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Wang J, Liu Y. Systematic Theoretical Study on the pH-Dependent Absorption and Fluorescence Spectra of Flavins. Molecules 2023; 28:molecules28083315. [PMID: 37110549 PMCID: PMC10146991 DOI: 10.3390/molecules28083315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 03/29/2023] [Accepted: 04/07/2023] [Indexed: 04/29/2023] Open
Abstract
Flavins are a class of organic compounds with the basic structure of 7,8-dimethy-10-alkyl isoalloxazine. They are ubiquitous in nature and participate in many biochemical reactions. Due to various existing forms, there is a lack of systematic research on the absorption and fluorescence spectra of flavins. In this study, employing the density functional theory (DFT) and time-dependent (TD) DFT, we calculated the pH-dependent absorption and fluorescence spectra of flavin of three redox states (quinone, semiquinone, and hydroquinone) in solvents. The chemical equilibrium of three redox states of flavins and the pH effect on the absorption spectra and fluorescence spectra of flavins were carefully discussed. The conclusion helps with identifying the existing forms of flavins in solvent with different pH values.
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Affiliation(s)
- Jinyu Wang
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Yajun Liu
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
- Center for Advanced Materials Research, Beijing Normal University, Zhuhai 519087, China
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2
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Vinod Mouli MSS, Kumar Mishra A. Divergent Crystallographic Architecture for Silver‐Flavin Complexes Induced via pH Variation. ChemistrySelect 2022. [DOI: 10.1002/slct.202202126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- M. S. S. Vinod Mouli
- Department of Chemistry Indian Institute of Technology Hyderabad Kandi Sangareddy 502285 Telangana
| | - Ashutosh Kumar Mishra
- Department of Chemistry Indian Institute of Technology Hyderabad Kandi Sangareddy 502285 Telangana
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3
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Wang J, Liu Y. Vibrationally resolved absorption and fluorescence spectra of flavins: A theoretical simulation in the gas phase. J CHIN CHEM SOC-TAIP 2022. [DOI: 10.1002/jccs.202200243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Jinyu Wang
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry Beijing Normal University Beijing China
| | - Ya‐Jun Liu
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry Beijing Normal University Beijing China
- Center for Advanced Materials Research Beijing Normal University Zhuhai China
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4
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Pérez-Herráez I, Justo-Tirado M, Bueno-Cuenca M, Zaballos-García E, Pérez-Prieto J. Flavin adenine dinucleotide-capped gold nanoclusters: biocompatible photo-emissive nanomaterial and reservoir of lumichrome. NANOSCALE ADVANCES 2022; 4:2250-2254. [PMID: 36133697 PMCID: PMC9418107 DOI: 10.1039/d2na00110a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Accepted: 04/14/2022] [Indexed: 06/16/2023]
Abstract
A novel biocompatible nanohybrid consisting of gold nanoclusters (AuNCs) capped with FAD cofactor molecules exhibits distinctive and unique features compared to those of free FAD. The spherical shape of the AuNC provides a large surface to volume ratio, thereby enabling a huge amount of FAD on the AuNC surface while, in basic media and under nitrogen atmosphere, the considerable curvature of its surface enables light-triggered delivery of lumichrome, which is an effective photosensitizer and fluorescent probe.
