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Sternicki LM, Poulsen SA. Fragment-based drug discovery campaigns guided by native mass spectrometry. RSC Med Chem 2024; 15:2270-2285. [PMID: 39026646 PMCID: PMC11253872 DOI: 10.1039/d4md00273c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2024] [Accepted: 05/19/2024] [Indexed: 07/20/2024] Open
Abstract
Native mass spectrometry (nMS) is well established as a biophysical technique for characterising biomolecules and their interactions with endogenous or investigational small molecule ligands. The high sensitivity mass measurements make nMS particularly well suited for applications in fragment-based drug discovery (FBDD) screening campaigns where the detection of weakly binding ligands to a target biomolecule is crucial. We first reviewed the contributions of nMS to guiding FBDD hit identification in 2013, providing a comprehensive perspective on the early adoption of nMS for fragment screening. Here we update this initial progress with a focus on contributions of nMS that have guided FBDD for the period 2014 until end of 2023. We highlight the development of nMS adoption in FBDD in the context of other biophysical fragment screening techniques. We also discuss the roadmap for increased adoption of nMS for fragment screening beyond soluble proteins, including for guiding the discovery of fragments supporting advances in PROTAC discovery, RNA-binding small molecules and covalent therapeutic drug discovery.
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Affiliation(s)
- Louise M Sternicki
- Griffith Institute for Drug Discovery, Griffith University Nathan Brisbane Queensland 4111 Australia
- ARC Centre for Fragment-Based Design Australia
| | - Sally-Ann Poulsen
- Griffith Institute for Drug Discovery, Griffith University Nathan Brisbane Queensland 4111 Australia
- ARC Centre for Fragment-Based Design Australia
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2
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Sternicki LM, Poulsen SA. Native Mass Spectrometry: Insights and Opportunities for Targeted Protein Degradation. Anal Chem 2023; 95:18655-18666. [PMID: 38090751 DOI: 10.1021/acs.analchem.3c03853] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2023]
Abstract
Native mass spectrometry (nMS) is one of the most powerful biophysical methods for the direct observation of noncovalent protein interactions with both small molecules and other proteins. With the advent of targeted protein degradation (TPD), nMS is now emerging as a compelling approach to characterize the multiple fundamental interactions that underpin the TPD mechanism. Specifically, nMS enables the simultaneous observation of the multiple binary and ternary complexes [i.e., all combinations of E3 ligase, target protein of interest, and small molecule proximity-inducing reagents (such as PROteolysis TArgeting Chimeras (PROTACs) and molecular glues)], formed as part of the TPD equilibrium; this is not possible with any other biophysical method. In this paper we overview the proof-of-concept applications of nMS within the field of TPD and demonstrate how it is providing researchers with critical insight into the systems under study. We also provide an outlook on the scope and future opportunities offered by nMS as a core and agnostic biophysical tool for advancing research developments in TPD.
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Affiliation(s)
- Louise M Sternicki
- Griffith Institute for Drug Discovery, Griffith University, Nathan, Brisbane, Queensland 4111, Australia
| | - Sally-Ann Poulsen
- Griffith Institute for Drug Discovery, Griffith University, Nathan, Brisbane, Queensland 4111, Australia
- School of Environment and Science, Griffith University, Nathan, Brisbane, Queensland 4111, Australia
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3
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Götze M, Polewski L, Bechtella L, Pagel K. A 3D-Printed Offline Nano-ESI Source for Bruker MS Instruments. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2023; 34:2403-2406. [PMID: 37602654 PMCID: PMC10557379 DOI: 10.1021/jasms.3c00214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 07/27/2023] [Accepted: 07/31/2023] [Indexed: 08/22/2023]
Abstract
Nanoelectrospray ionization (nano-ESI) is a highly efficient and a widely used technique for the ionization of minute amounts of analyte. Offline nano-ESI sources are convenient for the direct infusion of complex mixtures that suffer from high matrix content and are crucial for the native mass spectrometric analysis of proteins. For Bruker instruments, no such source is readily available. Here we close this gap and present a 3D-printable nano-ESI source for Bruker instruments, which can be assembled by anyone with access to 3D printers. The source can be fitted to any Bruker mass spectrometer with an ionBooster ESI source and only requires minor, reversible changes to the original Bruker hardware. The general utility was demonstrated by recording high-resolution MS spectra of small molecules, intact proteins, as well as complex biological samples in negative and positive ion mode on two different Bruker instruments.
