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Rajczewski A, Ndreu L, Vryonidis E, Hurben AK, Jamshidi S, Griffin TJ, Törnqvist MÅ, Tretyakova NY, Karlsson I. Mass Spectrometry-Based Strategies for Assessing Human Exposure Using Hemoglobin Adductomics. Chem Res Toxicol 2023; 36:2019-2030. [PMID: 37963067 PMCID: PMC10731639 DOI: 10.1021/acs.chemrestox.3c00294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 10/23/2023] [Accepted: 10/30/2023] [Indexed: 11/16/2023]
Abstract
Hemoglobin (Hb) adducts are widely used in human biomonitoring due to the high abundance of hemoglobin in human blood, its reactivity toward electrophiles, and adducted protein stability for up to 120 days. In the present paper, we compared three methods of analysis of hemoglobin adducts: mass spectrometry of derivatized N-terminal Val adducts, mass spectrometry of N-terminal adducted hemoglobin peptides, and limited proteolysis mass spectrometry . Blood from human donors was incubated with a selection of contact allergens and other electrophiles, after which hemoglobin was isolated and subjected to three analysis methods. We found that the FIRE method was able to detect and reliably quantify N-terminal adducts of acrylamide, acrylic acid, glycidic acid, and 2,3-epoxypropyl phenyl ether (PGE), but it was less efficient for 2-methyleneglutaronitrile (2-MGN) and failed to detect 1-chloro-2,4-dinitrobenzene (DNCB). By contrast, bottom-up proteomics was able to determine the presence of adducts from all six electrophiles at both the N-terminus and reactive hemoglobin side chains. Limited proteolysis mass spectrometry, studied for four contact allergens (three electrophiles and a metal salt), was able to determine the presence of covalent hemoglobin adducts with one of the three electrophiles (DNCB) and coordination complexation with the nickel salt. Together, these approaches represent complementary tools in the study of the hemoglobin adductome.
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Affiliation(s)
- Andrew
T. Rajczewski
- Department
of Biochemistry, University of Minnesota, Minneapolis, Minnesota55455, United States
| | - Lorena Ndreu
- Department
of Environmental Science, Stockholm University, SE-10691Stockholm, Sweden
| | - Efstathios Vryonidis
- Department
of Environmental Science, Stockholm University, SE-10691Stockholm, Sweden
| | - Alexander K. Hurben
- Department
of Medicinal Chemistry and the Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota55455, United States
| | - Sara Jamshidi
- Department
of Environmental Science, Stockholm University, SE-10691Stockholm, Sweden
| | - Timothy J. Griffin
- Department
of Biochemistry, University of Minnesota, Minneapolis, Minnesota55455, United States
| | | | - Natalia Y. Tretyakova
- Department
of Medicinal Chemistry and the Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota55455, United States
| | - Isabella Karlsson
- Department
of Environmental Science, Stockholm University, SE-10691Stockholm, Sweden
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2
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Ndreu L, Hurben AK, Nyman GSA, Tretyakova NY, Karlsson I, Hagvall L. Investigation into Propolis Components Responsible for Inducing Skin Allergy: Air Oxidation of Caffeic Acid and Its Esters Contribute to Hapten Formation. Chem Res Toxicol 2023. [PMID: 37184291 DOI: 10.1021/acs.chemrestox.2c00386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Propolis is a resin-like material produced by bees from the buds of poplar and cone-bearing trees and is used in beehive construction. Propolis is a common additive in various biocosmetics and health-related products, despite the fact that it is a well-known cause of contact allergy. Caffeic acid and its esters have been the primary suspects behind the sensitization potency of propolis-induced contact allergy. However, the chemical structures of the protein adducts formed between these haptens and skin proteins during the process of skin sensitization remain unknown. In this study, the reactivity of three main contact allergens found in propolis, namely, caffeic acid (CA), caffeic acid 1,1-dimethylallyl ester (CAAE), and caffeic acid phenethyl ester (CAPE), was investigated. These compounds were initially subjected to the kinetic direct peptide reactivity assay to categorize the sensitization potency of CA, CAAE, and CAPE, but the data obtained was deemed too unreliable to confidently classify their skin sensitization potential based on this assay alone. To further investigate the chemistry involved in generating possible skin allergy-inducing