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Clarke R, Zeng L, Atkinson BC, Kadodwala M, Thomson AR, Sutherland A. Fluorescent carbazole-derived α-amino acids: structural mimics of tryptophan. Chem Sci 2024; 15:5944-5949. [PMID: 38665535 PMCID: PMC11040653 DOI: 10.1039/d4sc01173b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2024] [Accepted: 03/20/2024] [Indexed: 04/28/2024] Open
Abstract
Fluorescent tags are commonly used for imaging of proteins and peptides during biological events; however, the large size of dyes can disrupt protein structure and function, and typically require the use of a chemical spacer. Herein, we report the synthesis of a new class of fluorescent unnatural α-amino acid, containing carbazole side-chains designed to mimic l-tryptophan and thus, readily incorporated into peptides. The amino acids were constructed using a Negishi cross-coupling reaction as the key step and exhibited strong fluorescent emission, with high quantum yields in both organic solvents and water. Compatible with solid phase peptide synthesis, the carbazole amino acids were used to replace tryptophan in a β-hairpin model peptide and shown to be a close structural mimic with retention of conformation. They were also found to be effective fluorescent molecular reporters for biological events. Incorporation into a proline-rich ligand of the WW domain protein demonstrated that the fluorescent properties of a carbazole amino acid could be used to measure the protein-protein binding interaction of this important biological signalling process.
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Affiliation(s)
- Rebecca Clarke
- School of Chemistry, University of Glasgow Joseph Black Building, University Avenue Glasgow G12 8QQ UK
| | - Liyao Zeng
- School of Chemistry, University of Glasgow Joseph Black Building, University Avenue Glasgow G12 8QQ UK
| | - Bethany C Atkinson
- School of Chemistry, University of Glasgow Joseph Black Building, University Avenue Glasgow G12 8QQ UK
| | - Malcolm Kadodwala
- School of Chemistry, University of Glasgow Joseph Black Building, University Avenue Glasgow G12 8QQ UK
| | - Andrew R Thomson
- School of Chemistry, University of Glasgow Joseph Black Building, University Avenue Glasgow G12 8QQ UK
| | - Andrew Sutherland
- School of Chemistry, University of Glasgow Joseph Black Building, University Avenue Glasgow G12 8QQ UK
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2
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Dodds AC, Sansom HG, Magennis SW, Sutherland A. Synthesis of Thiazoloindole α-Amino Acids: Chromophores Amenable to One- and Two-Photon Induced Fluorescence. Org Lett 2023; 25:8942-8946. [PMID: 38055619 PMCID: PMC10729019 DOI: 10.1021/acs.orglett.3c03851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 12/02/2023] [Accepted: 12/05/2023] [Indexed: 12/08/2023]
Abstract
Thiazoloindole α-amino acids have been synthesized in four steps from tryptophan using a dual-catalytic thiolation reaction and a copper-mediated intramolecular N-arylation process. Late-stage diversification of the thiazoloindole core with electron-deficient aryl substituents produced chromophores that on one-photon excitation displayed blue-green emission, mega-Stokes shifts, and high quantum yields. The thiazoloindole amino acids could also be excited via two-photon absorption in the near-infrared, demonstrating their potential for biomedical imaging applications.
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Affiliation(s)
- Amy C. Dodds
- School of Chemistry, The Joseph Black
Building, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Henry G. Sansom
- School of Chemistry, The Joseph Black
Building, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Steven W. Magennis
- School of Chemistry, The Joseph Black
Building, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Andrew Sutherland
- School of Chemistry, The Joseph Black
Building, University of Glasgow, Glasgow G12 8QQ, United Kingdom
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3
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Songsri S, Harkiss AH, Sutherland A. Synthesis and Photophysical Properties of Charge-Transfer-Based Pyrimidine-Derived α-Amino Acids. J Org Chem 2023; 88:13214-13224. [PMID: 37621156 PMCID: PMC10507667 DOI: 10.1021/acs.joc.3c01437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Indexed: 08/26/2023]
Abstract
The four-step synthesis of fluorescent pyrimidine-derived α-amino acids from an l-aspartic acid derivative is described. The key synthetic steps involved preparation of ynone intermediates via the reaction of alkynyl lithium salts with a Weinreb amide, followed by an ytterbium-catalyzed heterocyclization reaction with amidines. Variation of substituents at the C2- and C4-position of the pyrimidine ring allowed tuning of the photoluminescent properties of the α-amino acids. This revealed that a combination of highly conjugated or electron-rich aryl substituents with the π-deficient pyrimidine motif resulted in fluorophores with the highest quantum yields and overall brightness. Further analysis of the most fluorogenic α-amino acid demonstrated solvatochromism and sensitivity to pH.