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Affiliation(s)
- Michael Götze
- Institut für Chemie und Biochemie, Freie Universität Berlin, 14195 Berlin, Germany
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, 14195 Berlin, Germany
| | - Lukasz Polewski
- Institut für Chemie und Biochemie, Freie Universität Berlin, 14195 Berlin, Germany
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, 14195 Berlin, Germany
| | - Leïla Bechtella
- Institut für Chemie und Biochemie, Freie Universität Berlin, 14195 Berlin, Germany
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, 14195 Berlin, Germany
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4
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Kaeslin J, Brunner C, Ghiasikhou S, Schneider G, Zenobi R. Bioaffinity Screening with a Rapid and Sample-Efficient Autosampler for Native Electrospray Ionization Mass Spectrometry. Anal Chem 2021; 93:13342-13350. [PMID: 34546705 DOI: 10.1021/acs.analchem.1c03130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Fast and efficient handling of ligands and biological targets are required in bioaffinity screening based on native electrospray ionization mass spectrometry (ESI-MS). We use a prototype microfluidic autosampler, called the "gap sampler", to sequentially mix and electrospray individual small molecule ligands together with a target protein and compare the screening results with data from thermal shift assay and surface plasmon resonance. In a first round, all three techniques were used for a screening of 110 ligands against bovine carbonic anhydrase II, which resulted in five mutual hits and some false positives with ESI-MS presumably due to the high ligand concentration or interferences from dimethyl sulfoxide. In a second round, 33 compounds were screened in lower concentrations and in a less complex matrix, resulting in only true positives with ESI-MS. Within a cycle time of 30 s, dissociation constants were determined within an order of magnitude accuracy consuming only 5 pmol of ligand and less than 15 pmol of protein per screened compound. In a third round, dissociation constants of five compounds were accurately determined in a titration experiment. Thus, the gap sampler can rapidly and efficiently be used for high-throughput screening.
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Affiliation(s)
- Jérôme Kaeslin
- Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 3, CH-8093 Zurich, Switzerland
| | - Cyrill Brunner
- Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 3, CH-8093 Zurich, Switzerland
| | - Sahar Ghiasikhou
- Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 3, CH-8093 Zurich, Switzerland
| | - Gisbert Schneider
- Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 3, CH-8093 Zurich, Switzerland
| | - Renato Zenobi
- Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 3, CH-8093 Zurich, Switzerland
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5
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Bennett JL, Nguyen GTH, Donald WA. Protein-Small Molecule Interactions in Native Mass Spectrometry. Chem Rev 2021; 122:7327-7385. [PMID: 34449207 DOI: 10.1021/acs.chemrev.1c00293] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Small molecule drug discovery has been propelled by the continual development of novel scientific methodologies to occasion therapeutic advances. Although established biophysical methods can be used to obtain information regarding the molecular mechanisms underlying drug action, these approaches are often inefficient, low throughput, and ineffective in the analysis of heterogeneous systems including dynamic oligomeric assemblies and proteins that have undergone extensive post-translational modification. Native mass spectrometry can be used to probe protein-small molecule interactions with unprecedented speed and sensitivity, providing unique insights into polydisperse biomolecular systems that are commonly encountered during the drug discovery process. In this review, we describe potential and proven applications of native MS in the study of interactions between small, drug-like molecules and proteins, including large multiprotein complexes and membrane proteins. Approaches to quantify the thermodynamic and kinetic properties of ligand binding are discussed, alongside a summary of gas-phase ion activation techniques that have been used to interrogate the structure of protein-small molecule complexes. We additionally highlight some of the key areas in modern drug design for which native mass spectrometry has elicited significant advances. Future developments and applications of native mass spectrometry in drug discovery workflows are identified, including potential pathways toward studying protein-small molecule interactions on a whole-proteome scale.
