medicine, University of California , Davis, California 95616, United States
| | - Carol Stroble
- Department of Chemistry and ‡Department of Dermatology, School of Medicine, University of California , Davis, California 95616, United States
| | - Evan Parker
- Department of Chemistry and ‡Department of Dermatology, School of Medicine, University of California , Davis, California 95616, United States
| | - Jincui Huang
- Department of Chemistry and ‡Department of Dermatology, School of Medicine, University of California , Davis, California 95616, United States
| | - Emanual Maverakis
- Department of Chemistry and ‡Department of Dermatology, School of Medicine, University of California , Davis, California 95616, United States
| | - Carlito B Lebrilla
- Department of Chemistry and ‡Department of Dermatology, School of Medicine, University of California , Davis, California 95616, United States
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