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Affiliation(s)
- Irene Pérez-Herráez
- Instituto de Ciencia Molecular (ICMol), Universitat de Valencia Calle Catedrático José Beltrán 2 46980 Paterna Valencia Spain
- Department of Organic Chemistry, Universitat de Valencia Av. Vicent Andrés Estellés s/n 46100 Burjassot Valencia Spain
| | - Miguel Justo-Tirado
- Instituto de Ciencia Molecular (ICMol), Universitat de Valencia Calle Catedrático José Beltrán 2 46980 Paterna Valencia Spain
- Department of Organic Chemistry, Universitat de Valencia Av. Vicent Andrés Estellés s/n 46100 Burjassot Valencia Spain
| | - Mar Bueno-Cuenca
- Department of Organic Chemistry, Universitat de Valencia Av. Vicent Andrés Estellés s/n 46100 Burjassot Valencia Spain
| | - Elena Zaballos-García
- Department of Organic Chemistry, Universitat de Valencia Av. Vicent Andrés Estellés s/n 46100 Burjassot Valencia Spain
| | - Julia Pérez-Prieto
- Instituto de Ciencia Molecular (ICMol), Universitat de Valencia Calle Catedrático José Beltrán 2 46980 Paterna Valencia Spain
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5
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Müller D, Dopfer O. Optical spectroscopy of cryogenic metalated flavins: The O2(+) isomers of M+lumiflavin (M=Li–Cs). JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY 2020. [DOI: 10.1016/j.jpap.2020.100009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
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6
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Tasnim H, Landry AP, Fontenot CR, Ding H. Exploring the FMN binding site in the mitochondrial outer membrane protein mitoNEET. Free Radic Biol Med 2020; 156:11-19. [PMID: 32445867 PMCID: PMC7434653 DOI: 10.1016/j.freeradbiomed.2020.05.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 05/06/2020] [Accepted: 05/06/2020] [Indexed: 12/17/2022]
Abstract
MitoNEET is a mitochondrial outer membrane protein that hosts a redox active [2Fe-2S] cluster in the C-terminal cytosolic domain. Increasing evidence has shown that mitoNEET has an essential role in regulating energy metabolism in human cells. Previously, we reported that the [2Fe-2S] clusters in mitoNEET can be reduced by the reduced flavin mononucleotide (FMNH2) and oxidized by oxygen or ubiquinone-2, suggesting that mitoNEET may act as a novel redox enzyme catalyzing electron transfer from FMNH2 to oxygen or ubiquinone. Here, we explore the FMN binding site in mitoNEET by using FMN analogs and find that lumiflavin, like FMN, at nanomolar concentrations can mediate the redox transition of the mitoNEET [2Fe-2S] clusters in the presence of flavin reductase and NADH (100 μM) under aerobic conditions. The electron paramagnetic resonance (EPR) measurements show that both FMN and lumiflavin can dramatically change the EPR spectrum of the reduced mitoNEET [2Fe-2S] clusters and form a covalently bound complex with mitoNEET under blue light exposure, suggesting that FMN/lumiflavin has specific interactions with the [2Fe-2S] clusters in mitoNEET. In contrast, lumichrome, another FMN analog, fails to mediate the redox transition of the mitoNEET [2Fe-2S] clusters and has no effect on the EPR spectrum of the reduced mitoNEET [2Fe-2S] clusters under blue light exposure. Instead, lumichrome can effectively inhibit the FMNH2-mediated reduction of the mitoNEET [2Fe-2S] clusters, indicating that lumichrome may act as a potential inhibitor to block the electron transfer activity of mitoNEET.
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Affiliation(s)
- Homyra Tasnim
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, 70803, USA
| | - Aaron P Landry
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, 70803, USA
| | - Chelsey R Fontenot
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, 70803, USA
| | - Huangen Ding
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, 70803, USA.
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7
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Mondal P, Schwinn K, Huix-Rotllant M. Impact of the redox state of flavin chromophores on the UV–vis spectra, redox and acidity constants and electron affinities. J Photochem Photobiol A Chem 2020. [DOI: 10.1016/j.jphotochem.2019.112164] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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8
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Müller D, Dopfer O. Vibronic optical spectroscopy of cryogenic flavin ions: the O2+ and N1 tautomers of protonated lumiflavin. Phys Chem Chem Phys 2020; 22:18328-18339. [DOI: 10.1039/d0cp03650a] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The electronic structure of cryogenic protonated lumiflavin ions probed by photodissociation spectroscopy and density functional theory calculations reveals the presence of the two most stable tautomers protonated at the O2+ and N1 positions.
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Affiliation(s)
- David Müller
- Institut für Optik und Atomare Physik
- Technische Universität Berlin
- D-10623 Berlin
- Germany
| | - Otto Dopfer
- Institut für Optik und Atomare Physik
- Technische Universität Berlin
- D-10623 Berlin
- Germany
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9
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Youn UJ, Lee JH, Han SJ. Diketopiperazine and alloxazine alkaloids from the antarctic bacteria, Pseudorhodobacter psychrotolerans sp. nov. BIOCHEM SYST ECOL 2019. [DOI: 10.1016/j.bse.2019.04.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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10
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Müller D, Nieto P, Miyazaki M, Dopfer O. Effect of alkali ions on optical properties of flavins: vibronic spectra of cryogenic M+lumiflavin complexes (M = Li–Cs). Faraday Discuss 2019; 217:256-275. [DOI: 10.1039/c8fd00203g] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Cryogenic ion spectroscopy of metal–lumiflavin (M+LF) complexes at the level of vibrational resolution illustrates the large impact of alkali ions on the optical properties of this prototypical flavin molecule.