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Affiliation(s)
- Jack L Bennett
- School of Chemistry, University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Giang T H Nguyen
- School of Chemistry, University of New South Wales, Sydney, New South Wales 2052, Australia
| | - William A Donald
- School of Chemistry, University of New South Wales, Sydney, New South Wales 2052, Australia
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6
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Sternicki LM, Nonomiya J, Liu M, Mulvihill MM, Quinn RJ. Native Mass Spectrometry for the Study of PROTAC GNE-987-Containing Ternary Complexes. ChemMedChem 2021; 16:2206-2210. [PMID: 33792163 PMCID: PMC8359942 DOI: 10.1002/cmdc.202100113] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Indexed: 12/14/2022]
Abstract
PROteolysis TArgeting Chimeras (PROTACs) promote the degradation, rather than inhibition, of a drug target as a mechanism for therapeutic treatment. Bifunctional PROTAC molecules allow simultaneous binding of both the target protein and an E3-Ubiquitin ligase, bringing the two proteins into close spatial proximity to allow ubiquitinylation and degradation of the target protein via the cell's endogenous protein degradation pathway. We utilized native mass spectrometry (MS) to study the ternary complexes promoted by the previously reported PROTAC GNE-987 between Brd4 bromodomains 1 and 2, and Von Hippel Lindeau E3-Ubiquitin Ligase. Native MS at high resolution allowed us to measure ternary complex formation as a function of PROTAC concentration to provide a measure of complex affinity and stability, whilst simultaneously measuring other intermediate protein species. Native MS provides a high-throughput, low sample consumption, direct screening method to measure ternary complexes for PROTAC development.
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Affiliation(s)
- Louise M. Sternicki
- Griffith Institute for Drug DiscoveryGriffith University46 Don Young RoadNathanQLD 4111Australia
| | - Jim Nonomiya
- Genentech Inc.1 DNA WaySouth San FranciscoCA 94080USA
| | - Miaomiao Liu
- Griffith Institute for Drug DiscoveryGriffith University46 Don Young RoadNathanQLD 4111Australia
| | | | - Ronald J. Quinn
- Griffith Institute for Drug DiscoveryGriffith University46 Don Young RoadNathanQLD 4111Australia
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7
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Daems E, Moro G, Berghmans H, Moretto LM, Dewilde S, Angelini A, Sobott F, De Wael K. Native mass spectrometry for the design and selection of protein bioreceptors for perfluorinated compounds. Analyst 2021; 146:2065-2073. [PMID: 33538714 DOI: 10.1039/d0an02005b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Biosensing platforms are answering the increasing demand for analytical tools for environmental monitoring of small molecules, such as per- and polyfluoroalkyl substances (PFAS). By transferring toxicological findings in bioreceptor design we can develop innovative pathways for biosensor design. Indeed, toxicological studies provide fundamental information about PFAS-biomolecule complexes that can help evaluate the applicability of the latter as bioreceptors. The toolbox of native mass spectrometry (MS) can support this evaluation, as shown by the two case studies reported in this work. The analysis of model proteins' (i.e. albumin, haemoglobin, cytochrome c and neuroglobin) interactions with well-known PFAS, such as perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), demonstrated the potential of this native MS screening approach. In the first case study, untreated albumin and delipidated albumin were compared in the presence and absence of PFOA confirming that the delipidation step increases albumin affinity for PFOA without affecting protein stability. In the second case study, the applicability of our methodology to identify potential bioreceptors for PFOS/PFOA was extended to other proteins. Structurally related haemoglobin and neuroglobin revealed a 1 : 1 complex, whereas no binding was observed for cytochrome c. These studies have value as a proof-of-concept for a general application of native MS to identify bioreceptors for toxic compounds.
