1
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Wagner WJ, Gross ML. Using mass spectrometry-based methods to understand amyloid formation and inhibition of alpha-synuclein and amyloid beta. MASS SPECTROMETRY REVIEWS 2024; 43:782-825. [PMID: 36224716 PMCID: PMC10090239 DOI: 10.1002/mas.21814] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Amyloid fibrils, insoluble β-sheets structures that arise from protein misfolding, are associated with several neurodegenerative disorders. Many small molecules have been investigated to prevent amyloid fibrils from forming; however, there are currently no therapeutics to combat these diseases. Mass spectrometry (MS) is proving to be effective for studying the high order structure (HOS) of aggregating proteins and for determining structural changes accompanying protein-inhibitor interactions. When combined with native MS (nMS), gas-phase ion mobility, protein footprinting, and chemical cross-linking, MS can afford regional and sometimes amino acid spatial resolution of the aggregating protein. The spatial resolution is greater than typical low-resolution spectroscopic, calorimetric, and the traditional ThT fluorescence methods used in amyloid research today. High-resolution approaches can struggle when investigating protein aggregation, as the proteins exist as complex oligomeric mixtures of many sizes and several conformations or polymorphs. Thus, MS is positioned to complement both high- and low-resolution approaches to studying amyloid fibril formation and protein-inhibitor interactions. This review covers basics in MS paired with ion mobility, continuous hydrogen-deuterium exchange (continuous HDX), pulsed hydrogen-deuterium exchange (pulsed HDX), fast photochemical oxidation of proteins (FPOP) and other irreversible labeling methods, and chemical cross-linking. We then review the applications of these approaches to studying amyloid-prone proteins with a focus on amyloid beta and alpha-synuclein. Another focus is the determination of protein-inhibitor interactions. The expectation is that MS will bring new insights to amyloid formation and thereby play an important role to prevent their formation.
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Affiliation(s)
- Wesley J Wagner
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Michael L Gross
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri, USA
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2
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Wagner WJ, Moyle AB, Wagner ND, Rempel DL, Gross ML. Evaluating Chemical Footprinting-Induced Perturbation of Protein Higher Order Structure. Anal Chem 2024; 96:9693-9703. [PMID: 38815160 PMCID: PMC11238718 DOI: 10.1021/acs.analchem.4c01735] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2024]
Abstract
Specific amino acid footprinting mass spectrometry (MS) is an increasingly utilized method for elucidating protein higher order structure (HOS). It does this by adding to certain amino acid residues a mass tag, whose reaction extent depends on solvent accessibility and microenvironment of the protein. Unlike reactive free radicals and carbenes, these specific footprinters react slower than protein unfolding. Thus, their footprinting, under certain conditions, provokes structural changes to the protein, leading to labeling on non-native structures. It is critical to establish conditions (i.e., reagent concentrations, time of reaction) to ensure that the structure of the protein following footprinting remains native. Here, we compare the efficacy of five methods in assessing protein HOS following footprinting at the intact protein level and then further localize the perturbation at the peptide level. Three are MS-based methods that provide dose-response plot analysis, evaluation of Poisson distributions of precursor and products, and determination of the average number of modifications. These MS-based methods reliably and effectively indicate HOS perturbation at the intact protein level, whereas spectroscopic methods (circular dichroism (CD) and dynamic light scattering (DLS)) are less sensitive in monitoring subtle HOS perturbation caused by footprinting. Evaluation of HOS at the peptide level indicates regions that are sensitive to localized perturbations. Peptide-level analysis also provides higher resolution of the HOS perturbation, and we recommend using it for future footprinting studies. Overall, this work shows conclusive evidence for HOS perturbation caused by footprinting. Implementation of quality control workflows can identify conditions to avoid the perturbation, for footprinting, allowing accurate and reliable identification of protein structural changes that accompany, for example, ligand interactions, mutations, and changes in solution environment.
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Affiliation(s)
- Wesley J Wagner
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri 63130 United States
| | - Austin B Moyle
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri 63130 United States
| | - Nicole D Wagner
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri 63130 United States
| | - Don L Rempel
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri 63130 United States
| | - Michael L Gross
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri 63130 United States
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3
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Kirsch ZJ, Vachet RW. Proteins Can Withstand More Extensive Labeling while Providing Accurate Structural Information in Covalent Labeling-Mass Spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2024; 35:1030-1039. [PMID: 38581471 PMCID: PMC11167616 DOI: 10.1021/jasms.4c00043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/08/2024]
Abstract
Diethylpyrocarbonate (DEPC) covalent labeling-mass spectrometry (CL-MS) has been extensively utilized to study protein structure and interactions owing to its ease of use, commercial availability, and broad labeling of nucleophilic residues. During typical CL-MS experiments with DEPC, the extent of labeling is kept low to avoid any structural perturbations resulting from covalent modification of the protein. In this study, we demonstrate that proteins can be labeled more extensively via DEPC and still provide accurate structural information. To show this, we modeled labeling kinetics over a range of DEPC concentrations and used molecular dynamics simulations to investigate the molecular-level effects of extensive labeling on the protein structure. Our results indicate that higher extents of DEPC labeling do not significantly perturb the protein structure and can lead to improved precision, detectability of labeled peptides, and protein structural resolution. Furthermore, higher extents of labeling enable better identification of protein-ligand binding sites where lower extents of modification provide ambiguous results.
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Affiliation(s)
- Zachary J. Kirsch
- Department of Chemistry, University of Massachusetts Amherst, Amherst, Massachusetts 01003, United States
| | - Richard W. Vachet
- Department of Chemistry, University of Massachusetts Amherst, Amherst, Massachusetts 01003, United States
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4
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Dhingra K, Sinha I, Snyder M, Roush D, Cramer SM. Exploring preferred binding domains of IgG1 mAbs to multimodal adsorbents using a combined biophysics and simulation approach. Biotechnol Prog 2024; 40:e3415. [PMID: 38043031 DOI: 10.1002/btpr.3415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Revised: 10/19/2023] [Accepted: 11/13/2023] [Indexed: 12/04/2023]
Abstract
In this work, we employ a recently developed biophysical technique that uses diethylpyrocarbonate (DEPC) covalent labeling and mass spectrometry for the identification of mAb binding patches to two multimodal cation exchange resins at different pH. This approach compares the labeling results obtained in the bound and unbound states to identify residues that are sterically shielded and thus located in the mAb binding domains. The results at pH 6 for one mAb (mAb B) indicated that while the complementarity determining region (CDR) had minimal interactions with both resins, the FC domain was actively involved in binding. In contrast, DEPC/MS data with another mAb (mAb C) indicated that both the CDR and FC domains were actively involved in binding. These results corroborated chromatographic retention data with these two mAbs and their fragments and helped to explain the significantly stronger retention of both the intact mAb C and its Fab fragment. In contrast, labeling results with mAb C at pH 7, indicated that only the CDR played a significant role in resin binding, again corroborating chromatographic data. The binding domains identified from the DEPC/MS experiments were also examined using protein surface hydrophobicity maps obtained using a recently developed sparse sampling molecular dynamics (MD) approach in concert with electrostatic potential maps. These results demonstrate that the DEPC covalent labeling/mass spectrometry technique can provide important information about the domain contributions of multidomain proteins such as monoclonal antibodies when interacting with multimodal resins over a range of pH conditions.
