1
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Feng RR, Wang M, Zhang W, Gai F. Unnatural Amino Acids for Biological Spectroscopy and Microscopy. Chem Rev 2024; 124:6501-6542. [PMID: 38722769 DOI: 10.1021/acs.chemrev.3c00944] [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: 05/23/2024]
Abstract
Due to advances in methods for site-specific incorporation of unnatural amino acids (UAAs) into proteins, a large number of UAAs with tailored chemical and/or physical properties have been developed and used in a wide array of biological applications. In particular, UAAs with specific spectroscopic characteristics can be used as external reporters to produce additional signals, hence increasing the information content obtainable in protein spectroscopic and/or imaging measurements. In this Review, we summarize the progress in the past two decades in the development of such UAAs and their applications in biological spectroscopy and microscopy, with a focus on UAAs that can be used as site-specific vibrational, fluorescence, electron paramagnetic resonance (EPR), or nuclear magnetic resonance (NMR) probes. Wherever applicable, we also discuss future directions.
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Affiliation(s)
- Ran-Ran Feng
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Manxi Wang
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Wenkai Zhang
- Department of Physics and Applied Optics Beijing Area Major Laboratory, Beijing Normal University, Beijing 100875, China
| | - Feng Gai
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
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2
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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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3
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Antoniou AI, Pesenti M, Crespi S, Shenoy DS, Penconi M, Bossi A, Pellegrino S. Aggregation-Induced Enhanced Emission of Tetraphenylethene-phenylalanine Hybrids: Synthesis and Characterization. J Org Chem 2024; 89:4733-4740. [PMID: 38520355 DOI: 10.1021/acs.joc.3c02969] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/25/2024]
Abstract
Aggregation-induced emitting (AIE) luminophores are sensitive and easy-to-handle types of probes that allow driving a stimulus-responsive off/on optical tool through the manipulation of the aggregation behavior. In this work, tetraphenylethene (TPE)-phenylalanine derivatives, characterized by strong aggregation-induced luminescence, were obtained through Suzuki-Miyaura cross-coupling reactions. The reaction proved to be straightforwardly applicable in the single amino acid synthesis as well as in the late-stage peptide functionalization by means of both the classical solution-phase reaction and solid-phase synthesis. A comprehensive structural and analytical investigation highlighted the features driving the self-assembly process and its relationship to AIE efficiency. In particular, we showed that the simple slight (asymmetric) extension of the TPE π-systems results in more efficient and brighter emissions, with respect to the simple TPE system itself.
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Affiliation(s)
- Antonia I Antoniou
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Milano, IT-20133 Milan, Italy
| | - Michela Pesenti
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Milano, IT-20133 Milan, Italy
| | - Stefania Crespi
- Dipartimento di Scienze della Terra Ardito Desio, Università degli Studi di Milano, IT-20133 Milan, Italy
| | - Dhriti S Shenoy
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Milano, IT-20133 Milan, Italy
| | - Marta Penconi
- Istituto di Scienze e Tecnologie Chimiche "Giulio Natta" del Consiglio Nazionale delle Ricerche, CNR-SCITEC; Photoactive Molecular Materials & Devices Group, IT-20138 Milan, Italy
| | - Alberto Bossi
- Istituto di Scienze e Tecnologie Chimiche "Giulio Natta" del Consiglio Nazionale delle Ricerche, CNR-SCITEC; Photoactive Molecular Materials & Devices Group, IT-20138 Milan, Italy
| | - Sara Pellegrino
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Milano, IT-20133 Milan, Italy
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4
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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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5
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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] [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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6
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Bartolucci S, Retini M, Fanini F, Paderni D, Piersanti G. Synthesis and Fluorescence Properties of 4-Cyano and 4-Formyl Melatonin as Putative Melatoninergic Ligands. ACS OMEGA 2023; 8:22190-22194. [PMID: 37360469 PMCID: PMC10286092 DOI: 10.1021/acsomega.3c02518] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Accepted: 05/25/2023] [Indexed: 06/28/2023]
Abstract
Fluorescent ligands are imperative to many facets of chemical biology and medicinal chemistry. Herein, we report the syntheses of two fluorescent melatonin-based derivatives as potential ligands of melatonin receptors. The two compounds, namely, 4-cyano and 4-formyl melatonin (4CN-MLT and 4CHO-MLT, respectively), which differ from melatonin by only two/three atoms that are very compact in size, were prepared using the selective C3-alkylation of indoles with N-acetyl ethanolamines involving the "borrowing hydrogen" strategy. These compounds exhibit absorption/emission spectra that are red-shifted from those of melatonin. Binding studies on two melatonin receptor subtypes showed that these derivatives have a modest affinity and selectivity ratio.