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Affiliation(s)
- Elise Daems
- AXES Research Group, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium.
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Tao Y, Yan J, Cai B. LABEL-FREE BIO-AFFINITY MASS SPECTROMETRY FOR SCREENING AND LOCATING BIOACTIVE MOLECULES. MASS SPECTROMETRY REVIEWS 2021; 40:53-71. [PMID: 31755145 DOI: 10.1002/mas.21613] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Accepted: 11/04/2019] [Indexed: 06/10/2023]
Abstract
Despite the recent increase in the development of bioactive molecules in the drug industry, the enormous chemical space and lack of productivity are still important issues. Additional alternative approaches to screen and locate bioactive molecules are urgently needed. Label-free bio-affinity mass spectrometry (BA-MS) provides opportunities for the discovery and development of innovative drugs. This review provides a comprehensive portrayal of BA-MS techniques and of their applications in screening and locating bioactive molecules. After introducing the basic principles, alongside some application notes, the current state-of-the-art of BA-MS-assisted drug discovery is discussed, including native MS, size-exclusion chromatography-MS, ultrafiltration-MS, solid-phase micro-extraction-MS, and cell membrane chromatography-MS. Finally, several challenges and limitations of the current methods are summarized, with a view to potential future directions for BA-MS-assisted drug discovery. © 2019 John Wiley & Sons Ltd. Mass Spec Rev.
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Affiliation(s)
- Yi Tao
- College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou, 310032, PR China
| | - Jizhong Yan
- College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou, 310032, PR China
| | - Baochang Cai
- Jiangsu Key Laboratory of Chinese Medicine Processing, Nanjing University of Chinese Medicine, Nanjing, 210023, PR China
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Bai N, Roder H, Dickson A, Karanicolas J. Isothermal Analysis of ThermoFluor Data can readily provide Quantitative Binding Affinities. Sci Rep 2019; 9:2650. [PMID: 30804351 PMCID: PMC6389909 DOI: 10.1038/s41598-018-37072-x] [Citation(s) in RCA: 72] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Accepted: 11/30/2018] [Indexed: 01/20/2023] Open
Abstract
Differential scanning fluorimetry (DSF), also known as ThermoFluor or Thermal Shift Assay, has become a commonly-used approach for detecting protein-ligand interactions, particularly in the context of fragment screening. Upon binding to a folded protein, most ligands stabilize the protein; thus, observing an increase in the temperature at which the protein unfolds as a function of ligand concentration can serve as evidence of a direct interaction. While experimental protocols for this assay are well-developed, it is not straightforward to extract binding constants from the resulting data. Because of this, DSF is often used to probe for an interaction, but not to quantify the corresponding binding constant (Kd). Here, we propose a new approach for analyzing DSF data. Using unfolding curves at varying ligand concentrations, our "isothermal" approach collects from these the fraction of protein that is folded at a single temperature (chosen to be temperature near the unfolding transition). This greatly simplifies the subsequent analysis, because it circumvents the complicating temperature dependence of the binding constant; the resulting constant-temperature system can then be described as a pair of coupled equilibria (protein folding/unfolding and ligand binding/unbinding). The temperature at which the binding constants are determined can also be tuned, by adding chemical denaturants that shift the protein unfolding temperature. We demonstrate the application of this isothermal analysis using experimental data for maltose binding protein binding to maltose, and for two carbonic anhydrase isoforms binding to each of four inhibitors. To facilitate adoption of this new approach, we provide a free and easy-to-use Python program that analyzes thermal unfolding data and implements the isothermal approach described herein ( https://sourceforge.net/projects/dsf-fitting ).