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Affiliation(s)
- Kabir Dhingra
- Howard P. Isermann Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, New York, USA
- Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York, USA
| | - Imee Sinha
- Howard P. Isermann Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, New York, USA
- Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York, USA
| | - Mark Snyder
- Process Chemistry Division, Bio-Rad Laboratories, Hercules, California, USA
| | - David Roush
- Process R&D, Merck &Co., Inc., Rahway, New Jersey, USA
| | - Steven M Cramer
- Howard P. Isermann Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, New York, USA
- Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York, USA
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5
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Moyle AB, Wagner ND, Wagner WJ, Cheng M, Gross ML. Workflow for Validating Specific Amino Acid Footprinting Reagents for Protein Higher Order Structure Elucidation. Anal Chem 2023; 95:10119-10126. [PMID: 37351860 PMCID: PMC10476636 DOI: 10.1021/acs.analchem.3c01919] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/24/2023]
Abstract
Protein footprinting mass spectrometry probes protein higher order structure and dynamics by labeling amino acid side-chains or backbone amides as a function of solvent accessibility. One category of footprinting uses residue-specific, irreversible covalent modifications, affording flexibility of sample processing for bottom-up analysis. Although several specific amino acid footprinting technologies are becoming established in structural proteomics, there remains a need to assess fundamental properties of new reagents before their application. Often, footprinting reagents are applied to complex or novel protein systems soon after their discovery and sometimes without a thorough investigation of potential downsides of the reagent. In this work, we assemble and test a validation workflow that utilizes cyclic peptides and a model protein to characterize benzoyl fluoride, a recently published, next-generation nucleophile footprinter. The workflow includes the characterization of potential side-chain reactive groups, reaction "quench" efficacies, reagent considerations and caveats (e.g., buffer pH), residue-specific kinetics compared to those of established reagents, and protein-wide characterization of modification sites with considerations for proteolysis. The proposed workflow serves as a starting point for improved footprinting reagent discovery, validation, and introduction, the aspects of which we recommend before applying to unknown protein systems.
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Affiliation(s)
- Austin B. Moyle
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130 United States
| | - Nicole D. Wagner
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130 United States
| | - Wesley J. Wagner
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130 United States
| | - Ming Cheng
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130 United States
| | - Michael L. Gross
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130 United States
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6
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Xu X, Huang L, Wu Y, Li Z, Huang L. A novel nanostructured organic framework sensor for selective and sensitive detection of doxycycline based on fluorescence enhancement. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2023; 288:122143. [PMID: 36459722 DOI: 10.1016/j.saa.2022.122143] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 11/05/2022] [Accepted: 11/20/2022] [Indexed: 06/17/2023]
Abstract
It is critical for human health to develop sensitive and rapid analytical methods for detecting doxycycline (DOX) residues in food. This paper presents a novel metal-organic framework nanomaterial (Zn-MOF) based on dithiodiglycolic acid and its application in DOX detection by fluorescent probe method. Zn-MOF itself does not fluoresce. When DOX is added, the system exhibits strong fluorescence (100-fold) at 530 nm. The fluorescence intensity displayed an excellent linear relationship with DOX concentration with a detection limit of 2.7 nM. The reaction solution's fluorescence displayed a visible color shift from colorless to yellow that was concentration-dependent. A smartphone was used to detect DOX by recognizing the red, green, and blue values of the reaction solution and the corresponding test paper. The use of smartphones can speed up the detection process and streamline operations, offering a sensitive and visible method for the quantitative detection of DOX residues in actual samples. Interestingly, Zn-MOF can discriminate DOX from other tetracyclines with high selectivity. This material has been used successfully as a fluorescent probe to determine DOX in fish samples with an average spiked recovery of 94.6 % ∼ 95.1 %. The DOX levels in the measured perch samples were 1.25 ∼ 157 μg/kg. There are 2 batches of DOX exceeding the standard in 14 batches.
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Affiliation(s)
- Xiaowen Xu
- School of Pharmacy, Fujian Medical University, Fuzhou, Fujian 350122, China
| | - Lingyi Huang
- School of Pharmacy, Fujian Medical University, Fuzhou, Fujian 350122, China
| | - Youjia Wu
- School of Pharmacy, Fujian Medical University, Fuzhou, Fujian 350122, China
| | - Zhenyue Li
- School of Pharmacy, Fujian Medical University, Fuzhou, Fujian 350122, China
| | - Liying Huang
- School of Pharmacy, Fujian Medical University, Fuzhou, Fujian 350122, China.
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7
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Dhingra K, Gudhka RB, Cramer SM. Evaluation of preferred binding regions on ubiquitin and IgG1 F C for interacting with multimodal cation exchange resins using DEPC labeling/mass spectrometry. Biotechnol Bioeng 2023; 120:1592-1604. [PMID: 36814367 DOI: 10.1002/bit.28361] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 02/06/2023] [Accepted: 02/14/2023] [Indexed: 02/24/2023]
Abstract
There is significant interest in identifying the preferred binding domains of biological products to various chromatographic materials. In this work, we develop a biophysical technique that uses diethyl pyrocarbonate (DEPC) based covalent labeling in concert with enzymatic digestion and mass spectrometry to identify the binding patches for proteins bound to commercially available multimodal (MM) cation exchange chromatography resins. The technique compares the changes in covalent labeling of the protein in solution and in the bound state and uses the differences in this labeling to identify residues that are sterically shielded upon resin binding and, therefore, potentially involved in the resin binding process. Importantly, this approach enables the labeling of many amino acids and can be carried out over a pH range of 5.5-7.5, thus enabling the protein surface mapping at conditions of interest in MM cation exchange systems. The protocol is first developed using the model protein ubiquitin and the results indicate that lysine residues located on the front face of the protein show dramatic changes in DEPC labeling while residues present on other regions have minimal or no reductions. This indicates that the front face of ubiquitin is likely involved in resin binding. In addition, surface property maps indicate that the hypothesized front face binding region consists of overlapping positively charged and hydrophobic patches. The technique is then employed with an IgG1 FC and the results indicate that residues on the CH 2-CH 3 interface and the hinge are significantly sterically shielded upon binding to the resin. Further, these regions are again associated with significant overlap of positively charged and hydrophobic patches. On the other hand, while, residues on the CH 2 and the front face of the IgG1 FC also exhibited some changes in DEPC labeling upon binding, these regions have less distinct charged and hydrophobic patches. Importantly, the hypothesized binding patches identified for both ubiquitin and FC using this approach are shown to be consistent with previously reported NMR studies. In contrast to NMR, this new approach enables the identification of preferred binding regions without the need for isotopically labeled proteins or chemical shift assignments. The technique developed in this work sets the stage for the evaluation of the binding domains of a wide range of biological products to chromatographic surfaces, with important implications for designing biomolecules with improved biomanufacturability properties.
