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Post-Translational Modification (PTM) - Glycosylation

Reputable Mentor II
Reputable Mentor II


Nearly all proteins undergo chemical modifications after translation. These post-translational modifications (PTMs) play crucial roles in functional proteomics, regulating the protein structure, activity, and expression. PTMs regulate interaction with cellular molecules such as nucleic acids, lipids and cofactors, as well as other proteins. PTMs can occur at any moment in the "life cycle" of a protein, influencing their biological function in processes such as initiating catalytic activity, governing protein-protein interactions, or causing protein degradation. Glycosylation and phosphorylation are of particular interest to researchers because they are critical pathways for signaling, activation, and often give insight into disease states.

Analysis of PTMs by mass spectrometry using multiple fragmentation techniques yields the most comprehensive structural characterization of modified proteins. Here we describe useful workflows for analysis of glycosylated and phosphorylated proteins.

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Workflow Overview for Glycosylation


Glycosylation is likely the most common PTM. It is known to play a role in biochemical processes, ranging from mediation of cell interactions to defining cellular identities within complex tissues.1,2 In addition, glycan structures are unique to the proteins and help to regulate the protein activity. Many glycans undergo disease-related expression level changes, potentially providing critical diagnostic information.3,4 Mass spectrometry (MS) has emerged as one of the most powerful tools for structural elucidation of glycosylations due to its sensitive detection and ability to analyze complex mixtures derived from a variety of organisms and cell lines. Sample enrichment, MS acquisition strategy and data analysis must all be optimized to ensure successful glycoproteomics experiments.







1. The Potentials of Glycomics in Biomarker Discovery

Miura Y, Hato M, et al.
Mol Cell Proteomics. 2008 Feb;7(2):370-7.


2. Glycomics: a pathway to a class of new and improved therapeutics

Shriver Z, Raguram S, et al.
Nat Rev Drug Discov. 2004 Oct;3(10):863-73.

3. Altered Glycosylation of Surface Glycoproteins in Tumor Cells and its Clinical Application

Kobata A.
Pigment Cell Res. 1989 Jul-Aug;2(4):304-8.

4. Glycosylation defining cancer cell motility and invasiveness

Ono M, Hakomori S.
Glycoconj J. 2004;20(1):71-8.

Sample Preparation

Sample Prep Workflow for Glycosylation

Sample enrichment is central to the success of any MS-based glycoproteomics workflow. It reduces the overall complexity of the sample, thereby facilitating sensitive and accurate analysis. For glycoproteomics, the enrichment steps can be carried out at the protein level1-5, peptide level6-13, or at both levels. It can be targeted or universal, depending on the nature of information sought. For example, targeted enrichment of glycopeptides14,15 or glycoproteins may be performed to selectively isolate a certain subset, on the basis of specific glycan structures. Thermo Scientific Pierce Glycoprotein Isolation Kits, Concanavilin A (ConA) and Wheat Germ Agglutinin (WGA) allow isolation of glycoproteins at the protein level from complex mixtures, including serum, tissue and cultured cell lysates. These complete kits contain the immobilized lectins, binding and wash buffers and columns required to process up to 10 mg of total protein. Thermo Scientific HyperSep™ Retain AX Cartridges enable fast and efficient enrichment of glycopeptides. These cartridges are packed with a high capacity, high purity, highly porous polystyrene DVB material partially modified with quaternary amine functional groups thereby providing excellent efficiency for glycopeptide enrichment.



1. Screening for N-glycosylated proteins by liquid chromatography mass spectrometry

Bunkenborg J, Pilch BJ, et al.
Proteomics. 2004 Feb;4(2):454-65.

2. Preparation of a high-performance multi-lectin affinity chromatography (HP-M-LAC) adsorbent for the analysis of human plasma glycoproteins

Kullolli M, Hancock WS, et al.
J Sep Sci. 2008 Aug;31(14):2733-9.

3. Approaches to the study of N-linked glycoproteins in human plasma using lectin affinity chromatog...

Wang Y, Wu SL, et al.
Glycobiology. 2006 Jun;16(6):514-23.

4. Monitoring of glycoprotein products in cell culture lysates using lectin affinity chromatography ...

Wang Y, Wu SL, et al.
Biotechnol Prog. 2006 May-Jun;22(3):873-80.