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Affiliation(s)
- Silvia Bartolucci
- Department
of Biomolecular Sciences, University of
Urbino Carlo Bo, Piazza del Rinascimento 6, 61029 Urbino, Pesaro and Urbino, Italy
| | - Michele Retini
- Department
of Biomolecular Sciences, University of
Urbino Carlo Bo, Piazza del Rinascimento 6, 61029 Urbino, Pesaro and Urbino, Italy
| | - Fabiola Fanini
- Department
of Biomolecular Sciences, University of
Urbino Carlo Bo, Piazza del Rinascimento 6, 61029 Urbino, Pesaro and Urbino, Italy
| | - Daniele Paderni
- Department
of Pure and Applied Sciences, University
of Urbino Carlo Bo, Via della Stazione 4, 61029 Urbino, Pesaro and Urbino, Italy
| | - Giovanni Piersanti
- Department
of Biomolecular Sciences, University of
Urbino Carlo Bo, Piazza del Rinascimento 6, 61029 Urbino, Pesaro and Urbino, Italy
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7
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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] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [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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Affiliation(s)
- Leanne
M. Riley
- School of Chemistry, The Joseph Black Building, University of Glasgow, Glasgow G12 8QQ, U.K.
| | - Toni N. Mclay
- School of Chemistry, The Joseph Black Building, University of Glasgow, Glasgow G12 8QQ, U.K.
| | - Andrew Sutherland
- School of Chemistry, The Joseph Black Building, University of Glasgow, Glasgow G12 8QQ, U.K.
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8
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Micikas RJ, Acharyya A, Smith AB, Gai F. Synthesis and characterization of the fluorescence utility of two Visible-Light-Absorbing tryptophan derivatives. Chem Phys Lett 2022. [DOI: 10.1016/j.cplett.2022.139553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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9
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Fong KP, Ahmed IA, Mravic M, Jo H, Kim OV, Litvinov RI, Weisel JW, DeGrado WF, Gai F, Bennett JS. Visualization of Platelet Integrins via Two-Photon Microscopy Using Anti-transmembrane Domain Peptides Containing a Blue Fluorescent Amino Acid. Biochemistry 2021; 60:1722-1730. [PMID: 34010565 DOI: 10.1021/acs.biochem.1c00238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The fluorescent reporters commonly used to visualize proteins can perturb both protein structure and function. Recently, we found that 4-cyanotryptophan (4CN-Trp), a blue fluorescent amino acid, is suitable for one-photon imaging applications. Here, we demonstrate its utility in two-photon fluorescence microscopy by using it to image integrins on cell surfaces. Specifically, we used solid-phase peptide synthesis to generate CHAMP peptides labeled with 4-cyanoindole (4CNI) at their N-termini to image integrins on cell surfaces. CHAMP (computed helical anti-membrane protein) peptides spontaneously insert into membrane bilayers to target integrin transmembrane domains and cause integrin activation. We found that 4CNI labeling did not perturb the ability of CHAMP peptides to insert into membranes, bind to integrins, or cause integrin activation. We then used two-photon fluorescence microscopy to image 4CNI-containing integrins on the surface of platelets. Compared to a 4CNI-labeled scrambled peptide that uniformly decorated cell surfaces, 4CNI-labeled CHAMP peptides were present in discrete blue foci. To confirm that these foci represented CN peptide-containing integrins, we co-stained platelets with integrin-specific fluorescent monoclonal antibodies and found that CN peptide and antibody fluorescence coincided. Because 4CNI can readily be biosynthetically incorporated into proteins with little if any effect on protein structure and function, it provides a facile way to directly monitor protein behavior and protein-protein interactions in cellular environments. In addition, these results clearly demonstrate that the two-photon excitation cross section of 4CN-Trp is sufficiently large to make it a useful two-photon fluorescence reporter for biological applications.