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Affiliation(s)
- Kabir Dhingra
- Howard P. Isermann Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, New York, USA.,Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York, USA
| | - Ronak B Gudhka
- Process Development, Drug Substance Biologics, Amgen, Cambridge, Massachusetts, USA
| | - Steven M Cramer
- Howard P. Isermann Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, New York, USA.,Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York, USA
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8
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Pan X, Tran T, Kirsch ZJ, Thompson LK, Vachet RW. Diethylpyrocarbonate-Based Covalent Labeling Mass Spectrometry of Protein Interactions in a Membrane Complex System. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2023; 34:82-91. [PMID: 36475668 PMCID: PMC9812933 DOI: 10.1021/jasms.2c00262] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Membrane-associated proteins are important because they mediate interactions between a cell's external and internal environment and they are often targets of therapeutics. Characterizing their structures and binding interactions, however, is challenging because they typically must be solubilized using artificial membrane systems that can make measurements difficult. Mass spectrometry (MS) is emerging as a valuable tool for studying membrane-associated proteins, and covalent labeling MS has unique potential to provide higher order structure and binding information for these proteins in complicated membrane systems. Here, we demonstrate that diethylpyrocarbonate (DEPC) can be effectively used as a labeling reagent to characterize the binding interactions between a membrane-associated protein and its binding partners in an artificial membrane system. Using chemotaxis histidine kinase (CheA) as a model system, we demonstrate that DEPC-based covalent labeling MS can provide structural and binding information about the ternary complex of CheA with two other proteins that is consistent with structural models of this membrane-associated chemoreceptor system. Despite the moderate hydrophobicity of DEPC, we find that its reactivity with proteins is not substantially influenced by the presence of the artificial membranes. However, correct structural information for this multiprotein chemoreceptor system requires measurements of DEPC labeling at multiple reagent concentrations to enable an accurate comparison between CheA and its ternary complex in the chemoreceptor system. In addition to providing structural information that is consistent with the model of this complex system, the labeling data supplements structural information that is not sufficiently refined in the chemoreceptor model.
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Affiliation(s)
- Xiao Pan
- Department of Chemistry, University of Massachusetts Amherst, Amherst, MA 01003
| | - Thomas Tran
- Molecular and Cellular Biology Program, University of Massachusetts Amherst, Amherst, MA 01003
| | - Zachary J. Kirsch
- Department of Chemistry, University of Massachusetts Amherst, Amherst, MA 01003
| | - Lynmarie K. Thompson
- Department of Chemistry, University of Massachusetts Amherst, Amherst, MA 01003
- Molecular and Cellular Biology Program, University of Massachusetts Amherst, Amherst, MA 01003
| | - Richard W. Vachet
- Department of Chemistry, University of Massachusetts Amherst, Amherst, MA 01003
- Molecular and Cellular Biology Program, University of Massachusetts Amherst, Amherst, MA 01003
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9
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Stein A, Hilken née Thomopoulou P, Frias C, Hopff SM, Varela P, Wilke N, Mariappan A, Neudörfl JM, Fedorov AY, Gopalakrishnan J, Gigant B, Prokop A, Schmalz HG. B-nor-methylene Colchicinoid PT-100 Selectively Induces Apoptosis in Multidrug-Resistant Human Cancer Cells via an Intrinsic Pathway in a Caspase-Independent Manner. ACS OMEGA 2022; 7:2591-2603. [PMID: 35097257 PMCID: PMC8792921 DOI: 10.1021/acsomega.1c04659] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Accepted: 12/31/2021] [Indexed: 05/14/2023]
Abstract
Colchicine, the main active alkaloid from Colchicum autumnale L., is a potent tubulin binder and represents an interesting lead structure for the development of potential anticancer chemotherapeutics. We report on the synthesis and investigation of potentially reactive colchicinoids and their surprising biological activities. In particular, the previously undescribed colchicinoid PT-100, a B-ring contracted 6-exo-methylene colchicinoid, exhibits extraordinarily high antiproliferative and apoptosis-inducing effects on various types of cancer cell lines like acute lymphoblastic leukemia (Nalm6), acute myeloid leukemia (HL-60), Burkitt-like lymphoma (BJAB), human melanoma (MelHO), and human breast adenocarcinoma (MCF7) cells at low nanomolar concentrations. Apoptosis induction proved to be especially high in multidrug-resistant Nalm6-derived cancer cell lines, while healthy human leukocytes and hepatocytes were not affected by the concentration range studied. Furthermore, caspase-independent initiation of apoptosis via an intrinsic pathway was observed. PT-100 also shows strong synergistic effects in combination with vincristine on BJAB and Nalm6 cells. Cocrystallization of PT-100 with tubulin dimers revealed its (noncovalent) binding to the colchicine-binding site of β-tubulin at the interface to the α-subunit. A pronounced effect of PT-100 on the cytoskeleton morphology was shown by fluorescence microscopy. While the reactivity of PT-100 as a weak Michael acceptor toward thiols was chemically proven, it remains unclear whether this contributes to the remarkable biological properties of this unusual colchicinoid.
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Affiliation(s)
- Andreas Stein
- Department
of Chemistry, University of Cologne, 50939 Cologne, Germany
| | | | - Corazon Frias
- Department
of Paediatric Oncology, Children’s
Hospital Cologne, 50735 Cologne, Germany
| | - Sina M. Hopff
- Department
of Paediatric Oncology, Children’s
Hospital Cologne, 50735 Cologne, Germany
| | - Paloma Varela
- Université
Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the
Cell (I2BC), 91198 Gif-sur-Yvette cedex, France
| | - Nicola Wilke
- Department
of Paediatric Oncology, Children’s
Hospital Cologne, 50735 Cologne, Germany
| | - Arul Mariappan
- Laboratory
for Centrosome and Cytoskeleton Biology, Institute of Human Genetics, Heinrich-Heine-University, 40225 Düsseldorf, Germany
| | | | - Alexey Yu Fedorov
- Department
of Organic Chemistry, N.I. Lobachevsky State
University of Nizhny Novgorod, 603950 Nizhny Novgorod, Russian
Federation
| | - Jay Gopalakrishnan
- Laboratory
for Centrosome and Cytoskeleton Biology, Institute of Human Genetics, Heinrich-Heine-University, 40225 Düsseldorf, Germany
| | - Benoît Gigant
- Université
Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the
Cell (I2BC), 91198 Gif-sur-Yvette cedex, France
| | - Aram Prokop
- Department
of Paediatric Oncology, Children’s
Hospital Cologne, 50735 Cologne, Germany
- Department
of Pediatric Hematology/Oncology, Helios
Clinic Schwerin, 19055 Schwerin, Germany
- MSH
Medical School Hamburg, Am Kaiserkai 1, 20457 Hamburg, Germany
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10
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Pan X, Kirsch ZJ, Vachet RW. Distinguishing Histidine Tautomers in Proteins Using Covalent Labeling-Mass Spectrometry. Anal Chem 2022; 94:1003-1010. [PMID: 34962759 PMCID: PMC8787799 DOI: 10.1021/acs.analchem.1c03902] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
In this work, we use diethylpyrocarbonate (DEPC)-based covalent labeling together with LC-MS/MS analysis to distinguish the two sidechain tautomers of histidine residues in peptides and proteins. From labeling experiments on model peptides, we demonstrate that DEPC reacts equally with both tautomeric forms to produce chemically different products with distinct dissociation patterns and LC retention times, allowing the ratios of the two tautomers to be determined in peptides and proteins. Upon measuring the tautomer ratios of several histidine residues in myoglobin, we find good agreement with previous 2D NMR data on this protein. Because our DEPC labeling/MS approach is simpler, faster, and more precise than 2D NMR, our method will be a valuable way to determine how protein structure enforces histidine sidechain tautomerization. Because the tautomeric state of histidine residues is often important for protein structure and function, the ability of DEPC labeling/MS to distinguish histidine tautomers should equip researchers with a tool to understand the histidine residue structure and function more deeply in proteins.