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Affiliation(s)
- David Müller
- Institut für Optik und Atomare Physik
- Technische Universität Berlin
- 10623 Berlin
- Germany
| | - Pablo Nieto
- Institut für Optik und Atomare Physik
- Technische Universität Berlin
- 10623 Berlin
- Germany
| | - Mitsuhiko Miyazaki
- Institut für Optik und Atomare Physik
- Technische Universität Berlin
- 10623 Berlin
- Germany
- Laboratory for Chemistry and Life Science
| | - Otto Dopfer
- Institut für Optik und Atomare Physik
- Technische Universität Berlin
- 10623 Berlin
- Germany
- Tokyo Tech World Research Hub Initiative (WRHI)
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11
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Ahmad I, Mirza T, Musharraf SG, Anwar Z, Sheraz MA, Ahmed S, Ejaz MA, Khurshid A. Photolysis of carboxymethylflavin in aqueous and organic solvent: a kinetic study. RSC Adv 2019; 9:26559-26571. [PMID: 35528592 PMCID: PMC9070421 DOI: 10.1039/c9ra02818h] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2019] [Accepted: 07/24/2019] [Indexed: 12/04/2022] Open
Abstract
This is the first study on the photolysis of carboxymethylflavin (CMF), an intermediate in the photolysis of riboflavin (RF). CMF is photodegraded by removal of side-chain to lumichrome (LC) in acid solution and to LC and lumiflavin (LF) in alkaline solution. It also undergoes alkaline hydrolysis to 1,2-dihydro-1-methyl-2-keto-3-quinoxaline carboxylic acid (KA) and 1,2,3,4-tetrahydro-1-methyl-2,3-dioxoquinoxaline (DQ) by cleavage of isoalloxazine ring. CMF degrades to LC in organic solvents. The formation of LC in acid solution and organic solvents takes place by second-order reaction and those of LC, LF, KA and DQ in alkaline solution by first-order reactions. The values of second-order rate constants for the photolysis of CMF at pH 2.0 to 7.0 are in the range of 1.13 to 2.45 M−1 s−1 and those of first-order rate constants (kobs) at pH 8.0–12.0 from 1.53 to 4.18 × 10−4 s−1 and for the formation of photoproducts from 0.37 to 16.6 × 10−5 s−1. The photolysis of CMF is enhanced, with pH, in the alkaline region since the excited state is sensitive to alkaline hydrolysis. The photolysis and fluorescence quantum yields of CMF in aqueous and organic solvents have been reported. CMF and photoproducts have been assayed spectrofluorimetrically. The mode of CMF photolysis is discussed. Carboxymethylflavin (CMF) undergoes photolysis in acid solution to form lumichrome (LC) and in alkaline solution, LC and lumiflavin (LF) by side-chain cleavage and β-keto acid and a dioxoquinoxalaine (DQ) compound by isoalloxazine ring cleavage.![]()
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Affiliation(s)
- Iqbal Ahmad
- Baqai Institute of Pharmaceutical Sciences
- Baqai Medical University
- Karachi
- Pakistan
| | - Tania Mirza
- Baqai Institute of Pharmaceutical Sciences
- Baqai Medical University
- Karachi
- Pakistan
| | | | - Zubair Anwar
- Baqai Institute of Pharmaceutical Sciences
- Baqai Medical University
- Karachi
- Pakistan
| | - Muhammad Ali Sheraz
- Baqai Institute of Pharmaceutical Sciences
- Baqai Medical University
- Karachi
- Pakistan
| | - Sofia Ahmed
- Baqai Institute of Pharmaceutical Sciences
- Baqai Medical University
- Karachi
- Pakistan
| | - Muhammad Ahsan Ejaz
- Baqai Institute of Pharmaceutical Sciences
- Baqai Medical University
- Karachi
- Pakistan
| | - Adeela Khurshid
- Baqai Institute of Pharmaceutical Sciences
- Baqai Medical University
- Karachi
- Pakistan
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12
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Matthews E, Cercola R, Dessent CEH. Protomer-Dependent Electronic Spectroscopy and Photochemistry of the Model Flavin Chromophore Alloxazine. Molecules 2018; 23:molecules23082036. [PMID: 30110962 PMCID: PMC6222404 DOI: 10.3390/molecules23082036] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Revised: 08/10/2018] [Accepted: 08/11/2018] [Indexed: 12/16/2022] Open
Abstract
Flavin chromophores play key roles in a wide range of photoactive proteins, but key questions exist in relation to their fundamental spectroscopic and photochemical properties. In this work, we report the first gas-phase spectroscopy study of protonated alloxazine (AL∙H⁺), a model flavin chromophore. Laser photodissociation is employed across a wide range (2.34⁻5.64 eV) to obtain the electronic spectrum and characterize the photofragmentation pathways. By comparison to TDDFT quantum chemical calculations, the spectrum is assigned to two AL∙H⁺ protomers; an N5 (dominant) and O4 (minor) form. The protomers have distinctly different spectral profiles in the region above 4.8 eV due to the presence of a strong electronic transition for the O4 protomer corresponding to an electron-density shift from the benzene to uracil moiety. AL∙H⁺ photoexcitation leads to fragmentation via loss of HCN and HNCO (along with small molecules such as CO₂ and H₂O), but the photofragmentation patterns differ dramatically from those observed upon collision excitation of the ground electronic state. This reveals that fragmentation is occurring during the excited state lifetime. Finally, our results show that the N5 protomer is associated primarily with HNCO loss while the O4 protomer is associated with HCN loss, indicating that the ring-opening dynamics are dependent on the location of protonation in the ground-state molecule.