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Affiliation(s)
- Karen P Fong
- Hematology-Oncology Division, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Ismail A Ahmed
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Marco Mravic
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, California 94158-2517, United States
| | - Hyunil Jo
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, California 94158-2517, United States
| | - Oleg V Kim
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Rustem I Litvinov
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - John W Weisel
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - William F DeGrado
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, California 94158-2517, United States
| | - Feng Gai
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
| | - Joel S Bennett
- Hematology-Oncology Division, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
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10
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Acharyya A, Zhang W, Gai F. Tryptophan as a Template for Development of Visible Fluorescent Amino Acids. J Phys Chem B 2021; 125:5458-5465. [PMID: 34029101 DOI: 10.1021/acs.jpcb.1c02321] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Most biological systems, at both molecular and cellular levels, are intrinsically complex, diverse, and nonfluorescent. Therefore, studying their structures, dynamics, and interactions via fluorescence-based methods requires incorporation of one or multiple external fluorophores that would not significantly affect any native property of the system in question. This requirement necessitates the development of a diverse set of fluorescence reporters that differ in chemical, physical, and photophysical properties. Herein, we offer our perspective on the need for, recent progress in, and future directions of developing tryptophan-based fluorescent amino acids.
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Affiliation(s)
- Arusha Acharyya
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Wenkai Zhang
- Department of Physics and Applied Optics Beijing Area Major Laboratory, Beijing Normal University, Beijing 100875, China
| | - Feng Gai
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
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11
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Micikas RJ, Ahmed IA, Acharyya A, Smith AB, Gai F. Tuning the electronic transition energy of indole via substitution: application to identify tryptophan-based chromophores that absorb and emit visible light. Phys Chem Chem Phys 2021; 23:6433-6437. [PMID: 33710175 DOI: 10.1039/d0cp06710e] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Fluorescent amino acids (FAAs) offer significant advantages over fluorescent proteins in applications where the fluorophore size needs to be limited or minimized. A long-sought goal in biological spectroscopy/microcopy is to develop visible FAAs by modifying the indole ring of tryptophan. Herein, we examine the absorption spectra of a library of 4-substituted indoles and find that the frequency of the absorption maximum correlates linearly with the global electrophilicity index of the substituent. This finding permits us to identify two promising candidates, 4-formyltryptophan (4CHO-Trp) and 4-nitrotryptophan (4NO2-Trp), both of which can be excited by visible light. Further fluorescence measurements indicate that while 4CHO-indole (and 4CHO-Trp) emits cyan fluorescence with a reasonably large quantum yield (ca. 0.22 in ethanol), 4NO2-indole is essentially non-fluorescent, suggesting that 4CHO-Trp (4NO2-Trp) could be useful as a fluorescence reporter (quencher). In addition, we present a simple method for synthesizing 4CHO-Trp.
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Affiliation(s)
- Robert J Micikas
- Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104, USA.
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12
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Micikas R, Acharyya A, Gai F, Smith AB. A Scalable Synthesis of the Blue Fluorescent Amino Acid 4-Cyanotryptophan and the Fmoc Derivative: Utility Demonstrated with the Influenza M2 Peptide Tetramer. Org Lett 2021; 23:1247-1250. [DOI: 10.1021/acs.orglett.0c04055] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Robert Micikas
- Department of Chemistry, University of Pennsylvania, 231 South 34th St, Philadelphia, Pennsylvania 19104, United States
| | - Arusha Acharyya
- Department of Chemistry, University of Pennsylvania, 231 South 34th St, Philadelphia, Pennsylvania 19104, United States
| | - Feng Gai
- Department of Chemistry, University of Pennsylvania, 231 South 34th St, Philadelphia, Pennsylvania 19104, United States
| | - Amos B. Smith
- Department of Chemistry, University of Pennsylvania, 231 South 34th St, Philadelphia, Pennsylvania 19104, United States
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13
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Boaro A, Ageitos L, Torres M, Bartoloni FH, de la Fuente-Nunez C. Light-Emitting Probes for Labeling Peptides. CELL REPORTS. PHYSICAL SCIENCE 2020; 1:100257. [PMID: 34396352 PMCID: PMC8360326 DOI: 10.1016/j.xcrp.2020.100257] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Peptides are versatile biopolymers composed of 2-100 amino acid residues that present a wide range of biological functions and constitute potential therapies for numerous diseases, partly due to their ability to penetrate cell membranes. However, their mechanisms of action have not been fully elucidated due to the lack of appropriate tools. Existing light-emitting probes are limited by their cytotoxicity and large size, which can alter peptide structure and function. Here, we describe the available fluorescent, bioluminescent, and chemiluminescent probes for labeling peptides, with a focus on minimalistic options.