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11
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Tremblay CY, Kirsch ZJ, Vachet RW. Epitope Mapping with Diethylpyrocarbonate Covalent Labeling-Mass Spectrometry. Anal Chem 2022; 94:1052-1059. [PMID: 34932327 PMCID: PMC8785103 DOI: 10.1021/acs.analchem.1c04038] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Antigen-antibody epitope mapping is essential for understanding binding mechanisms and developing new protein therapeutics. In this study, we investigate diethylpyrocarbonate (DEPC) covalent labeling-mass spectrometry as a means of analyzing antigen-antibody interactions using the well-characterized model system of TNFα in complex with three different antibodies. Results show that residues buried in the epitope undergo substantial decreases in labeling, as expected. Interestingly, serine, threonine, and tyrosine residues at the edges of the epitope undergo unexpected increases in labeling. The increased labeling of these weakly nucleophilic residues is caused by the formation of hydrophobic pockets upon antibody binding that presumably increase local DEPC concentrations. Residues that are distant from the epitope generally do not undergo changes in labeling extent; however, some that do change experience variations in their local microenvironment due to side-chain reorganization or stabilization of the TNFα trimer that occurs upon binding. Overall, DEPC labeling of antigen-antibody complexes is found to depend on both changes in solvent exposure and changes to the residue microenvironment.
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12
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Tremblay CY, Limpikirati P, Vachet RW. Complementary Structural Information for Stressed Antibodies from Hydrogen-Deuterium Exchange and Covalent Labeling Mass Spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2021; 32:1237-1248. [PMID: 33886284 PMCID: PMC8177069 DOI: 10.1021/jasms.1c00072] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Identifying changes in the higher-order structure (HOS) of therapeutic monoclonal antibodies upon storage, stress, or mishandling is important for ensuring efficacy and avoiding adverse effects. Here, we demonstrate diethylpyrocarbonate (DEPC)-based covalent labeling (CL) mass spectrometry (MS) and hydrogen-deuterium exchange (HDX)/MS can be used together to provide site-specific information about subtle conformational changes that are undetectable by traditional techniques. Using heat-stressed rituximab as a model protein, we demonstrate that CL/MS is more sensitive than HDX/MS to subtle HOS structural changes under low stress conditions (e.g., 45 and 55 °C for 4 h). At higher heat stress (65 °C for 4 h), we find CL/MS and HDX/MS provide complementary information, as CL/MS reports on changes in side chain orientation while HDX/MS reveals changes in backbone dynamics. More interestingly, we demonstrate that the two techniques work synergistically to identify likely aggregation sites in the heat-stressed protein. In particular, the CH3 and CL domains experience decreases in deuterium uptake after heat stress, while only the CH3 domain experiences decreases in DEPC labeling extent as well, suggesting the CH3 domain is a likely site of aggregation and the CL domain only undergoes a decrease in backbone dynamics. The combination of DEPC-CL/MS and HDX/MS provides valuable structural information, and the two techniques should be employed together when investigating the HOS of protein therapeutics.
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Affiliation(s)
- Catherine Y. Tremblay
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | - Patanachai Limpikirati
- Current Address: Department of Food and Pharmaceutical Chemistry, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok 10330, Thailand
| | - Richard W. Vachet
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, United States
- To whom correspondence should be addressed:
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13
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Liu XR, Rempel DL, Gross ML. Protein higher-order-structure determination by fast photochemical oxidation of proteins and mass spectrometry analysis. Nat Protoc 2020; 15:3942-3970. [PMID: 33169002 PMCID: PMC10476649 DOI: 10.1038/s41596-020-0396-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 08/03/2020] [Indexed: 11/09/2022]
Abstract
The higher-order structure (HOS) of proteins plays a critical role in their function; therefore, it is important to our understanding of their function that we have as much information as possible about their three-dimensional structure and how it changes with time. Mass spectrometry (MS) has become an important tool for determining protein HOS owing to its high throughput, mid-to-high spatial resolution, low sample amount requirement and broad compatibility with various protein systems. Modern MS-based protein HOS analysis relies, in part, on footprinting, where a reagent reacts 'to mark' the solvent-accessible surface of the protein, and MS-enabled proteomic analysis locates the modifications to afford a footprint. Fast photochemical oxidation of proteins (FPOP), first introduced in 2005, has become a powerful approach for protein footprinting. Laser-induced hydrogen peroxide photolysis generates hydroxyl radicals that react with solvent-accessible side chains (14 out of 20 amino acid side chains) to fulfill the footprinting. The reaction takes place at sub-milliseconds, faster than most of labeling-induced protein conformational changes, thus enabling a 'snapshot' of protein HOS in solution. As a result, FPOP has been employed in solving several important problems, including mapping epitopes, following protein aggregation, locating small molecule binding, measuring ligand-binding affinity, monitoring protein folding and unfolding and determining hidden conformational changes invisible to other methods. Broader adoption will be promoted by dissemination of the technical details for assembling the FPOP platform and for dealing with the complexities of analyzing FPOP data. In this protocol, we describe the FPOP platform, the conditions for successful footprinting and its examination by mass measurements of the intact protein, the post-labeling sample handling and digestion, the liquid chromatography-tandem MS analysis of the digested sample and the data analysis with Protein Metrics Suite. This protocol is intended not only as a guide for investigators trying to establish an FPOP platform in their own lab but also for those willing to incorporate FPOP as an additional tool in addressing their questions of interest.
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Affiliation(s)
- Xiaoran Roger Liu
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO, USA.
| | - Don L Rempel
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO, USA
| | - Michael L Gross
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO, USA.
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14
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Liu T, Marcinko TM, Vachet RW. Protein-Ligand Affinity Determinations Using Covalent Labeling-Mass Spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2020; 31:1544-1553. [PMID: 32501685 PMCID: PMC7332385 DOI: 10.1021/jasms.0c00131] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Determining the binding affinity is an important aspect of characterizing protein-ligand complexes. Here, we describe an approach based on covalent labeling (CL)-mass spectrometry (MS) that can accurately provide protein-ligand dissociation constants (Kd values) using diethylpyrocarbonate (DEPC) as the labeling reagent. Even though DEPC labeling reactions occur on a time scale that is similar to the dissociation/reassociation rates of many protein-ligand complexes, we demonstrate that relatively accurate binding constants can still be obtained as long as the extent of protein labeling is kept below 30%. Using two well-established model systems and one insufficiently characterized system, we find that Kd values can be determined that are close to values obtained in previous measurements. The CL-MS-based strategy that is described here should serve as an alternative for characterizing protein-ligand complexes that are challenging to measure by other methods. Moreover, this method has the potential to provide, simultaneously, the affinity and binding site information.
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Affiliation(s)
| | | | - Richard W. Vachet
- Corresponding author: Prof. Richard W. Vachet, Department of Chemistry, University of Massachusetts, Amherst, MA 01003, , Phone: (413) 545-2733
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15
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Limpikirati PK, Zhao B, Pan X, Eyles SJ, Vachet RW. Covalent Labeling/Mass Spectrometry of Monoclonal Antibodies with Diethylpyrocarbonate: Reaction Kinetics for Ensuring Protein Structural Integrity. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2020; 31:1223-1232. [PMID: 32310649 PMCID: PMC7370534 DOI: 10.1021/jasms.0c00067] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Diethylpyrocarbonate (DEPC)-based covalent labeling together with mass spectrometry is a promising tool for the higher-order structural analysis of antibody therapeutics. Reliable information about antibody higher-order structure can be obtained, though, only when the protein's structural integrity is preserved during labeling. In this work, we have evaluated the applicability of DEPC reaction kinetics for ensuring the structural integrity of monoclonal antibodies (mAbs) during labeling. By monitoring the modification extent of selected proteolytic fragments as a function of DEPC concentration, we find that a common DEPC concentration can be used for different monoclonal antibodies in formulated samples without perturbing their higher-order structure. Under these labeling conditions, we find that the antibodies can accommodate up to four DEPC modifications without being structurally perturbed, indicating that multidomain proteins can withstand more than one label, which contrasts to previously studied single-domain proteins. This more extensive labeling provides a more sensitive measure of structure, making DEPC-based covalent labeling-mass spectrometry suitable for the higher-order structural analyses of mAbs.