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Affiliation(s)
- Edward Matthews
- Department of Chemistry, University of York, Heslington, York YO10 5DD, UK.
| | - Rosaria Cercola
- Department of Chemistry, University of York, Heslington, York YO10 5DD, UK.
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13
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Nieto P, Müller D, Sheldrick A, Günther A, Miyazaki M, Dopfer O. Effect of alkali ions on optical properties of flavins: vibronic spectra of cryogenic M+lumichrome ions (M = Li–Cs) in the gas phase. Phys Chem Chem Phys 2018; 20:22148-22158. [DOI: 10.1039/c8cp03950j] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Cryogenic ion spectroscopy of M+LC (M = Li–Cs) obtained by photodissociation of mass selected ions in a tandem mass spectrometer illustrates the large impact of metalation on the optical properties of the simplest flavin molecule.
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Affiliation(s)
- Pablo Nieto
- Institut für Optik und Atomare Physik
- Technische Universität Berlin
- Berlin D-10623
- Germany
| | - David Müller
- Institut für Optik und Atomare Physik
- Technische Universität Berlin
- Berlin D-10623
- Germany
| | - Alexander Sheldrick
- Institut für Optik und Atomare Physik
- Technische Universität Berlin
- Berlin D-10623
- Germany
| | - Alan Günther
- Institut für Optik und Atomare Physik
- Technische Universität Berlin
- Berlin D-10623
- Germany
| | - Mitsuhiko Miyazaki
- Institut für Optik und Atomare Physik
- Technische Universität Berlin
- Berlin D-10623
- Germany
- Laboratory for Chemistry and Life Science
| | - Otto Dopfer
- Institut für Optik und Atomare Physik
- Technische Universität Berlin
- Berlin D-10623
- Germany
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14
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Galbán J, Sanz-Vicente I, Navarro J, de Marcos S. The intrinsic fluorescence of FAD and its application in analytical chemistry: a review. Methods Appl Fluoresc 2016; 4:042005. [DOI: 10.1088/2050-6120/4/4/042005] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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15
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Prukala D, Khmelinskii I, Koput J, Gierszewski M, Pędziński T, Sikorski M. Photophysics, excited-state double-proton transfer and hydrogen-bonding properties of 5-deazaalloxazines. Photochem Photobiol 2014; 90:972-88. [PMID: 24816028 DOI: 10.1111/php.12289] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Accepted: 05/06/2014] [Indexed: 11/30/2022]
Abstract
The photophysical properties of 5-deazaalloxazine and 1,3-dimethyl-5-deazaalloxazine were studied in different solvents. These compounds have higher values of fluorescence quantum yields and longer fluorescence lifetimes, compared to those obtained for their alloxazine analogs. Electronic structure and S0 -Si transitions were investigated using the ab initio methods [MP2, CIS(D), EOM-CCSD] with the correlation-consistent basis sets. Also the time-dependent density functional theory (TD-DFT) has been employed. The lowest singlet excited states of 5-deazaalloxazine and 1,3-dimethyl-5-deazaalloxazine are predicted to have the π, π* character, whereas similar alloxazines have two close-lying π, π* and n, π* transitions. Experimental steady-state and time-resolved spectral studies indicate formation of an isoalloxazinic excited state via excited-state double-proton transfer (ESDPT) catalyzed by an acetic acid molecule that forms a hydrogen bond complex with the 5-deazaalloxazine molecule. Solvatochromism of both 5-deazaalloxazine and its 1,3-dimethyl substituted derivative was analyzed using the Kamlet-Taft scale and four-parameter Catalán solvent scale. The most significant result of our studies is that the both scales show a strong influence of solvent acidity (hydrogen bond donating ability) on the emission properties of these compounds, indicating the importance of intermolecular solute-solvent hydrogen-bonding interactions in their excited state.