protein adducts, model peptide reactions with CA, CAAE, and CAPE were conducted and analyzed via liquid chromatography-high-resolution mass spectrometry. Reactions between CA, CAAE, and CAPE and a cysteine-containing peptide in the presence of oxygen, both in closed and open systems, were monitored at specific time points. These studies revealed the formation of two different adducts, one corresponding to thiol addition to the α,β-unsaturated carbonyl region of the caffeic structure and the second corresponding to thiol addition to the catechol, after air oxidation to o-quinone. Observation of these peptide adducts classifies these compounds as prehaptens. Interestingly, no adduct formation was observed when the same reactions were performed under oxygen-free conditions, highlighting the importance of air oxidation processes in CA, CAAE, and CAPE adduct formation. Additionally, through NMR analysis, we found that thiol addition occurs at the C-2 position in the aromatic ring of the CA derivatives. Our results emphasize the importance of air oxidation in the sensitization potency of propolis and shed light on the chemical structures of the resultant haptens which could trigger allergic reactions in vivo.
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Affiliation(s)
- Lorena Ndreu
- Department of Environmental Science, Stockholm University, Stockholm 114 19, Sweden
| | - Alexander K Hurben
- Department of Medicinal Chemistry and the Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Gunnar S A Nyman
- Department of Dermatology and Venereology, Sahlgrenska University Hospital, Region Västra Götaland, Gothenburg 413 45, Sweden
- Department of Dermatology and Venereology, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg 405 30, Sweden
| | - Natalia Y Tretyakova
- Department of Medicinal Chemistry and the Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Isabella Karlsson
- Department of Environmental Science, Stockholm University, Stockholm 114 19, Sweden
| | - Lina Hagvall
- Department of Dermatology and Venereology, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg 405 30, Sweden
- Department of Occupational and Environmental Medicine, Lund University, Lund 22363, Sweden
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3
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Karlsson I, Ponting DJ, Ortega MA, Niklasson IB, Ndreu L, Stéen EJL, Seifert T, Luthman K, Karlberg AT. Nature-Derived Epoxy Resin Monomers with Reduced Sensitizing Capacity─Isosorbide-Based Bis-Epoxides. Chem Res Toxicol 2023; 36:281-290. [PMID: 36652206 PMCID: PMC9945177 DOI: 10.1021/acs.chemrestox.2c00347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Epoxy resin systems (ERSs) are a class of thermosetting resins that become thermostable and insoluble polymers upon curing. They are widely used as components of protective surfaces, adhesives, and paints and in the manufacturing of composites in the plastics industry. The diglycidyl ether of bisphenol A (DGEBA) is used in 75-90% of ERSs and is thus by far the most used epoxy resin monomer (ERM). Unfortunately, DGEBA is a strong skin sensitizer and it is one of the most common causes of occupational contact dermatitis. Furthermore, DGEBA is synthesized from bisphenol A (BPA), which is a petroleum-derived chemical with endocrine-disruptive properties. In this work, we have used isosorbide, a renewable and nontoxic sugar-based material, as an alternative to BPA in the design of ERMs. Three different bis-epoxide isosorbide derivatives were synthesized: the diglycidyl ether of isosorbide (1) and two novel isosorbide-based bis-epoxides containing either a benzoic ester (2) or a benzyl ether linkage (3). Assessment of the in vivo sensitizing potency of the isosorbide bis-epoxides in the murine local lymph node assay (LLNA) showed that all three compounds were significantly less sensitizing than DGEBA, especially 2 which was nonsensitizing up to 25% w/v. The peptide reactivity showed the same order of reactivity as the LLNA, i.e., 2 being the least reactive, followed by 3 and then 1, which displayed similar peptide reactivity as DGEBA. Skin permeation of 2 and 3 was compared to DGEBA using ex vivo pig skin and static Franz cells. The preliminary investigations of the technical properties of the polymers formed from 1-3 were promising. Although further investigations of the technical properties are needed, all isosorbide bis-epoxides have the potential to be less sensitizing renewable replacements of DGEBA, especially 2 that had the lowest sensitizing potency in vivo as well as the lowest peptide reactivity.