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Affiliation(s)
- Sineenard Songsri
- School of Chemistry, The Joseph Black Building, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Alexander H. Harkiss
- School of Chemistry, The Joseph Black Building, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Andrew Sutherland
- School of Chemistry, The Joseph Black Building, University of Glasgow, Glasgow G12 8QQ, United Kingdom
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4
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McGrory R, Clarke R, Marshall O, Sutherland A. Fluorescent α-amino acids via Heck-Matsuda reactions of phenylalanine-derived arenediazonium salts. Org Biomol Chem 2023; 21:6932-6939. [PMID: 37580965 DOI: 10.1039/d3ob01096a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/16/2023]
Abstract
The Heck-Matsuda coupling reaction of arenediazonium salts derived from L-phenylalanine with various alkenes has been developed. A two-step process involving the preparation of a tetrafluoroborate diazonium salt from a 4-aminophenylalanine derivative, followed by a palladium(0)-catalysed Heck-Matsuda coupling reaction allowed access to a range of unnatural α-amino acids with cinnamate, vinylsulfone and stilbene side-chains. Analysis of the photophysical properties of these unnatural α-amino acids demonstrated that the (E)-stilbene analogues exhibited fluorescent properties with red-shifted absorption and emission spectra and larger quantum yields than L-phenylalanine.
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Affiliation(s)
- Rochelle McGrory
- School of Chemistry, University of Glasgow, The Joseph Black Building, Glasgow, G12 8QQ, UK.
| | - Rebecca Clarke
- School of Chemistry, University of Glasgow, The Joseph Black Building, Glasgow, G12 8QQ, UK.
| | - Olivia Marshall
- School of Chemistry, University of Glasgow, The Joseph Black Building, Glasgow, G12 8QQ, UK.
| | - Andrew Sutherland
- School of Chemistry, University of Glasgow, The Joseph Black Building, Glasgow, G12 8QQ, UK.
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5
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McGrory R, Morgan DC, Jamieson AG, Sutherland A. Rotamer-Controlled Dual Emissive α-Amino Acids. Org Lett 2023; 25:5844-5849. [PMID: 37506290 PMCID: PMC10425982 DOI: 10.1021/acs.orglett.3c02112] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Indexed: 07/30/2023]
Abstract
The synthesis and photoluminescent properties of novel α-amino acids are described in which the biaryl benzotriazinone-containing chromophores were found to display dual emission fluorescence via locally excited (LE) and twisted intramolecular charge transfer (TICT) states. The intensity of each emission band could be controlled by the electronics and position of the substituents, and this led to the design of a 2-methoxyphenyl analogue that, due to twisting, displayed bright TICT fluorescence, solvatochromism, and pH sensitivity.
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Affiliation(s)
- Rochelle McGrory
- School
of Chemistry, The Joseph Black Building, University of Glasgow, Glasgow G12 8QQ, United
Kingdom
| | - Danielle C. Morgan
- School
of Chemistry, Advanced Research Centre, University of Glasgow, Glasgow G11 6EW, United
Kingdom
| | - Andrew G. Jamieson
- School
of Chemistry, Advanced Research Centre, University of Glasgow, Glasgow G11 6EW, United
Kingdom
| | - Andrew Sutherland
- School
of Chemistry, The Joseph Black Building, University of Glasgow, Glasgow G12 8QQ, United
Kingdom
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6
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Riley L, Mclay TN, Sutherland A. Synthesis and Fluorescent Properties of Alkynyl- and Alkenyl-Fused Benzotriazole-Derived α-Amino Acids. J Org Chem 2023; 88:2453-2463. [PMID: 36749161 PMCID: PMC9942204 DOI: 10.1021/acs.joc.2c02886] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Fluorescent unnatural α-amino acids are widely used as probes in chemical biology and medicinal chemistry. While a variety of structural classes have been developed, there is still a requirement for new environmentally sensitive analogues that can closely mimic proteinogenic α-amino acids. Here, we report the synthesis and fluorescent properties of highly conjugated, benzotriazole-derived α-amino acids designed to mimic l-tryptophan. Alkynyl-substituted analogues were prepared using three key steps, nucleophilic aromatic substitution with a 3-aminoalanine derivative, benzotriazole formation via a one-pot diazotization and cyclization process, and a Sonogashira cross-coupling reaction. E-Alkenyl-substituted benzotriazoles were accessed by stereoselective partial hydrogenation of the alkynes using zinc iodide and palladium catalysis. The alkynyl analogues were found to possess higher quantum yields and stronger brightness and, a solvatochromic study with the most fluorogenic α-amino acids demonstrated sensitivity to polarity.