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Affiliation(s)
- Dorota Prukala
- Faculty of Chemistry, Adam Mickiewicz University in Poznań, Poznań, Poland
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16
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Zhao J, Zaino LP, Bohna PW. Potential-dependent single molecule blinking dynamics for flavin adenine dinucleotide covalently immobilized in zero-mode waveguide array of working electrodes. Faraday Discuss 2014; 164:57-69. [PMID: 24466658 DOI: 10.1039/c3fd00013c] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Single molecules exhibit a set of behaviors that are characteristic and distinct from larger ensembles. Blinking is one such behavior that involves episodic transitions between luminescent and dark states. In addition to the common blinking mechanisms, flavin adenine dinucleotide (FAD), a cofactor in many common redox enzymes, exhibits blinking by cycling between a highly fluorescent oxidized state and a dark reduced state. In contrast to its behavior in flavoenzymes, where the transitions are coupled to chemical redox events, here we study single FAD molecules that are chemically immobilized to the Au region of a zero-mode waveguide (ZMW) array through a pyrroloquinoline quinone (PQQ) linker. In this structure, the Au functions both to confine the optical field in the ZMW and as the working electrode in a potentiostatically controlled 3-elecrode system, thus allowing potential-dependent blinking to be studied in single FAD molecules. The subset of ZMW nanopores housing a single molecule were identified statistically, and these were subjected to detailed study. Using equilibrium potential, E(eq), values determined from macroscopic planar Au electrodes, single molecule blinking behavior was characterized at potentials E < E(eq), E - E(eq), and E > E(eq). The probability of observing a reduced (oxidized) state is observed to increase (decrease) as the potential is scanned cathodic of E(eq). This is understood to reflect the potential-dependent probability of electron transfer for single FAD molecules. Furthermore, the observed transition rate reaches a maximum near E(eq) and decreases to either anodic or cathodic values, as expected, since the rate is dependent on having significant probabilities for both redox states, a condition that is obtained only near E(eq).
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Affiliation(s)
- Jing Zhao
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Lawrence P Zaino
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Paul W Bohna
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, IN 46556, USA
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17
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Prukała D, Gierszewski M, Pędziński T, Sikorski M. Influence of pH on spectral and photophysical properties of 9-methyl-5-deazaalloxazine and 10-ethyl-5-deaza-isoalloxazine. J Photochem Photobiol A Chem 2014. [DOI: 10.1016/j.jphotochem.2013.10.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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18
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19
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Penzkofer A. Reduction-oxidation photocycle dynamics of flavins in starch films. Int J Mol Sci 2012; 13:9157-9183. [PMID: 22942758 PMCID: PMC3430289 DOI: 10.3390/ijms13079157] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2012] [Revised: 07/02/2012] [Accepted: 07/11/2012] [Indexed: 01/30/2023] Open
Abstract
The blue-light photo-reduction (conversion of oxidized flavin quinone via flavin semiquinone to fully reduced flavin hydroquinone) and dark re-oxidation of the flavins riboflavin and lumiflavin in starch (α-amylose) films was studied by absorption and luminescence spectroscopy. Blue-light photo-excitation caused an absorption, fluorescence, and phosphorescence decrease which recovered in the dark. The photo-reduction dark-oxidation cycle could be repeated. The efficiency of photo-reduction decreased with exposed excitation energy, and the speed of re-oxidation in the dark slowed down with time after excitation. The absorption did not fully recover. The fluorescence efficiency after a long time of storage in the dark increased beyond the initial flavin quinone fluorescence efficiency. Flavin photo-excitation is thought to cause starch-flavin restructuring (static fluorescence quenching center formation), enabling enhanced photo-induced starch to flavin electron transfer with subsequent flavin reduction and starch oxidation. In the dark, after light switch-off, thermal reversion of flavin reduction and starch oxidation occurred.