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Affiliation(s)
- Andreia Boaro
- Machine Biology Group, Departments of Psychiatry and Microbiology, Institute for Biomedical Informatics, Institute for Translational Medicine and Therapeutics, Perelman School of Medicine, and Department of Bioengineering, University of Pennsylvania, 3610 Hamilton Walk, Philadelphia, PA 19104, USA
- Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Avenida dos Estados, 5001, Santo André, São Paulo 09210-580, Brazil
| | - Lucía Ageitos
- Machine Biology Group, Departments of Psychiatry and Microbiology, Institute for Biomedical Informatics, Institute for Translational Medicine and Therapeutics, Perelman School of Medicine, and Department of Bioengineering, University of Pennsylvania, 3610 Hamilton Walk, Philadelphia, PA 19104, USA
- Centro de Investigacións Científicas Avanzadas (CICA) e Departamento de Química, Facultade de Ciencias, Universidade da Coruña, Calle de la Maestranza, 9, A Coruña 15071, Spain
| | - Marcelo Torres
- Machine Biology Group, Departments of Psychiatry and Microbiology, Institute for Biomedical Informatics, Institute for Translational Medicine and Therapeutics, Perelman School of Medicine, and Department of Bioengineering, University of Pennsylvania, 3610 Hamilton Walk, Philadelphia, PA 19104, USA
| | - Fernando Heering Bartoloni
- Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Avenida dos Estados, 5001, Santo André, São Paulo 09210-580, Brazil
| | - Cesar de la Fuente-Nunez
- Machine Biology Group, Departments of Psychiatry and Microbiology, Institute for Biomedical Informatics, Institute for Translational Medicine and Therapeutics, Perelman School of Medicine, and Department of Bioengineering, University of Pennsylvania, 3610 Hamilton Walk, Philadelphia, PA 19104, USA
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14
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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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15
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Liu J, Liu X, Zhang F, Qu J, Sun H, Zhu Q. A Peptide Stapling Strategy with Built‐In Fluorescence by Direct Late‐Stage C(sp
2
)−H Olefination of Tryptophan. Chemistry 2020; 26:16122-16128. [DOI: 10.1002/chem.202003548] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 08/27/2020] [Indexed: 12/31/2022]
Affiliation(s)
- Jiang Liu
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province College of Biotechnology and Bioengineering Zhejiang University of Technology Hangzhou 310014 P.R. China
| | - Xin Liu
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province College of Biotechnology and Bioengineering Zhejiang University of Technology Hangzhou 310014 P.R. China
| | - Fangfang Zhang
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province College of Biotechnology and Bioengineering Zhejiang University of Technology Hangzhou 310014 P.R. China
| | - Jiaojiao Qu
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province College of Biotechnology and Bioengineering Zhejiang University of Technology Hangzhou 310014 P.R. China
| | - Hongyan Sun
- Department of Chemistry and Center of Super-Diamond and Advanced Films (COSDAF) City University of Hong Kong Hong Kong P.R. China
| | - Qing Zhu
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province College of Biotechnology and Bioengineering Zhejiang University of Technology Hangzhou 310014 P.R. China
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16
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Gupta A, Garreffi BP, Guo M. Facile synthesis of a novel genetically encodable fluorescent α-amino acid emitting greenish blue light. Chem Commun (Camb) 2020; 56:12578-12581. [PMID: 32944728 PMCID: PMC7577945 DOI: 10.1039/d0cc03643a] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
We report the facile synthesis and characterization of a novel fluorescent α-amino acid 4-phenanthracen-9-yl-l-phenylalanine (Phen-AA) (5) that emits greenish blue light in the visible region. This genetically encodable l-α-amino acid has excellent photostability with a 75% quantum yield. It readily gets into human cells, being clearly imaged upon 405 nm laser excitation. The synthetic procedure is resistant to racemization and only involves three simple steps which use mild conditions and generate the Phen-AA in reasonably good yield. It may find broad applications in research, biotechnology, and the pharmaceutical industry.
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Affiliation(s)
- Aakash Gupta
- Department of Chemistry and Biochemistry, UMass Cranberry Health Research Center, University of Massachusetts Dartmouth, 285 Old Westport Road, North Dartmouth, MA 02747, USA.