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Affiliation(s)
- Isabella Karlsson
- Department of Environmental Science, Exposure and Effect, Stockholm University, SE-106 91Stockholm, Sweden
| | - David J Ponting
- Department of Chemistry and Molecular Biology, Dermatochemistry and Skin Allergy, University of Gothenburg, SE-412 96Gothenburg, Sweden
| | - Miguel A Ortega
- Department of Chemistry and Molecular Biology, Dermatochemistry and Skin Allergy, University of Gothenburg, SE-412 96Gothenburg, Sweden
| | - Ida B Niklasson
- Department of Chemistry and Molecular Biology, Dermatochemistry and Skin Allergy, University of Gothenburg, SE-412 96Gothenburg, Sweden
| | - Lorena Ndreu
- Department of Environmental Science, Exposure and Effect, Stockholm University, SE-106 91Stockholm, Sweden
| | - E Johanna L Stéen
- Department of Chemistry and Molecular Biology, Dermatochemistry and Skin Allergy, University of Gothenburg, SE-412 96Gothenburg, Sweden
| | - Tina Seifert
- Department of Chemistry and Molecular Biology, Medicinal Chemistry, University of Gothenburg, SE-412 96Gothenburg, Sweden
| | - Kristina Luthman
- Department of Chemistry and Molecular Biology, Medicinal Chemistry, University of Gothenburg, SE-412 96Gothenburg, Sweden
| | - Ann-Therese Karlberg
- Department of Chemistry and Molecular Biology, Dermatochemistry and Skin Allergy, University of Gothenburg, SE-412 96Gothenburg, Sweden
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Ndreu L, Sasse S, Karlberg AT, Karlsson I. Haptenation of Macrophage Migration Inhibitory Factor: A Potential Biomarker for Contact Hypersensitivity. Front Toxicol 2022; 4:856614. [PMID: 35465102 PMCID: PMC9019732 DOI: 10.3389/ftox.2022.856614] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Accepted: 03/03/2022] [Indexed: 11/13/2022] Open
Abstract
The immunological response in contact hypersensitivity is incited by small electrophilic compounds, known as haptens, that react with endogenous proteins after skin absorption. However, the identity of hapten-modified proteins seen as immunogenic remains as yet largely unknown. In a recent study, we have for the first time identified a hapten-modified protein in the local lymph nodes of mice treated topically with the model hapten tetramethylrhodamine isothiocyanate (TRITC). The TRITC modification was located on the N-terminal proline of the protein macrophage migration inhibitory factor (MIF). The focus of the current study was to investigate the presence of the same hapten-protein conjugate in blood samples from mice treated topically with TRITC. Furthermore, TRITC modifications of the two major blood proteins, namely hemoglobin (Hb) and albumin (Alb), as well as TRITC modifications of MIF other than the N-terminal proline, were examined. Following incubation with different molar ratios of TRITC, a proteomic approach was applied to characterize conjugate formation of the three aforementioned proteins, using high resolution mass spectrometry (HRMS). The targeted screening of the TRITC-treated mice blood and lymph node samples for these sites led to the identification of only the same TRITC-MIF conjugate previously detected in the lymph nodes. No Hb and Alb conjugates were detected. Quantification of both the TRITC-modified and unmodified N-terminal peptide of MIF in blood and lymph node samples gave interesting insights of MIF’s role in murine contact hypersensitivity. Incubation of MIF with four different haptens encompassing different reactivity mechanisms and potencies, showed adduct formation at different amino acid residues, suggesting that MIF can be the preferred target for a wide variety of haptens. The present study provides essential progress toward understanding of hapten-protein conjugate formation in contact hypersensitivity and identifies hapten-modified MIF as a potential biomarker for this condition. Further investigation of MIF as a target protein can be a next step to determine if MIF is a biomarker that can be used to develop better diagnostic tools and targeted therapeutics for individuals with allergic contact dermatitis.
