1
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Gao X, Huo H, Bao H, Wang J, Gao D. Changes of Active Substances in Ganoderma lucidum during Different Growth Periods and Analysis of Their Molecular Mechanism. Molecules 2024; 29:2591. [PMID: 38893471 PMCID: PMC11173900 DOI: 10.3390/molecules29112591] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2024] [Revised: 05/18/2024] [Accepted: 05/28/2024] [Indexed: 06/21/2024] Open
Abstract
Ganoderma lucidum, renowned as an essential edible and medicinal mushroom in China, remains shrouded in limited understanding concerning the intrinsic mechanisms governing the accumulation of active components and potential protein expression across its diverse developmental stages. Accordingly, this study employed a meticulous integration of metabolomics and proteomics techniques to scrutinize the dynamic alterations in metabolite accumulation and protein expression in G. lucidum throughout its growth phases. The metabolomics analysis unveiled elevated levels of triterpenoids, steroids, and polyphenolic compounds during the budding stage (BS) of mushroom growth, with prominent compounds including Diplazium and Ganoderenic acids E, H, and I, alongside key steroids such as cholesterol and 4,4-dimethyl-5alpha-cholesta-8,14,24-trien-3beta-ol. Additionally, nutrients such as polysaccharides, flavonoids, and purines exhibited heightened presence during the maturation stage (FS) of ascospores. Proteomic scrutiny demonstrated the modulation of triterpenoid synthesis by the CYP450, HMGR, HMGS, and ERG protein families, all exhibiting a decline as G. lucidum progressed, except for the ARE family, which displayed an upward trajectory. Therefore, BS is recommended as the best harvesting period for G. lucidum. This investigation contributes novel insights into the holistic exploitation of G. lucidum.
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Affiliation(s)
- Xusheng Gao
- Key Laboratory of Edible Fungi Resources and Utilization, College of Traditional Chinese Medicine, Ministry of Agriculture and Rural Affairs, Jilin Agricultural University, Changchun 130118, China; (X.G.); (H.H.)
| | - Huimin Huo
- Key Laboratory of Edible Fungi Resources and Utilization, College of Traditional Chinese Medicine, Ministry of Agriculture and Rural Affairs, Jilin Agricultural University, Changchun 130118, China; (X.G.); (H.H.)
| | - Haiying Bao
- Key Laboratory of Edible Fungi Resources and Utilization, College of Traditional Chinese Medicine, Ministry of Agriculture and Rural Affairs, Jilin Agricultural University, Changchun 130118, China; (X.G.); (H.H.)
| | - Jialu Wang
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing 100700, China;
| | - Dan Gao
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing 100700, China;
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2
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Panter S, Ayekoi A, Tesche J, Chen J, Illarionov B, Bacher A, Fischer M, Weber S. Shining a Spotlight on Methyl Groups: Photochemically Induced Dynamic Nuclear Polarization Spectroscopy of 5-Deazariboflavin and Its Nor Analogs. Int J Mol Sci 2024; 25:848. [PMID: 38255921 PMCID: PMC10815406 DOI: 10.3390/ijms25020848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Revised: 01/07/2024] [Accepted: 01/08/2024] [Indexed: 01/24/2024] Open
Abstract
5-Deazaflavins are analogs of naturally occurring flavin cofactors. They serve as substitutes for natural flavin cofactors to investigate and modify the reaction pathways of flavoproteins. Demethylated 5-deazaflavins are potential candidates for artificial cofactors, allowing us to fine-tune the reaction kinetics and absorption characteristics of flavoproteins. In this contribution, demethylated 5-deazariboflavin radicals are investigated (1) to assess the influence of the methyl groups on the electronic structure of the 5-deazaflavin radical and (2) to explore their photophysical properties with regard to their potential as artificial cofactors. We determined the proton hyperfine structure of demethylated 5-deazariboflavins using photochemically induced dynamic nuclear polarization (photo-CIDNP) spectroscopy, as well as density functional theory (DFT). To provide context, we compare our findings to a study of flavin mononucleotide (FMN) derivatives. We found a significant influence of the methylation pattern on the absorption properties, as well as on the proton hyperfine coupling ratios of the xylene moiety, which appears to be solvent-dependent. This effect is enhanced by the replacement of N5 by C5-H in 5-deazaflavin derivatives compared to their respective flavin counterparts.