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Affiliation(s)
- Patanachai K. Limpikirati
- Department of Chemistry, University of Massachusetts Amherst, Amherst, Massachusetts 01003, United States
| | - Bo Zhao
- Department of Chemistry, University of Massachusetts Amherst, Amherst, Massachusetts 01003, United States
| | - Xiao Pan
- Department of Chemistry, University of Massachusetts Amherst, Amherst, Massachusetts 01003, United States
| | - Stephen J. Eyles
- Department of Biochemistry and Molecular Biology, University of Massachusetts Amherst, Amherst, Massachusetts 01003, United States
| | - Richard W. Vachet
- Department of Chemistry, University of Massachusetts Amherst, Amherst, Massachusetts 01003, United States
- Corresponding author, Phone: (413) 545-2733 (R.W.V.)
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16
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Liu XR, Zhang MM, Gross ML. Mass Spectrometry-Based Protein Footprinting for Higher-Order Structure Analysis: Fundamentals and Applications. Chem Rev 2020; 120:4355-4454. [PMID: 32319757 PMCID: PMC7531764 DOI: 10.1021/acs.chemrev.9b00815] [Citation(s) in RCA: 130] [Impact Index Per Article: 32.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Proteins adopt different higher-order structures (HOS) to enable their unique biological functions. Understanding the complexities of protein higher-order structures and dynamics requires integrated approaches, where mass spectrometry (MS) is now positioned to play a key role. One of those approaches is protein footprinting. Although the initial demonstration of footprinting was for the HOS determination of protein/nucleic acid binding, the concept was later adapted to MS-based protein HOS analysis, through which different covalent labeling approaches "mark" the solvent accessible surface area (SASA) of proteins to reflect protein HOS. Hydrogen-deuterium exchange (HDX), where deuterium in D2O replaces hydrogen of the backbone amides, is the most common example of footprinting. Its advantage is that the footprint reflects SASA and hydrogen bonding, whereas one drawback is the labeling is reversible. Another example of footprinting is slow irreversible labeling of functional groups on amino acid side chains by targeted reagents with high specificity, probing structural changes at selected sites. A third footprinting approach is by reactions with fast, irreversible labeling species that are highly reactive and footprint broadly several amino acid residue side chains on the time scale of submilliseconds. All of these covalent labeling approaches combine to constitute a problem-solving toolbox that enables mass spectrometry as a valuable tool for HOS elucidation. As there has been a growing need for MS-based protein footprinting in both academia and industry owing to its high throughput capability, prompt availability, and high spatial resolution, we present a summary of the history, descriptions, principles, mechanisms, and applications of these covalent labeling approaches. Moreover, their applications are highlighted according to the biological questions they can answer. This review is intended as a tutorial for MS-based protein HOS elucidation and as a reference for investigators seeking a MS-based tool to address structural questions in protein science.
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Affiliation(s)
| | | | - Michael L. Gross
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO, USA, 63130
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17
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Cheng M, Asuru A, Kiselar J, Mathai G, Chance MR, Gross ML. Fast Protein Footprinting by X-ray Mediated Radical Trifluoromethylation. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2020; 31:1019-1024. [PMID: 32255631 PMCID: PMC7486011 DOI: 10.1021/jasms.0c00085] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Synchrotron radiolysis generates hydroxyl radicals (•OH) that are successful footprinting reagents. Here, we describe a new reagent for the synchrotron platform, the trifluoromethyl radical (•CF3). The radical is produced by •OH displacement of •CF3 from sodium triflinate (Langlois reagent). Upon X-ray beam exposure, the reagent labels proteins extensively without any additional chemicals on a millisecond or shorter time scale. The •CF3 is comparably reactive to •OH and produces footprinting information that complements that of •OH alone. This reagent in combination with •OH should enable novel chemistry for protein footprinting on the synchrotron platform.
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Affiliation(s)
- Ming Cheng
- Department of Chemistry, Washington University, St. Louis, Missouri 63130, United States
| | - Awuri Asuru
- Center for Proteomics & Bioinformatics, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, United States
| | - Janna Kiselar
- Center for Proteomics & Bioinformatics, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, United States
| | - George Mathai
- Department of Chemistry, Sacred Heart College, Thevara, Kochi, Kerala 682013, India
| | - Mark R. Chance
- Center for Proteomics & Bioinformatics, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, United States
- Corresponding Authors: MLG: Tel: (314)935-4814. Fax: (314)935-7484. , MRC: Phone: (216) 368-4406. Fax: (216) 368-3812.
| | - Michael L. Gross
- Department of Chemistry, Washington University, St. Louis, Missouri 63130, United States
- Corresponding Authors: MLG: Tel: (314)935-4814. Fax: (314)935-7484. , MRC: Phone: (216) 368-4406. Fax: (216) 368-3812.
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18
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Zhao B, Zhuang J, Xu M, Liu T, Limpikirati P, Thayumanavan S, Vachet RW. Covalent Labeling with an α,β-Unsaturated Carbonyl Scaffold for Studying Protein Structure and Interactions by Mass Spectrometry. Anal Chem 2020; 92:6637-6644. [PMID: 32250591 PMCID: PMC7207043 DOI: 10.1021/acs.analchem.0c00463] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A new covalent labeling (CL) reagent based on an α,β-unsaturated carbonyl scaffold has been developed for studying protein structure and protein-protein interactions when coupled with mass spectrometry. We show that this new reagent scaffold can react with up to 13 different types of residues on protein surfaces, thereby providing excellent structural resolution. To illustrate the value of this reagent scaffold, it is used to identify the residues involved in the protein-protein interface that is formed upon Zn(II) binding to the protein β-2-microglobulin. The modular design of the α,β-unsaturated carbonyl scaffold allows facile variation of the functional groups, enabling labeling kinetics and selectivity to be tuned. Moreover, by introducing isotopically enriched functional groups into the reagent structure, labeling sites can be more easily identified by MS and MS/MS. Overall, this reagent scaffold should be a valuable CL reagent for protein higher order structure characterization by MS.