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17
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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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Abstract
Most biological molecules are intrinsically non- or weakly-fluorescent, hence requiring labeling with an external fluorophore(s) to be studied via fluorescence-based techniques. However, such labeling could perturb the native property of the system in question. One effective strategy to minimize such undesirable perturbation is to use fluorophores that are simple analogs of natural amino acids. In this chapter, we describe the synthesis and spectroscopic utility of two indole-based fluorophores, 4-cynaotryprophan (4CN-Trp) and 4-cyanoindole-2'-deoxyribonucleoside (4CNI-NS), with a focus on 4CN-Trp. This unnatural amino acid, which is only slightly larger than its natural counterpart, tryptophan (Trp), exhibits unique photophysical properties, making it a versatile fluorophore in biological spectroscopic and imaging applications. Through several specific examples, we highlight its broad utility in the study of various biological problems and processes.
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Wörner S, Rönicke F, Ulrich AS, Wagenknecht H. 4-Aminophthalimide Amino Acids as Small and Environment-Sensitive Fluorescent Probes for Transmembrane Peptides. Chembiochem 2020; 21:618-622. [PMID: 31432615 PMCID: PMC7079057 DOI: 10.1002/cbic.201900520] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Indexed: 12/15/2022]
Abstract
Fluorescence probing of transmembrane (TM) peptides is needed to complement state-of-the art methods-mainly oriented circular dichroism and solid-state NMR spectroscopy-and to allow imaging in living cells. Three new amino acids incorporating the solvatofluorescent 4-aminophthalimide in their side chains were synthesized in order to examine the local polarity in the α-helical TM fragment of the human epidermal growth factor receptor. It was possible to distinguish their locations, either in the hydrophobic core of the lipid bilayer or at the membrane surface, by fluorescence readout, including blue shift and increased quantum yield. An important feature is the small size of the 4-aminophthalimide chromophore. It makes one of the new amino acids approximately isosteric to tryptophan, typically used as a very small fluorescent amino acid in peptides and proteins. In contrast to the only weakly fluorescent indole system in tryptophan, the 4-aminophthalimide moiety produces a significantly more informative fluorescence readout and is selectively excited outside the biopolymer absorption range.
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Affiliation(s)
- Samantha Wörner
- Karlsruhe Institute of Technology (KIT)Institute of Organic ChemistryFritz-Haber-Weg 676131KarlsruheGermany
| | - Franziska Rönicke
- Karlsruhe Institute of Technology (KIT)Institute of Organic ChemistryFritz-Haber-Weg 676131KarlsruheGermany
| | - Anne S. Ulrich
- Karlsruhe Institute of Technology (KIT)IBG-2 and Institute of Organic ChemistryFritz-Haber-Weg 676131KarlsruheGermany
| | - Hans‐Achim Wagenknecht
- Karlsruhe Institute of Technology (KIT)Institute of Organic ChemistryFritz-Haber-Weg 676131KarlsruheGermany
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Ahmed IA, Rodgers JM, Eng C, Troxler T, Gai F. PET and FRET utility of an amino acid pair: tryptophan and 4-cyanotryptophan. Phys Chem Chem Phys 2019; 21:12843-12849. [PMID: 31179453 PMCID: PMC6587589 DOI: 10.1039/c9cp02126d] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Methods based on fluorescence resonance energy transfer (FRET) and photo-induced electron transfer (PET) are widely used in the biological sciences, employing mostly dye-based FRET and PET pairs. While very useful and important, dye-based reporters are not always applicable without concern, for example, in cases where the fluorophore size needs to be minimized. Therefore, development and characterization of smaller, ideally amino acid-based PET and FRET pairs will expand the biological spectroscopy toolbox to enable new applications. Herein, we show that, depending on the excitation wavelength, tryptophan and 4-cyanotrptophan can interact with each other via the mechanism of either energy or electron transfer, hence constituting a dual FRET and PET pair. The biological utility of this amino acid pair is further demonstrated by applying it to study the end-to-end collision rate of a short peptide, the mode of interaction between a ligand and BSA, and the activity of a protease.
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Affiliation(s)
- Ismail A. Ahmed
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Jeffrey M. Rodgers
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Christina Eng
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Thomas Troxler
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Feng Gai
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
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