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Affiliation(s)
- Lorena Ndreu
- Department of Environmental Science, Stockholm University, Stockholm, Sweden
| | - Samantha Sasse
- Department of Environmental Science, Stockholm University, Stockholm, Sweden
| | - Ann-Therese Karlberg
- Department of Chemistry and Molecular Biology, Dermatochemistry, University of Gothenburg, Gothenburg, Sweden
| | - Isabella Karlsson
- Department of Environmental Science, Stockholm University, Stockholm, Sweden
- *Correspondence: Isabella Karlsson,
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5
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Rajczewski AT, Ndreu L, Pujari SS, Griffin TJ, Törnqvist MÅ, Karlsson I, Tretyakova NY. Novel 4-Hydroxybenzyl Adducts in Human Hemoglobin: Structures and Mechanisms of Formation. Chem Res Toxicol 2021; 34:1769-1781. [PMID: 34110810 PMCID: PMC10159211 DOI: 10.1021/acs.chemrestox.1c00111] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Humans are exposed to large numbers of electrophiles from their diet, the environment, and endogenous physiological processes. Adducts formed at the N-terminal valine of hemoglobin are often used as biomarkers of human exposure to electrophilic compounds. We previously reported the formation of hemoglobin N-terminal valine adducts (added mass, 106.042 Da) in the blood of human smokers and nonsmokers and identified their structure as 4-hydroxybenzyl-Val. In the present work, mass spectrometry-based proteomics was utilized to identify additional sites for 4-hydroxybenzyl adduct formation at internal nucleophilic amino acid side chains within hemoglobin. Hemoglobin isolated from human blood was treated with para-quinone methide (para-QM) followed by global nanoLC-MS/MS and targeted nanoLC-MS/MS to identify amino acid residues containing the 4-hydroxybenzyl modification. Our experiments revealed the formation of 4-hydroxybenzyl adducts at the αHis20, αTyr24, αTyr42, αHis45, βSer72, βThr84, βThr87, βSer89, βHis92, βCys93, βCys112, βThr123, and βHis143 residues (in addition to N-terminal valine) through characteristic MS/MS spectra. These amino acid side chains had variable reactivity toward para-QM with αHis45, αTyr42, βCys93, βHis92, and βSer72 forming the largest numbers of adducts upon exposure to para-QM. Two additional mechanisms for formation of 4-hydroxybenzyl adducts in humans were investigated: exposure to 4-hydroxybenzaldehyde (4-HBA) followed by reduction and UV-mediated reactions of hemoglobin with tyrosine. Exposure of hemoglobin to a 5-fold molar excess of 4-HBA followed by reduction with sodium cyanoborohydride produced 4-hydroxybenzyl adducts at several amino acid side chains of which αHis20, αTyr24, αTyr42, αHis45, βSer44, βThr84, and βHis92 were verified in targeted mass spectrometry experiments. Similarly, exposure of human blood to ultraviolet radiation produced 4-hydroxybenzyl adducts at αHis20, αTyr24, αTyr42, αHis45, βSer44, βThr84, and βSer89. Overall, our results reveal that 4-hydroxybenzyl adducts form at multiple nucleophilic sites of hemoglobin and that para-QM is the most likely source of these adducts in humans.