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Affiliation(s)
- Bo Zhao
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, USA
| | - Jiaming Zhuang
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, USA
| | - Miaowei Xu
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, USA
| | - Tianying Liu
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, USA
| | | | - S. Thayumanavan
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, USA
- Molecular and Cellular Biology Program, University of Massachusetts, Amherst, Massachusetts 01003, USA
- Center for Bioactive Delivery – Institute for Applied Life Sciences, University of Massachusetts, Amherst, Massachusetts 01003, USA
| | - Richard W. Vachet
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, USA
- Molecular and Cellular Biology Program, University of Massachusetts, Amherst, Massachusetts 01003, USA
- Center for Bioactive Delivery – Institute for Applied Life Sciences, University of Massachusetts, Amherst, Massachusetts 01003, USA
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19
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Evaluation of NHS-Acetate and DEPC labelling for determination of solvent accessible amino acid residues in protein complexes. J Proteomics 2020; 222:103793. [PMID: 32348883 DOI: 10.1016/j.jprot.2020.103793] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 02/27/2020] [Accepted: 04/19/2020] [Indexed: 02/07/2023]
Abstract
The activity of most proteins and protein complexes relies on the formation of defined three-dimensional structures. The analysis of these arrangements is therefore key for understanding their function and regulation in the cell. Besides the traditional structural techniques, structural mass spectrometry delivers insights into the various aspects of protein structure, including stoichiometry, protein-ligand interactions and solvent accessibility. The latter is usually obtained from labelling experiments. In this study, we evaluate two chemical labelling strategies using N-hydroxysuccinimidyl acetate and diethylpyrocarbonate as labelling reagents. We characterised the mass spectra of modified peptides and assessed labelling reactivity of individual amino acid residues in intact proteins. Importantly, we uncovered neutral losses from diethylpyrocarbonate modified amino acids improving the assignments of the peptide fragment spectra. We further established a quantitative labelling workflow to determine labelling percentage and unambiguously distinguish solvent accessible amino acid residues from stochastically labelled residues. Finally, we used ion mobility MS to explore whether labelled proteins maintain their structures and remain stable. We conclude that labelling using N-hydroxysuccinimidyl acetate and diethylpyrocarbonate delivers comparable results, however, N-hydroxysuccinimidyl acetate labelling is compatible with standard proteomic workflows while diethylpyrocarbonate labelling requires specialised experimental conditions and data analysis. SIGNIFICANCE: Covalent labelling is widely used to identify solvent accessible amino acid residues of proteins or protein complexes. However, with increasing sensitivity of available MS instrumentation, a high number of modified residues is usually observed making an unambiguous assignment of solvent accessible residues necessary. In this study, we establish a quantitative labelling workflow for two different labelling strategies to identify accessible amino acid residues. In addition, we characterise observed mass spectra of modified peptides and identified neutral loss of DEPC modified amino acid residues during HCD fragmentation improving their assignments.
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20
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Pan X, Limpikirati P, Chen H, Liu T, Vachet RW. Higher-Order Structure Influences the Kinetics of Diethylpyrocarbonate Covalent Labeling of Proteins. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2020; 31:658-665. [PMID: 32013423 PMCID: PMC7077735 DOI: 10.1021/jasms.9b00132] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The combination of covalent labeling (CL) and mass spectrometry (MS) has emerged as a useful tool for studying protein structure due to its good structural coverage, the ability to study proteins in mixtures, and its high sensitivity. Diethylpyrocarbonate (DEPC) is an effective CL reagent that can label N-termini and the side chains of several nucleophilic residues, providing information for about 30% of the residues in the average protein. For DEPC to provide accurate structural information, the extent of labeling must be controlled to minimize label-induced structural perturbations. In this work, we establish a quantitative correlation between general protein structural factors and DEPC reaction rates by measuring the reaction rate coefficients for several model proteins. Using principal component and regression analyses, we find that the solvent accessible surface areas of histidine and lysine residues in proteins are the primary factors that determine a protein's reactivity toward DEPC, despite the fact that other more abundant residues, such as tyrosine, threonine, and serine, are also labeled by DEPC. From the statistical analysis, a model emerges that can be used to predict the reactivity of a protein based on its structure and sequence, allowing the optimal DEPC concentration to be chosen for a given protein. The resulting model is supported by cross-validation studies and by accurately predicting of the reactivity of five test proteins. Overall, our model reveals interesting insight into the reactivity of proteins with DEPC, and it will facilitate identification of optimal DEPC labeling conditions for proteins.
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Affiliation(s)
- Xiao Pan
- Department of Chemistry, University of Massachusetts Amherst, Amherst, MA 01003, United States
| | - Patanachai Limpikirati
- Department of Chemistry, University of Massachusetts Amherst, Amherst, MA 01003, United States
| | - Huan Chen
- Department of Mathematical Sciences, School of Natural Sciences and Mathematics, University of Texas at Dallas, Richardson, TX 75080, United States
| | - Tianying Liu
- Department of Chemistry, University of Massachusetts Amherst, Amherst, MA 01003, United States
| | - Richard W. Vachet
- Department of Chemistry, University of Massachusetts Amherst, Amherst, MA 01003, United States
- Corresponding Author:; Phone: (413) 545-2733 (R.W.V.)
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21
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Marcinko TM, Drews T, Liu T, Vachet RW. Epigallocatechin-3-gallate Inhibits Cu(II)-Induced β-2-Microglobulin Amyloid Formation by Binding to the Edge of Its β-Sheets. Biochemistry 2020; 59:1093-1103. [PMID: 32100530 DOI: 10.1021/acs.biochem.0c00043] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Epigallocatechin-3-gallate (EGCG) is a catechin found in green tea that can inhibit the amyloid formation of a wide variety of proteins. EGCG's ability to prevent or redirect the amyloid formation of so many proteins may reflect a common mechanism of action, and thus, greater molecular-level insight into how it exerts its effect could have broad implications. Here, we investigate the molecular details of EGCG's inhibition of the protein β-2-microglobulin (β2m), which forms amyloids in patients undergoing long-term dialysis treatment. Using size-exclusion chromatography and a collection of mass spectrometry-based techniques, we find that EGCG prevents Cu(II)-induced β2m amyloid formation by diverting the normal progression of preamyloid oligomers toward the formation of spherical, redissolvable aggregates. EGCG exerts its effect by binding with a micromolar affinity (Kd ≈ 5 μM) to the β2m monomer on the edge of two β-sheets near the N-terminus. This interaction destabilizes the preamyloid dimer and prevents the formation of a tetramer species previously shown to be essential for Cu(II)-induced β2m amyloid formation. EGCG's binding at the edge of the β-sheets in β2m is consistent with a previous hypothesis that EGCG generally prevents amyloid formation by binding cross-β-sheet aggregation intermediates.
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Affiliation(s)
- Tyler M Marcinko
- Department of Chemistry, University of Massachusetts-Amherst, 374 Lederle Graduate Research Tower A, 710 North Pleasant Street, Amherst, Massachusetts 01003, United States
| | - Thomas Drews
- Department of Chemistry, University of Massachusetts-Amherst, 374 Lederle Graduate Research Tower A, 710 North Pleasant Street, Amherst, Massachusetts 01003, United States
| | - Tianying Liu
- Department of Chemistry, University of Massachusetts-Amherst, 374 Lederle Graduate Research Tower A, 710 North Pleasant Street, Amherst, Massachusetts 01003, United States
| | - Richard W Vachet
- Department of Chemistry, University of Massachusetts-Amherst, 374 Lederle Graduate Research Tower A, 710 North Pleasant Street, Amherst, Massachusetts 01003, United States
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22
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Ziemianowicz DS, MacCallum JL, Schriemer DC. Correlation between Labeling Yield and Surface Accessibility in Covalent Labeling Mass Spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2020; 31:207-216. [PMID: 32031402 DOI: 10.1021/jasms.9b00083] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The functional properties of a protein are strongly influenced by its topography, or the solvent-facing contour map of its surface. Together with crosslinking, covalent labeling mass spectrometry (CL-MS) has the potential to contribute topographical data through the measurement of surface accessibility. However, recent efforts to correlate measures of surface accessibility with labeling yield have been met with mixed success. Most applications of CL-MS involve differential analysis of protein interactions (i.e., footprinting experiments) where such inconsistencies have limited effect. Extending CL-MS into structural analysis requires an improved evaluation of the relationship between labeling and surface exposure. In this study, we applied recently developed diazirine reagents to obtain deep coverage of the large motor domain of Eg5 (a mitotic kinesin), and together with computational methods we correlated labeling yields with accessibility data in a number of ways. We observe that correlations can indeed be seen at a local structural level, but these correlations do not extend across the structure. The lack of correlation arises from the influence of protein dynamics and chemical composition on reagent partitioning and, thus, also on labeling yield. We conclude that our use of CL-MS data should be considered in light of "chemical accessibility" rather than "solvent accessibility" and suggest that CL-MS data would be a useful tool in the fundamental study of protein-solute interactions.