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Affiliation(s)
- Nan Bai
- Program in Molecular Therapeutics, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS, 66045, USA
| | - Heinrich Roder
- Program in Molecular Therapeutics, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
| | - Alex Dickson
- Department of Biochemistry & Molecular Biology and Department of Computational Mathematics, Science and Engineering, Michigan State University, East Lansing, MI, 48824, USA
| | - John Karanicolas
- Program in Molecular Therapeutics, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA.
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Root K, Barylyuk K, Schwab A, Thelemann J, Illarionov B, Geist JG, Gräwert T, Bacher A, Fischer M, Diederich F, Zenobi R. Aryl bis-sulfonamides bind to the active site of a homotrimeric isoprenoid biosynthesis enzyme IspF and extract the essential divalent metal cation cofactor. Chem Sci 2018; 9:5976-5986. [PMID: 30079212 PMCID: PMC6050538 DOI: 10.1039/c8sc00814k] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Accepted: 06/17/2018] [Indexed: 12/22/2022] Open
Abstract
Characterizing the mode of action of non-covalent inhibitors in multisubunit enzymes often presents a great challenge. Most of the conventionally used methods are based on ensemble measurements of protein-ligand binding in bulk solution. They often fail to accurately describe multiple binding processes occurring in such systems. Native electrospray ionization mass spectrometry (ESI-MS) of intact protein complexes is a direct, label-free approach that can render the entire distribution of ligand-bound states in multimeric protein complexes. Here we apply native ESI-MS to comprehensively characterize the isoprenoid biosynthesis enzyme IspF from Arabidopsis thaliana, an example of a homomeric protein complex with multiple binding sites for several types of ligands, including a metal cofactor and a synthetic inhibitor. While standard biophysical techniques failed to reveal the mode of action of recently discovered aryl-sulfonamide-based inhibitors of AtIspF, direct native ESI-MS titrations of the protein with the ligands and ligand competition assays allowed us to accurately capture the solution-phase protein-ligand binding equilibria in full complexity and detail. Based on these combined with computational modeling, we propose a mechanism of AtIspF inhibition by aryl bis-sulfonamides that involves both the competition with the substrate for the ligand-binding pocket and the extraction of Zn2+ from the enzyme active site. This inhibition mode is therefore mixed competitive and non-competitive, the latter exerting a key inhibitory effect on the enzyme activity. The results of our study deliver a profound insight into the mechanisms of AtIspF action and inhibition, open new perspectives for designing inhibitors of this important drug target, and demonstrate the applicability and value of the native ESI-MS approach for deep analysis of complex biomolecular binding equilibria.
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Affiliation(s)
- Katharina Root
- Department of Chemistry and Applied Biosciences , ETH Zurich , Zurich , Switzerland .
| | - Konstantin Barylyuk
- Department of Chemistry and Applied Biosciences , ETH Zurich , Zurich , Switzerland .
| | - Anatol Schwab
- Department of Chemistry and Applied Biosciences , ETH Zurich , Zurich , Switzerland .
| | - Jonas Thelemann
- Department of Chemistry and Applied Biosciences , ETH Zurich , Zurich , Switzerland .
| | - Boris Illarionov
- Hamburg School of Food Science , University of Hamburg , Hamburg , Germany
| | - Julie G Geist
- Department of Chemistry and Applied Biosciences , ETH Zurich , Zurich , Switzerland .
| | - Tobias Gräwert
- Hamburg School of Food Science , University of Hamburg , Hamburg , Germany
| | - Adelbert Bacher
- Department of Chemistry , Technical University of Munich , Garching , Germany
| | - Markus Fischer
- Hamburg School of Food Science , University of Hamburg , Hamburg , Germany
| | - François Diederich
- Department of Chemistry and Applied Biosciences , ETH Zurich , Zurich , Switzerland .
| | - Renato Zenobi
- Department of Chemistry and Applied Biosciences , ETH Zurich , Zurich , Switzerland .