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Affiliation(s)
- Andrew T Rajczewski
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Lorena Ndreu
- Department of Environmental Science, Stockholm University, Stockholm SE-106 91, Sweden
| | - Suresh S Pujari
- Department of Medicinal Chemistry and the Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Timothy J Griffin
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Margareta Å Törnqvist
- Department of Environmental Science, Stockholm University, Stockholm SE-106 91, Sweden
| | - Isabella Karlsson
- Department of Environmental Science, Stockholm University, Stockholm SE-106 91, Sweden
| | - Natalia Y Tretyakova
- Department of Medicinal Chemistry and the Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota 55455, United States
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6
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Ndreu L, Erber LN, Törnqvist M, Tretyakova NY, Karlsson I. Characterizing Adduct Formation of Electrophilic Skin Allergens with Human Serum Albumin and Hemoglobin. Chem Res Toxicol 2020; 33:2623-2636. [PMID: 32875789 PMCID: PMC7582624 DOI: 10.1021/acs.chemrestox.0c00271] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
![]()
Skin
(contact) allergy, the most predominant form of immunotoxicity
in humans, is caused by small electrophilic compounds (haptens) that
modify endogenous proteins. Approximately 20% of the general population
in the Western world is affected by contact allergy. Although the
importance of the hapten–protein conjugates is well established
in the initiation of the immunological reaction, not much progress
has been made regarding identification of these conjugates in vivo or exploration of their potential as diagnostic
tools. In this study, the human serum albumin (HSA) and human hemoglobin
(Hb) adductome for three representative contact allergens with different
chemical properties, 1-chloro-2,4-dinitrobenzene (DNCB), 1,2-epoxy-3-phenoxypropane
(PGE), and 2-bromo-2-(bromomethyl)glutaronitrile (MDBGN), were studied.
Plasma and red blood cell lysate were used as a source for HSA and
Hb, respectively. The Direct Peptide Reactivity Assay was used to
investigate adduct formation of MDBGN with nucleophilic moieties and
revealed that MDGBN is converted to 2-methylenepentanedinitrile in
the presence of sulfhydryl groups prior to adduct formation. Following
incubation of HSA and Hb with haptens, an Orbitrap Q Exactive high-resolution
mass spectrometer was used to perform an initial untargeted analysis
to screen for adduct formation, followed by confirmation by targeted
Parallel Reaction Monitoring analysis. Although a subset of adducted
sites was confirmed by targeted analysis, only some of the adducted
peptides showed an increase in the relative amount of the adducted
peptide with an increased concentration of hapten. In total, seven
adduct sites for HSA and eight for Hb were confirmed for DNCB and
PGE. These sites are believed to be the most reactive. Further, three
of the HSA sites (Cys34, Cys62, and Lys190) and six of the Hb sites (subunit α: Val1, His45, His72; subunit β: Cys93, His97, and Cys112) were haptenated already
at the lowest level of hapten to protein molar ratio (0.1:1), indicating
that these sites are the most likely to be modified in vivo. To the best of our knowledge, this is the first time that the adductome
of Hb has been studied in the context of contact allergens. Identification
of the most reactive sites of abundant proteins, such as HSA and Hb,
is the first step toward identification of contact allergy biomarkers
that can be used for biomonitoring and to develop better diagnostic
tools based on a blood sample.
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Affiliation(s)
- Lorena Ndreu
- Department of Environmental Science, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Luke N Erber
- Department of Medicinal Chemistry and the College of Pharmacy, University of Minnesota, Minneapolis, Minnesota 55455, United States.,Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Margareta Törnqvist
- Department of Environmental Science, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Natalia Y Tretyakova
- Department of Medicinal Chemistry and the College of Pharmacy, University of Minnesota, Minneapolis, Minnesota 55455, United States.,Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Isabella Karlsson
- Department of Environmental Science, Stockholm University, SE-106 91 Stockholm, Sweden
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Quaranta A, Spasova M, Passarini E, Karlsson I, Ndreu L, Thorsén G, Ilag LL. N-Glycosylation profiling of intact target proteins by high-resolution mass spectrometry (MS) and glycan analysis using ion mobility-MS/MS. Analyst 2020; 145:1737-1748. [DOI: 10.1039/c9an02081k] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Glycosylation characterization could lead to the discovery of biomarkers and is crucial in quality control of biopharmaceuticals. Here we present a method to quantify glycoforms on intact proteins, with parallel glycan identification by IMS-MS/MS.