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7
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Gupta MK, Sharma NK. A new amino acid, hybrid peptides and BODIPY analogs: synthesis and evaluation of 2-aminotroponyl-L-alanine (ATA) derivatives. Org Biomol Chem 2022; 20:9397-9407. [PMID: 36398538 DOI: 10.1039/d2ob01905a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Natural aromatic α-amino acid residues play critical roles in the structural and functional organization of proteins owing to π-interactions. Their aromatic residues are derived from benzenoid scaffolds. Non-benzenoid aromatic scaffolds such as tropone and tropolone are also constituents of troponoid natural products. Tropolone has also the ability to exhibit π-interactions along with additional hydrogen bonding. Thus, amino acids comprising troponyl could be potential building blocks of novel peptidomimetics. This report describes the synthesis of the L-aminotroponylalanine amino acid (ATA) and its unusual activity with the peptide coupling agent EDC. Importantly, its di-peptides form β-sheet/-turn type secondary structures in organic solvents owing to the troponyl residue. This amino acid is an excellent scaffold for the synthesis of fluorescent amino acids such as BODIPY amino acid analogs. Nevertheless, this amino acid and its BODIPY derivatives can enter HeLa cells without exhibiting significant cytotoxicity at low concentrations (∼50 μM). Hence, ATA and its BODIPY derivatives are promising aromatic amino acids for the construction of potential peptidomimetics and fluorescent labelling of target peptides.
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Affiliation(s)
- Manish K Gupta
- School of Chemical Sciences, National Institute of Science Education and Research (NISER)-Bhubaneswar, Jatni Campus, Bhubaneswar-752050, Odisha, India. .,HBNI-Mumbai, Mumbai, India
| | - Nagendra K Sharma
- School of Chemical Sciences, National Institute of Science Education and Research (NISER)-Bhubaneswar, Jatni Campus, Bhubaneswar-752050, Odisha, India. .,HBNI-Mumbai, Mumbai, India
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8
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Benson S, de Moliner F, Tipping W, Vendrell M. Miniaturized Chemical Tags for Optical Imaging. Angew Chem Int Ed Engl 2022; 61:e202204788. [PMID: 35704518 PMCID: PMC9542129 DOI: 10.1002/anie.202204788] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Indexed: 11/06/2022]
Abstract
Recent advances in optical bioimaging have prompted the need for minimal chemical reporters that can retain the molecular recognition properties and activity profiles of biomolecules. As a result, several methodologies to reduce the size of fluorescent and Raman labels to a few atoms (e.g., single aryl fluorophores, Raman‐active triple bonds and isotopes) and embed them into building blocks (e.g., amino acids, nucleobases, sugars) to construct native‐like supramolecular structures have been described. The integration of small optical reporters into biomolecules has also led to smart molecular entities that were previously inaccessible in an expedite manner. In this article, we review recent chemical approaches to synthesize miniaturized optical tags as well as some of their multiple applications in biological imaging.
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Affiliation(s)
- Sam Benson
- Centre for Inflammation Research The University of Edinburgh Edinburgh EH16 4TJ UK
| | - Fabio de Moliner
- Centre for Inflammation Research The University of Edinburgh Edinburgh EH16 4TJ UK
| | - William Tipping
- Centre for Molecular Nanometrology The University of Strathclyde Glasgow G1 1RD UK
| | - Marc Vendrell
- Centre for Inflammation Research The University of Edinburgh Edinburgh EH16 4TJ UK
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9
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Benson S, de Moliner F, Tipping W, Vendrell M. Miniaturized Chemical Tags for Optical Imaging. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202204788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Sam Benson
- The University of Edinburgh Centre for Inflammation Research UNITED KINGDOM
| | - Fabio de Moliner
- The University of Edinburgh Centre for Inflammation Research UNITED KINGDOM
| | - William Tipping
- University of Strathclyde Centre for Molecular Nanometrology UNITED KINGDOM
| | - Marc Vendrell
- University of Edinburgh Centre for Inflammation Research 47 Little France Crescent EH16 4TJ Edinburgh UNITED KINGDOM
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10
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McGrory R, Faggyas RJ, Sutherland A. One-pot synthesis of N-substituted benzannulated triazoles via stable arene diazonium salts. Org Biomol Chem 2021; 19:6127-6140. [PMID: 34179913 DOI: 10.1039/d1ob00968k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A mild and effective one-pot synthesis of 1,2,3-benzotriazin-4(3H)-ones and benzothiatriazine-1,1(2H)-dioxide analogues has been developed. The method involves the diazotisation and subsequent cyclisation of 2-aminobenzamides and 2-aminobenzenesulfonamides via stable diazonium salts, prepared using a polymer-supported nitrite reagent and p-tosic acid. The transformation was compatible with a wide range of aryl functional groups and amide/sulfonamide-substituents and was used for the synthesis of pharmaceutically important targets. The synthetic utility of the one-pot diazotisaton-cyclisation process was further demonstrated with the preparation of an α-amino acid containing 1,2,3-benzotriazin-4(3H)-one.