5. Approach to the comprehensive analysis of glycoproteins isolated from human serum using a multi-l...

Yang Z, Hancock WS.
J Chromatogr A. 2004 Oct 22;1053(1-2😞79-88.

6. Glycopeptide analysis by mass spectrometry

Dalpathado DS, Desaire H.
Analyst. 2008 Jun;133(6):731-8.

7. Method development for HILIC assays

Dejaegher B, Mangelings D, et al.
J Sep Sci. 2008 May;31(9):1438-48.

8. A new strategy for identification of N-glycosylated proteins and unambiguous assignment of their ...

Hägglund P, Bunkenborg J, et al.
J Proteome Res. 2004 May-Jun;3(3):556-66.

9. Differential analysis of site-specific glycans on plasma and cellular fibronectins: application o...

Tajiri M, Yoshida S, et al.
Glycobiology. 2005 Dec;15(12):1332-40.

10. Hydrophilic affinity isolation and MALDI multiple-stage tandem mass spectrometry of glycopeptide...

Wada Y, Tajiri M, et al.
Anal Chem. 2004 Nov 15;76(22):6560-5.

11. Structural glycomics using hydrophilic interaction chromatography (HILIC) with mass spectrometry

Wuhrer M, de Boer AR, et al.
Mass Spectrom Rev. 2009 Mar-Apr;28(2):192-206.

12. Identification and quantification of N-linked glycoproteins using hydrazide chemistry, stable is...

Zhang H, Li XJ, Martin DB, et al.
Nat Biotechnol. 2003 Jun;21(6):660-6.

13. Maximizing coverage of glycosylation heterogeneity in MALDI-MS analysis of glycoproteins with up...

Zhang Y, Go EP, et al.
Anal Chem. 2008 May 1;80(9):3144-58.

14. Exploring the sialiome using titanium dioxide chromatography and mass spectrometry

Larsen MR, Jensen SS, et al.
Mol Cell Proteomics. 2007 Oct;6(10):1778-87.

15. Simple separation of isomeric sialylated N-glycopeptides by a zwitterionic type of hydrophilic i...

Takegawa Y, Deguchi K, et al.
J Sep Sci. 2006 Nov;29(16):2533-40.

Related Products

Pierce Glycoprotein Isolation Kits

HyperSep™ Retain AX Cartridges

Additional resources

SAX for quick and simple enrichment of glycopeptides

Mass Spectrometry

Mass Spectrometry Workflow for Glycosylation

The field of proteomics has benefited tremendously from collisional-activated dissociation (CAD) as this fragmentation technique generates abundant peptide bond cleavages resulting in large number of peptides and protein identifications. However, CAD is not ideal for glycopeptides analysis as this fragmentation does not produce the desired peptide backbone cleavages for sequencing.1 On commercial mass spectrometers CAD fragmentation generates varying degrees of structural information for glycopeptides. Low energy CAD predominantly fragments the glycan on a glycopeptide rather than the peptide, generating spectra that are dominated by glycosidic bond cleavages rather than the desired peptide bond cleavages. Thus, making it very difficult to sequence the glycopeptide.2-5 Further complicating the issue is the cleavage of the peptide-glycan bond, resulting in the loss of information about glycosylation site. The increased collision energy on CAD can generate some peptide backbone fragmentation, but this comes with a complication. It generates mixed MS/MS spectrum where both glycan and peptide information are present making structural interpretation complicated.6 Regardless of whether high- or low-energy CAD is employed, fragmentation of the peptide-glycan bond still occurs limiting the ability to derive information about the site of glycosylation. Electron-transfer dissociation (ETD)7 is far better suited for glycopeptide analyses due to their nonergodic type of dissociation. ETD produces extensive fragmentation of the peptide backbone enabling sequencing of the peptide while preserving glycans on the peptide backbone. This allows for unambiguous assignment of the glycosylation sites, thus providing complementary information to CAD fragmentation. The complementary information provided by ETD along with CAD yields richer glycosylation information than either technique by itself.