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Affiliation(s)
- Alfons Penzkofer
- Faculty of Physics, University of Regensburg, Universitaetsstrasse 31, D-93053 Regensburg, Germany
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20
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Penzkofer A. Photoluminescence behavior of riboflavin and lumiflavin in liquid solutions and solid films. Chem Phys 2012. [DOI: 10.1016/j.chemphys.2012.03.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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21
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Li H, Melø T, Razi Naqvi K. Triplets, radical cations and neutral semiquinone radicals of lumiflavin and riboflavin: An overhaul of previous pump–probe data and new multichannel absolute absorption spectra. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2012; 106:34-9. [DOI: 10.1016/j.jphotobiol.2011.10.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2011] [Revised: 08/04/2011] [Accepted: 10/04/2011] [Indexed: 10/16/2022]
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22
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Penzkofer A, Stierl M, Hegemann P, Kateriya S. Photo-dynamics of the BLUF domain containing soluble adenylate cyclase (nPAC) from the amoeboflagellate Naegleria gruberi NEG-M strain. Chem Phys 2011. [DOI: 10.1016/j.chemphys.2011.05.028] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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23
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Espy R, Pelton E, Opseth A, Kasprisin J, Nienow AM. Photodegradation of the herbicide imazethapyr in aqueous solution: effects of wavelength, pH, and natural organic matter (NOM) and analysis of photoproducts. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2011; 59:7277-7285. [PMID: 21639113 DOI: 10.1021/jf200573g] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The photodegradation of imazethapyr, 5-ethyl-2-(4-isopropyl-4-methyl-5-oxo-4,5-dihydroimidazol-1H-3-yl)nicotinic acid, has been investigated in phosphate buffers and in buffered solutions containing natural organic matter (NOM). Imazethapyr degrades most quickly under 253.7 nm light and at pH values >4. The presence of NOM in solution caused the reaction rate constants for the photodegradation to decrease, with higher concentrations of NOM having a larger effect. Calculations suggest light screening is the major effect of the NOM. Seven photoproducts have been identified, and a photodegradation mechanism is proposed.
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Affiliation(s)
- Ryan Espy
- Gustavus Adolphus College, MN 56082, USA
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Gärtner W, Hegemann P. Introduction to the Symposium-in Print: Blue light effects. Photochem Photobiol 2011; 87:489-90. [DOI: 10.1111/j.1751-1097.2011.00926.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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van Stokkum IHM, Gauden M, Crosson S, van Grondelle R, Moffat K, Kennis JTM. The primary photophysics of the Avena sativa phototropin 1 LOV2 domain observed with time-resolved emission spectroscopy. Photochem Photobiol 2011; 87:534-41. [PMID: 21261629 DOI: 10.1111/j.1751-1097.2011.00903.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The phototropins are blue-light receptors that base their light-dependent action on the reversible formation of a covalent bond between a flavin mononucleotide (FMN) cofactor and a conserved cysteine in light, oxygen or voltage (LOV) domains. The primary reactions of the Avena sativa phototropin 1 LOV2 domain were investigated by means of time-resolved and low-temperature fluorescence spectroscopy. Synchroscan streak camera experiments revealed a fluorescence lifetime of 2.2 ns in LOV2. A weak long-lived component with emission intensity from 600 to 650 nm was assigned to phosphorescence from the reactive FMN triplet state. This observation allowed determination of the LOV2 triplet state energy level at physiological temperature at 16600 cm(-1). FMN dissolved in aqueous solution showed pH-dependent fluorescence lifetimes of 2.7 ns at pH 2 and 3.9-4.1 ns at pH 3-8. Here, too, a weak phosphorescence band was observed. The fluorescence quantum yield of LOV2 increased from 0.13 to 0.41 upon cooling the sample from 293 to 77 K. A pronounced phosphorescence emission around 600 nm was observed in the LOV2 domain between 77 and 120 K in the steady-state emission.
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Affiliation(s)
- Ivo H M van Stokkum
- Department of Physics and Astronomy, Faculty of Sciences, VU University, Amsterdam, The Netherlands
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Tyagi A, Penzkofer A. Absorption and Emission Spectroscopic Characterization of Lumichrome in Aqueous Solutions†. Photochem Photobiol 2010; 87:524-33. [DOI: 10.1111/j.1751-1097.2010.00836.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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