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Affiliation(s)
- Rochelle McGrory
- School of Chemistry, The Joseph Black Building, University of Glasgow, Glasgow G12 8QQ, UK.
| | - Réka J Faggyas
- School of Chemistry, The Joseph Black Building, University of Glasgow, Glasgow G12 8QQ, UK.
| | - Andrew Sutherland
- School of Chemistry, The Joseph Black Building, University of Glasgow, Glasgow G12 8QQ, UK.
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11
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Xiong Y, Shi C, Li L, Tang Y, Zhang X, Liao S, Zhang B, Sun C, Ren C. A review on recent advances in amino acid and peptide-based fluorescence and its potential applications. NEW J CHEM 2021. [DOI: 10.1039/d1nj02230j] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Fluorescence is widely used to detect functional groups and ions, and peptides are used in various fields due to their excellent biological activity.
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Affiliation(s)
- Yingshuo Xiong
- School of Chemistry and Materials Science, Ludong University, Yantai 264025, China
| | - Changxin Shi
- School of Chemistry and Materials Science, Ludong University, Yantai 264025, China
| | - Lingyi Li
- School of Chemistry and Materials Science, Ludong University, Yantai 264025, China
| | - Yuanhan Tang
- School of Chemistry and Materials Science, Ludong University, Yantai 264025, China
| | - Xin Zhang
- School of Chemistry and Materials Science, Ludong University, Yantai 264025, China
| | - Sisi Liao
- School of Chemistry and Materials Science, Ludong University, Yantai 264025, China
| | - Beibei Zhang
- School of Chemistry and Materials Science, Ludong University, Yantai 264025, China
| | - Changmei Sun
- School of Chemistry and Materials Science, Ludong University, Yantai 264025, China
| | - Chunguang Ren
- Yantai Institute of Materia Medica, Yantai 264000, China
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12
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Brittain WDG, Lloyd CM, Cobb SL. Synthesis of complex unnatural fluorine-containing amino acids. J Fluor Chem 2020; 239:109630. [PMID: 33144742 PMCID: PMC7583769 DOI: 10.1016/j.jfluchem.2020.109630] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 08/12/2020] [Accepted: 08/12/2020] [Indexed: 01/01/2023]
Abstract
The area of fluorinated amino acid synthesis has seen rapid growth over the past decade. As reports of singly fluorinated natural amino acid derivatives have grown, researchers have turned their attention to develop methodology to access complex proteinogenic examples. A variety of reaction conditions have been employed in this area, exploiting new advances in the wider synthetic community such as photocatalysis and palladium cross-coupling. In addition, novel fluorinated functional groups have also been incorporated into amino acids, with SFX and perfluoro moieties now appearing with more frequency in the literature. This review focuses on synthetic methodology for accessing complex non-proteinogenic amino acids, along with amino acids containing multiple fluorine atoms such as CF3, SF5 and perfluoroaromatic groups.
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Affiliation(s)
| | - Carissa M Lloyd
- Department of Chemistry, Durham University, Durham DH1 3LE, United Kingdom
| | - Steven L Cobb
- Department of Chemistry, Durham University, Durham DH1 3LE, United Kingdom
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13
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Fluorescent amino acids as versatile building blocks for chemical biology. Nat Rev Chem 2020; 4:275-290. [PMID: 37127957 DOI: 10.1038/s41570-020-0186-z] [Citation(s) in RCA: 91] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/14/2020] [Indexed: 12/13/2022]
Abstract
Fluorophores have transformed the way we study biological systems, enabling non-invasive studies in cells and intact organisms, which increase our understanding of complex processes at the molecular level. Fluorescent amino acids have become an essential chemical tool because they can be used to construct fluorescent macromolecules, such as peptides and proteins, without disrupting their native biomolecular properties. Fluorescent and fluorogenic amino acids with unique photophysical properties have been designed for tracking protein-protein interactions in situ or imaging nanoscopic events in real time with high spatial resolution. In this Review, we discuss advances in the design and synthesis of fluorescent amino acids and how they have contributed to the field of chemical biology in the past 10 years. Important areas of research that we review include novel methodologies to synthesize building blocks with tunable spectral properties, their integration into peptide and protein scaffolds using site-specific genetic encoding and bioorthogonal approaches, and their application to design novel artificial proteins, as well as to investigate biological processes in cells by means of optical imaging.
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