Several studies in the past have shown the importance of combining CAD and ETD fragmentation for intact glycopeptides analysis.7-10 However, all of these studies have used both types of fragmentation in a nonselective fashion. We have expanded on this approach to implement an intelligent acquisition strategy termed HCD product-dependent ETD workflow (HCD-pd-ETD) that enables on-the-fly identification of glycopeptides and improves overall productivity of glycopeptide analyses.11-14 In this approach, the mass spectrometer acquires HR/AM HCD spectra in a data-dependent fashion. The instrument identifies glycan oxonium ions on the fly in the HCD spectra and triggers ETD spectra on the glycopeptide precursors only. This results in streamlined data analysis and improvement in dynamic range and duty cycle. The HCD-pd-ETD method is provided within the instrument control software for Orbitrap Fusion and Orbitrap Fusion Lumos mass spectrometers. In addition to HCD-pd-ETD, Orbitrap Fusion and Orbitrap Fusion Lumos MS can trigger any fragmentation based on oxonium ion presence including CID and HCD (HCD-pd-CID, HCD-pd-HCD). Triggering CID fragmentation based on the detection of oxonium ions is useful for elucidating glycan composition information as CID tends to produce more detailed glycan backbone fragmentation. This approach is useful as glycans are heterogeneous PTMs; multiple glycans can be present at a single amino acid site and requires complete characterization of all detected compositions.

Orbitrap Fusion and Orbitrap Fusion Lumos introduced a novel fragmentation referred to as electron-transfer/higher energy collision dissociation (EThcD) that is unique to these platforms. In this fragmentation ETD and HCD are combined in a single spectrum. In EThcD, precursors are fragmented within the linear ion trap using ETD, the precursors, charge reduced precursors and ETD fragment ions are then transferred to the IRM for HCD fragmentation. The result is an EThcD spectrum containing b-, c-, y- and z- ions, a spectrum that is combination of ETD and HCD fragments. Studies have shown that EThcD data provides more complete fragmentation of unmodified and phosphorylated peptides than HCD or ETD alone, and it also increases confidence in localization of phosphorylation sites.15-17 EThcD appears advantageous for glycopeptides, enabling better sequence coverage and glycosylation site localization. It should be noted that EThcD can also be acquired in an HCD-pd- fashion for glycopeptides analysis.

For glycopeptides analysis, LC columns at least 25 cm in length with gradients greater than one hour are recommended.



1. Glycoproteomics based on tandem mass spectrometry of glycopeptides

Wuhrer M, Catalina MI, et al.
J Chromatogr B Analyt Technol Biomed Life Sci. 2007 Apr 15;849(1-2):115-28.

2. High-performance anion-exchange chromatography coupled with mass spectrometry for the determinati...

Conboy JJ, Henion J.
Biol Mass Spectrom. 1992 Aug;21(8):397-407.

3. Collisional fragmentation of glycopeptides by electrospray ionization LC/MS and LC/MS/MS: methods fo...

Huddleston MJ, Bean MF, et al.
Anal Chem. 1993 Apr 1;65(7):877-84.

4. Comparison of HPLC/ESI-FTICR MS versus MALDI-TOF/TOF MS for glycopeptide analysis of a highly gly...

Irungu J, Go EP, et al.
J Am Soc Mass Spectrom. 2008 Aug;19(8):1209-20.

5. Localization of O-glycosylation sites in peptides by electron capture dissociation in a Fourier tran...

Mirgorodskaya E, Roepstorff P, et al.
Anal Chem. 1999 Oct 15;71(20):4431-6.

6. Determination and characterization of site-specific N-glycosylation using MALDI-Qq-TOF tandem mass s...

Bykova NV, Rampitsch C, et al.
Anal Chem. 2006 Feb 15;78(4):1093-103.

7. Electron-capture dissociation tandem mass spectrometry

Zubarev RA.
Curr Opin Biotechnol. 2004 Feb;15(1):12-6.

8. The utility of ETD mass spectrometry in proteomic analysis

Mikesh LM, Ueberheide B, et al.
Biochim Biophys Acta. 2006 Dec;1764(12):1811-22.

9. Characterization of glycopeptides by combining collision-induced dissociation and electron-transf...

Alley Jr. WR, Mechref Y, Novotny MV
Rapid Commun Mass Spectrom 23, 1, 161-170, 2009


10. A simple cellulose column procedure for selective enrichment of glycopeptides and characterizati...

Snovida SI, Bodnar ED, Viner R, Saba J, Perreault H
Carbohydr Res 345, 6, 792-801, 2010

11. Mining the O-glycoproteome using zinc-finger nuclease-glycoengineered SimpleCell lines

Steentoft C, Vakhrushev SY, et al.
Nat Methods. 2011 Oct 9;8(11):977-82.