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11
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MS methods to study macromolecule-ligand interaction: Applications in drug discovery. Methods 2018; 144:152-174. [PMID: 29890284 DOI: 10.1016/j.ymeth.2018.06.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 06/01/2018] [Accepted: 06/03/2018] [Indexed: 12/12/2022] Open
Abstract
The interaction of small compounds (i.e. ligands) with macromolecules or macromolecule assemblies (i.e. targets) is the mechanism of action of most of the drugs available today. Mass spectrometry is a popular technique for the interrogation of macromolecule-ligand interactions and therefore is also widely used in drug discovery and development. Thanks to its versatility, mass spectrometry is used for multiple purposes such as biomarker screening, identification of the mechanism of action, ligand structure optimization or toxicity assessment. The evolution and automation of the instruments now allows the development of high throughput methods with high sensitivity and a minimized false discovery rate. Herein, all these approaches are described with a focus on the methods for studying macromolecule-ligand interaction aimed at defining the structure-activity relationships of drug candidates, along with their mechanism of action, metabolism and toxicity.
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12
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Chingin K, Barylyuk K. Charge-State-Dependent Variation of Signal Intensity Ratio between Unbound Protein and Protein-Ligand Complex in Electrospray Ionization Mass Spectrometry: The Role of Solvent-Accessible Surface Area. Anal Chem 2018; 90:5521-5528. [PMID: 29653057 DOI: 10.1021/acs.analchem.7b05349] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Native electrospray ionization mass spectrometry (ESI-MS) is nowadays widely used for the direct and sensitive determination of protein complex stoichiometry and binding affinity constants ( Ka). A common yet poorly understood phenomenon in native ESI-MS is the difference between the charge-state distributions (CSDs) of the bound protein-ligand complex (PL) and unbound protein (P) signals. This phenomenon is typically attributed to experimental artifacts such as nonspecific binding or in-source dissociation and is considered highly undesirable, because the determined Ka values display strong variation with charge state. This situation raises serious concerns regarding the reliability of ESI-MS for the analysis of protein complexes. Here we demonstrate that, contrary to the common belief, the CSD difference between P and PL ions can occur without any loss of complex integrity, simply due to a change in the solvent-accessible surface area (ΔSASA) of the protein upon ligand binding in solution. The experimental CSD shifts for PL and P ions in ESI-MS are explained in relation to the magnitude of ΔSASA for diverse protein-ligand systems using a simple model based on the charged residue mechanism. Our analysis shows that the revealed ΔSASA factor should be considered rather general and be given attention for the correct spectral interpretation of protein complexes.
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Affiliation(s)
- Konstantin Chingin
- Jiangxi Key Laboratory for Mass Spectrometry and Instrumentation , East China University of Technology , Guanglan Road 418 , Nanchang , Jiangxi , China 330013
| | - Konstantin Barylyuk
- Department of Biochemistry , University of Cambridge , Hopkins Building, Tennis Court Road , Cambridge CB2 1QW , United Kingdom
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13
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Mass spectrometry for fragment screening. Essays Biochem 2017; 61:465-473. [PMID: 28986384 DOI: 10.1042/ebc20170071] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Revised: 09/12/2017] [Accepted: 09/14/2017] [Indexed: 12/31/2022]
Abstract
Fragment-based approaches in chemical biology and drug discovery have been widely adopted worldwide in both academia and industry. Fragment hits tend to interact weakly with their targets, necessitating the use of sensitive biophysical techniques to detect their binding. Common fragment screening techniques include differential scanning fluorimetry (DSF) and ligand-observed NMR. Validation and characterization of hits is usually performed using a combination of protein-observed NMR, isothermal titration calorimetry (ITC) and X-ray crystallography. In this context, MS is a relatively underutilized technique in fragment screening for drug discovery. MS-based techniques have the advantage of high sensitivity, low sample consumption and being label-free. This review highlights recent examples of the emerging use of MS-based techniques in fragment screening.
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