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Affiliation(s)
- Daniel S Ziemianowicz
- Department of Biochemistry and Molecular Biology , University of Calgary , Calgary , Alberta , Canada T2N 4N1
- Robson DNA Science Centre, Arnie Charbonneau Cancer Institute , University of Calgary , Calgary , Alberta , Canada T2N 4N1
| | - Justin L MacCallum
- Department of Chemistry , University of Calgary , Calgary , Alberta , Canada T2N 4N1
| | - David C Schriemer
- Department of Biochemistry and Molecular Biology , University of Calgary , Calgary , Alberta , Canada T2N 4N1
- Robson DNA Science Centre, Arnie Charbonneau Cancer Institute , University of Calgary , Calgary , Alberta , Canada T2N 4N1
- Department of Chemistry , University of Calgary , Calgary , Alberta , Canada T2N 4N1
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23
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De Simone A, Naldi M, Tedesco D, Bartolini M, Davani L, Andrisano V. Advanced analytical methodologies in Alzheimer’s disease drug discovery. J Pharm Biomed Anal 2020; 178:112899. [DOI: 10.1016/j.jpba.2019.112899] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 09/25/2019] [Accepted: 09/26/2019] [Indexed: 12/13/2022]
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24
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Liu T, Limpikirati P, Vachet RW. Synergistic Structural Information from Covalent Labeling and Hydrogen-Deuterium Exchange Mass Spectrometry for Protein-Ligand Interactions. Anal Chem 2019; 91:15248-15254. [PMID: 31664819 DOI: 10.1021/acs.analchem.9b04257] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Hydrogen-deuterium exchange (HDX) mass spectrometry (MS) and covalent labeling (CL) MS are typically considered to be complementary methods for protein structural analysis, because one probes the protein backbone, while the other probes side chains. For protein-ligand interactions, we demonstrate in this work that the two labeling techniques can provide synergistic structural information about protein-ligand binding when reagents like diethylpyrocarbonate (DEPC) are used for CL because of the differences in the reaction rates of DEPC and HDX. Using three model protein-ligand systems, we show that the slower time scale for DEPC labeling makes it only sensitive to changes in solvent accessibility and insensitive to changes in protein structural fluctuations, whereas HDX is sensitive to changes in both solvent accessibility and structural fluctuations. When used together, the two methods more clearly reveal binding sites and ligand-induced changes to structural fluctuations that are distant from the binding site, which is more comprehensive information than either technique alone can provide. We predict that these two methods will find widespread usage together for more deeply understanding protein-ligand interactions.
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Affiliation(s)
- Tianying Liu
- Department of Chemistry , University of Massachusetts , Amherst , Massachusetts 01003 , United States
| | - Patanachai Limpikirati
- Department of Chemistry , University of Massachusetts , Amherst , Massachusetts 01003 , United States
| | - Richard W Vachet
- Department of Chemistry , University of Massachusetts , Amherst , Massachusetts 01003 , United States
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25
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Limpikirati P, Pan X, Vachet RW. Covalent Labeling with Diethylpyrocarbonate: Sensitive to the Residue Microenvironment, Providing Improved Analysis of Protein Higher Order Structure by Mass Spectrometry. Anal Chem 2019; 91:8516-8523. [PMID: 31150223 DOI: 10.1021/acs.analchem.9b01732] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Covalent labeling with mass spectrometry is increasingly being used for the structural analysis of proteins. Diethylpyrocarbonate (DEPC) is a simple to use, commercially available covalent labeling reagent that can readily react with a range of nucleophilic residues in proteins. We find that in intact proteins weakly nucleophilic side chains (Ser, Thr, and Tyr) can be modified by DEPC in addition to other residues such as His, Lys, and Cys, providing very good structural resolution. We hypothesize that the microenvironment around these side chains, as formed by a protein's higher order structure, tunes their reactivity such that they can be labeled. To test this hypothesis, we compare DEPC labeling reactivity of Ser, Thr, and Tyr residues in intact proteins with peptide fragments from the same proteins. Results indicate that these residues almost never react with DEPC in free peptides, supporting the hypothesis that a protein's local microenvironment tunes the reactivity of these residues. From a close examination of the structural features near the reactive residues, we find that nearby hydrophobic residues are essential, suggesting that the enhanced reactivity of certain Ser, Thr, and Tyr residues occurs due to higher local concentrations of DEPC.
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Affiliation(s)
- Patanachai Limpikirati
- Department of Chemistry , University of Massachusetts Amherst , Amherst , Massachusetts 01003 , United States
| | - Xiao Pan
- Department of Chemistry , University of Massachusetts Amherst , Amherst , Massachusetts 01003 , United States
| | - Richard W Vachet
- Department of Chemistry , University of Massachusetts Amherst , Amherst , Massachusetts 01003 , United States
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26
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Limpikirati P, Hale JE, Hazelbaker M, Huang Y, Jia Z, Yazdani M, Graban EM, Vaughan RC, Vachet RW. Covalent labeling and mass spectrometry reveal subtle higher order structural changes for antibody therapeutics. MAbs 2019; 11:463-476. [PMID: 30636503 PMCID: PMC6512938 DOI: 10.1080/19420862.2019.1565748] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2018] [Revised: 12/24/2018] [Accepted: 01/03/2019] [Indexed: 01/26/2023] Open
Abstract
Monoclonal antibodies are among the fastest growing therapeutics in the pharmaceutical industry. Detecting higher-order structure changes of antibodies upon storage or mishandling, however, is a challenging problem. In this study, we describe the use of diethylpyrocarbonate (DEPC)-based covalent labeling (CL) - mass spectrometry (MS) to detect conformational changes caused by heat stress, using rituximab as a model system. The structural resolution obtained from DEPC CL-MS is high enough to probe subtle conformation changes that are not detectable by common biophysical techniques. Results demonstrate that DEPC CL-MS can detect and identify sites of conformational changes at the temperatures below the antibody melting temperature (e.g., 55 ᴼC). The observed labeling changes at lower temperatures are validated by activity assays that indicate changes in the Fab region. At higher temperatures (e.g., 65 ᴼC), conformational changes and aggregation sites are identified from changes in CL levels, and these results are confirmed by complementary biophysical and activity measurements. Given the sensitivity and simplicity of DEPC CL-MS, this method should be amenable to the structural investigations of other antibody therapeutics.