12. Combining high-energy C-trap dissociation and electron transfer dissociation for protein O-GlcNAc mo...

Zhao P, Viner R, et al.
J Proteome Res. 2011 Sep 2;10(9):4088-104.

13. Increasing the productivity of glycopeptides analysis by using higher-energy collision dissociat...

Saba J, Dutta S, et al.
Int J Proteomics. 2012;2012:560391.

14. Probing isoform-specific functions of polypeptide GalNAc-transferases using zinc finger nuclease...

Schjoldager KT, Vakhrushev SY, et al.
Proc Natl Acad Sci U S A. 2012 Jun 19;109(25):9893-8.

15. Higher energy collision dissociation (HCD) product ion-triggered electron transfer dissociation ...

Singh C, Zampronio C, et al.
J Proteome Res. 2012 Sep 7;11(9):4517-25.

16. Unambiguous phosphosite localization using electron-transfer/higher-energy collision dissociatio...

J Proteome Res 2013 12(3):1520-5.

17. Toward full peptide sequence coverage by dual fragmentation combining electron-transfer and high...

Frese CK, Altelaar AF, van den Toorn H, Nolting D, Griep-Raming J, Heck AJ, Mohammed S
Anal Chem 2012, 84(22):9668-73.

18. Extended O-GlcNAc on HLA Class-I-Bound Peptides

Marino F, Bern M1, Mommen GP2, Leney AC, van Gaans-van den Brink JA3, Bonvin AM, Becker C1, van Els CA3, Heck AJ
J Am Chem Soc 2015, 37(34):10922-5



Orbitrap Fusion Lumos

Orbitrap Fusion

Orbitrap Elite

Thermo Scientific provides UPLC/HPLC systems that perform at low nano, micro, and high flow rate regimes to meet a wide variety of experimental needs.  Thermo Scientific EASY-nLC 1200 and Dionex UltiMate® 3000 RSLCnano LC systems use split-free designs to achieve exceptional stability and reproducibility and they easily couple to all Thermo Scientific mass spectrometers.

Additional resources

Orbitrap Fusion MS for Glycan and Glycopeptide Analysis

Saba J.
White Paper

Novel LC-MS2 Product Dependent Parallel Data Acquisition Function and Data Analysis Workflow for Seq...

Wu S, Pu T, Viner R and Khoo KH
Anal. Chem., 2014, 86 (11), pp 5478–5486

Fragmentation Patterns of EThcD Spectra of Phosphopeptides and Glycopeptides

Bern M, Kil YJ, Tang W, Becker C, Frese CK, Altelaar M, Mohammed S, Heck AJR, Syka J, Bomgarden R, Viner R.
ASMS 2013 Poster

Data Analysis

Data Analysis Workflow for Glycosylation

In recent years, much emphasis has been placed on developing bioinformatics tools to simplify interpretation of glycopeptides MSn data. The recent development of a novel software tool, ByonicTM from Protein Metrics, alleviates a lot of the hurdles accompanying manual interpretation. Byonic software utilizes data from both types of fragmentation: HCD data to identify the sugar composition and the corresponding ETD data for peptide backbone information. The final result describes the peptide sequence, site of glycosylation and the glycan composition. Additionally, Byonic also supports the interpretation of EThcD data.

Visit the Protein Metrics website to learn more about Byonic software.

Grant Central

Grant Central Resources for Glycosylation

Every research idea matters. At Thermo Fisher Scientific, we are dedicated to helping you advance your research, and that includes becoming your scientific partner in supporting your grant application efforts.  Our latest grant writing resources are listed below.

Need supporting information for your grant proposal or have a grant writing related question? Visit Grant Central or  Contact Us.

GENERAL Resources


Top 5 reasons to upgrade from a Thermo Scientific™ Hybrid Orbitrap™ to a Thermo Scientific™ Tribrid™...
Grant Application Resource

Technical Resources


Comprehensive Characterization of Proteins using a Novel Orbitrap Tribrid Mass Spectrometer — The Ga...
Presentation with Speaker Notes

Thermo Scientific Guide to Glycan Analysis

Technical Guide

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Last update:
‎10-15-2021 05:46 AM
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