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Affiliation(s)
- Alessandro Quaranta
- Department of Environmental Science and Analytical Chemistry
- Stockholm University
- 10691 Stockholm
- Sweden
| | - Maya Spasova
- Department of Environmental Science and Analytical Chemistry
- Stockholm University
- 10691 Stockholm
- Sweden
| | - Elena Passarini
- Department of Environmental Science and Analytical Chemistry
- Stockholm University
- 10691 Stockholm
- Sweden
| | - Isabella Karlsson
- Department of Environmental Science and Analytical Chemistry
- Stockholm University
- 10691 Stockholm
- Sweden
| | - Lorena Ndreu
- Department of Environmental Science and Analytical Chemistry
- Stockholm University
- 10691 Stockholm
- Sweden
| | - Gunnar Thorsén
- IVL Swedish Environmental Research Institute
- 11428 Stockholm
- Sweden
| | - Leopold L. Ilag
- Department of Environmental Science and Analytical Chemistry
- Stockholm University
- 10691 Stockholm
- Sweden
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8
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Sroka-Bartnicka A, Karlsson I, Ndreu L, Quaranta A, Pijnappel M, Thorsén G. Particle-based N-linked glycan analysis of selected proteins from biological samples using nonglycosylated binders. J Pharm Biomed Anal 2016; 132:125-132. [PMID: 27718394 DOI: 10.1016/j.jpba.2016.09.029] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Revised: 09/08/2016] [Accepted: 09/24/2016] [Indexed: 12/25/2022]
Abstract
Glycosylation is one of the most common and important post-translational modifications, influencing both the chemical and the biological properties of proteins. Studying the glycosylation of the entire protein population of a sample can be challenging because variations in the concentrations of certain proteins can enhance or obscure changes in glycosylation. Furthermore, alterations in the glycosylation pattern of individual proteins, exhibiting larger variability in disease states, have been suggested as biomarkers for different types of cancer, as well as inflammatory and neurodegenerative diseases. In this paper, we present a rapid and efficient method for glycosylation analysis of individual proteins focusing on changes in the degree of fucosylation or other alterations to the core structure of the glycans, such as the presence of bisecting N-acetylglucosamines and a modified degree of branching. Streptavidin-coated magnetic beads are used in combination with genetically engineered immunoaffinity binders, called VHH antibody fragments. A major advantage of the VHHs is that they are nonglycosylated; thus, enzymatic release of glycans from the targeted protein can be performed directly on the beads. After deglycosylation, the glycans are analyzed by MALDI-TOF-MS. The developed method was evaluated concerning its specificity, and thereafter implemented for studying the glycosylation pattern of two different proteins, alpha-1-antitrypsin and transferrin, in human serum and cerebrospinal fluid. To our knowledge, this is the first example of a protein array-type experiment that employs bead-based immunoaffinity purification in combination with mass spectrometry analysis for fast and efficient glycan analysis of individual proteins in biological fluid.
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Affiliation(s)
- Anna Sroka-Bartnicka
- Department of Environmental Science and Analytical Chemistry, Stockholm University, Stockholm, Sweden
| | - Isabella Karlsson
- Department of Environmental Science and Analytical Chemistry, Stockholm University, Stockholm, Sweden
| | - Lorena Ndreu
- Department of Environmental Science and Analytical Chemistry, Stockholm University, Stockholm, Sweden
| | - Alessandro Quaranta
- Department of Environmental Science and Analytical Chemistry, Stockholm University, Stockholm, Sweden
| | - Matthijs Pijnappel
- Department of Environmental Science and Analytical Chemistry, Stockholm University, Stockholm, Sweden
| | - Gunnar Thorsén
- Department of Environmental Science and Analytical Chemistry, Stockholm University, Stockholm, Sweden.
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