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Affiliation(s)
| | | | - Mark Hazelbaker
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN, USA
| | - Yongbo Huang
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN, USA
| | - Zhiguang Jia
- Department of Chemistry, University of Massachusetts Amherst, Amherst, MA, USA
| | - Mahdieh Yazdani
- Department of Chemistry, University of Massachusetts Amherst, Amherst, MA, USA
| | | | - Robert C. Vaughan
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN, USA
| | - Richard W. Vachet
- Department of Chemistry, University of Massachusetts Amherst, Amherst, MA, USA
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Kaur U, Johnson DT, Chea EE, Deredge DJ, Espino JA, Jones LM. Evolution of Structural Biology through the Lens of Mass Spectrometry. Anal Chem 2019; 91:142-155. [PMID: 30457831 PMCID: PMC6472977 DOI: 10.1021/acs.analchem.8b05014] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Upneet Kaur
- Department of Pharmaceutical Sciences, University of Maryland, Baltimore, Maryland 21201, United States
| | - Danté T. Johnson
- Department of Pharmaceutical Sciences, University of Maryland, Baltimore, Maryland 21201, United States
| | - Emily E. Chea
- Department of Pharmaceutical Sciences, University of Maryland, Baltimore, Maryland 21201, United States
| | - Daniel J. Deredge
- Department of Pharmaceutical Sciences, University of Maryland, Baltimore, Maryland 21201, United States
| | - Jessica A. Espino
- Department of Pharmaceutical Sciences, University of Maryland, Baltimore, Maryland 21201, United States
| | - Lisa M. Jones
- Department of Pharmaceutical Sciences, University of Maryland, Baltimore, Maryland 21201, United States
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Kaur U, Johnson DT, Chea EE, Deredge DJ, Espino JA, Jones LM. Evolution of Structural Biology through the Lens of Mass Spectrometry. Anal Chem 2019; 91:142-155. [PMID: 30457831 DOI: 10.1021/acs.analchem.1028b05014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Affiliation(s)
- Upneet Kaur
- Department of Pharmaceutical Sciences , University of Maryland , Baltimore , Maryland 21201 , United States
| | - Danté T Johnson
- Department of Pharmaceutical Sciences , University of Maryland , Baltimore , Maryland 21201 , United States
| | - Emily E Chea
- Department of Pharmaceutical Sciences , University of Maryland , Baltimore , Maryland 21201 , United States
| | - Daniel J Deredge
- Department of Pharmaceutical Sciences , University of Maryland , Baltimore , Maryland 21201 , United States
| | - Jessica A Espino
- Department of Pharmaceutical Sciences , University of Maryland , Baltimore , Maryland 21201 , United States
| | - Lisa M Jones
- Department of Pharmaceutical Sciences , University of Maryland , Baltimore , Maryland 21201 , United States
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Huang T, Armbruster MR, Coulton JB, Edwards JL. Chemical Tagging in Mass Spectrometry for Systems Biology. Anal Chem 2018; 91:109-125. [DOI: 10.1021/acs.analchem.8b04951] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Tianjiao Huang
- Department of Chemistry, Saint Louis University, 3501 Laclede Avenue, St. Louis, Missouri 63103, United States
| | - Michael R. Armbruster
- Department of Chemistry, Saint Louis University, 3501 Laclede Avenue, St. Louis, Missouri 63103, United States
| | - John B. Coulton
- Department of Chemistry, Saint Louis University, 3501 Laclede Avenue, St. Louis, Missouri 63103, United States
| | - James L. Edwards
- Department of Chemistry, Saint Louis University, 3501 Laclede Avenue, St. Louis, Missouri 63103, United States
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Giorgetti S, Greco C, Tortora P, Aprile FA. Targeting Amyloid Aggregation: An Overview of Strategies and Mechanisms. Int J Mol Sci 2018; 19:E2677. [PMID: 30205618 PMCID: PMC6164555 DOI: 10.3390/ijms19092677] [Citation(s) in RCA: 87] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Revised: 09/02/2018] [Accepted: 09/05/2018] [Indexed: 12/26/2022] Open
Abstract
Amyloids result from the aggregation of a set of diverse proteins, due to either specific mutations or promoting intra- or extra-cellular conditions. Structurally, they are rich in intermolecular β-sheets and are the causative agents of several diseases, both neurodegenerative and systemic. It is believed that the most toxic species are small aggregates, referred to as oligomers, rather than the final fibrillar assemblies. Their mechanisms of toxicity are mostly mediated by aberrant interactions with the cell membranes, with resulting derangement of membrane-related functions. Much effort is being exerted in the search for natural antiamyloid agents, and/or in the development of synthetic molecules. Actually, it is well documented that the prevention of amyloid aggregation results in several cytoprotective effects. Here, we portray the state of the art in the field. Several natural compounds are effective antiamyloid agents, notably tetracyclines and polyphenols. They are generally non-specific, as documented by their partially overlapping mechanisms and the capability to interfere with the aggregation of several unrelated proteins. Among rationally designed molecules, we mention the prominent examples of β-breakers peptides, whole antibodies and fragments thereof, and the special case of drugs with contrasting transthyretin aggregation. In this framework, we stress the pivotal role of the computational approaches. When combined with biophysical methods, in several cases they have helped clarify in detail the protein/drug modes of interaction, which makes it plausible that more effective drugs will be developed in the future.
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Affiliation(s)
- Sofia Giorgetti
- Department of Molecular Medicine, Institute of Biochemistry, University of Pavia, Via Taramelli 3b, 27100 Pavia, Italy.
| | - Claudio Greco
- Department of Earth and Environmental Sciences, University of Milano-Bicocca, Piazza della Scienza 1, 20126 Milano, Italy.
| | - Paolo Tortora
- Department of Biotechnologies and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, 20126 Milano, Italy.
- Milan Center for Neuroscience (Neuro-MI), 20126 Milano, Italy.
| | - Francesco Antonio Aprile
- Centre for Misfolding Diseases, Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, UK.
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Limpikirati P, Liu T, Vachet RW. Covalent labeling-mass spectrometry with non-specific reagents for studying protein structure and interactions. Methods 2018; 144:79-93. [PMID: 29630925 PMCID: PMC6051898 DOI: 10.1016/j.ymeth.2018.04.002] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2018] [Revised: 04/03/2018] [Accepted: 04/04/2018] [Indexed: 12/13/2022] Open
Abstract
Using mass spectrometry (MS) to obtain information about a higher order structure of protein requires that a protein's structural properties are encoded into the mass of that protein. Covalent labeling (CL) with reagents that can irreversibly modify solvent accessible amino acid side chains is an effective way to encode structural information into the mass of a protein, as this information can be read-out in a straightforward manner using standard MS-based proteomics techniques. The differential reactivity of proteins under two or more conditions can be used to distinguish protein topologies, conformations, and/or binding sites. CL-MS methods have been effectively used for the structural analysis of proteins and protein complexes, particularly for systems that are difficult to study by other more traditional biochemical techniques. This review provides an overview of the non-specific CL approaches that have been combined with MS with a particular emphasis on the reagents that are commonly used, including hydroxyl radicals, carbenes, and diethylpyrocarbonate. We describe the reagent and protein factors that affect the reactivity of amino acid side chains. We also include details about experimental design and workflow, data analysis, recent applications, and some future prospects of CL-MS methods.
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Affiliation(s)
| | - Tianying Liu
- Department of Chemistry, University of Massachusetts Amherst, MA 01003, United States
| | - Richard W Vachet
- Department of Chemistry, University of Massachusetts Amherst, MA 01003, United States.
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