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Affiliation(s)
- Sabrina Panter
- Institut für Physikalische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104 Freiburg, Germany; (S.P.); (A.A.)
| | - Audrey Ayekoi
- Institut für Physikalische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104 Freiburg, Germany; (S.P.); (A.A.)
| | - Jannis Tesche
- Institut für Physikalische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104 Freiburg, Germany; (S.P.); (A.A.)
| | - Jing Chen
- Institut für Physikalische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104 Freiburg, Germany; (S.P.); (A.A.)
| | - Boris Illarionov
- Institut für Lebensmittelchemie, Universität Hamburg, Grindelallee 117, 20146 Hamburg, Germany; (B.I.); (M.F.)
| | - Adelbert Bacher
- TUM School of Natural Sciences, Technische Universität München, Lichtenbergstr. 4, 85747 Garching, Germany;
| | - Markus Fischer
- Institut für Lebensmittelchemie, Universität Hamburg, Grindelallee 117, 20146 Hamburg, Germany; (B.I.); (M.F.)
| | - Stefan Weber
- Institut für Physikalische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104 Freiburg, Germany; (S.P.); (A.A.)
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3
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Wörner J, Panter S, Illarionov B, Bacher A, Fischer M, Weber S. Expanding Reaction Horizons: Evidence of the 5-Deazaflavin Radical Through Photochemically Induced Dynamic Nuclear Polarization. Angew Chem Int Ed Engl 2023; 62:e202309334. [PMID: 37571931 DOI: 10.1002/anie.202309334] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 08/09/2023] [Accepted: 08/10/2023] [Indexed: 08/13/2023]
Abstract
Deazaflavins are important analogues of the naturally occurring flavins: riboflavin, flavin mononucleotide (FMN), and flavin adenine dinucleotide (FAD). The use of 5-deazaflavin as a replacement coenzyme in a number of flavoproteins has proven particularly valuable in unraveling and manipulating their reaction mechanisms. It was frequently reported that one-electron-transfer reactions in flavoproteins are impeded with 5-deazaflavin as the cofactor. Based on these findings, it was concluded that the 5-deazaflavin radical is significantly less stable compared to the respective flavin semiquinone and quickly re-oxidizes or undergoes disproportionation. The long-standing paradigm of 5-deazaflavin being solely a two-electron/hydride acceptor/donor-"a nicotinamide in flavin clothing"-needs to be re-evaluated now with the indirect observation of a one-electron-reduced (paramagnetic) species using photochemically induced dynamic nuclear polarization (photo-CIDNP) 1 H nuclear magnetic resonance (NMR) under biologically relevant conditions.
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Affiliation(s)
- Jakob Wörner
- Institut für Physikalische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstraße 21, 79104, Freiburg, Germany
| | - Sabrina Panter
- Institut für Physikalische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstraße 21, 79104, Freiburg, Germany
| | - Boris Illarionov
- Institut für Lebensmittelchemie, Universität Hamburg, Grindelallee 117, 20146, Hamburg, Germany
| | - Adelbert Bacher
- TUM School of Natural Sciences, Technische Universität München, Lichtenbergstraße 4, 85747, Garching, Germany
| | - Markus Fischer
- Institut für Lebensmittelchemie, Universität Hamburg, Grindelallee 117, 20146, Hamburg, Germany
| | - Stefan Weber
- Institut für Physikalische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstraße 21, 79104, Freiburg, Germany
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4
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Ribes J, Bourdeau Y, Rascol E, Bestel I, Badarau E. Enhancing the photosensitizing activity of natural flavins: Tuning the heavy-atom effect in the isoalloxazine series. Bioorg Med Chem 2023; 81:117210. [PMID: 36791612 DOI: 10.1016/j.bmc.2023.117210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Revised: 02/04/2023] [Accepted: 02/06/2023] [Indexed: 02/12/2023]
Abstract
Structure-photosensitizing activity relationships for a series of flavin analogues were investigated with the final goal of identifying the most potent photosensitizer in these series. The main structural modifications involved the introduction of various halogen atoms in C7- and/or C8-positions on the isoalloxazine ring. These compounds were synthesized by reacting judiciously-functionalized anilines with alloxan. The SAR trends showed that the photosensitizing activity increased with the size of the halogen atoms, confirming the importance of the heavy-atom effect on the photosensitizer's activity. The halogens in C8 were more active than the di-substituted halogens, which in turn were more active than the C7-substituted equivalents. However, even if the photosensitizing activity is slightly less important for the 7- compared to the 8-substituted derivatives, the 7-haloisoalloxazines are promising photosensitizers, as they present a better cellular toxicity profile than the 8-substituted analoges. The photosensitizing activity perfectly correlated with the determined fluorescence for the same compounds. Except for the dihalogeno derivatives, all the compounds were not toxic up to a 50 μM range.
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Affiliation(s)
- Jonathan Ribes
- University of Bordeaux, CNRS, CBMN, UMR 5248, Institute of Chemistry and Biology of Membranes & Nano-objects (CBMN), Allée Geoffroy Saint Hilaire, Bât B14, 33600 Pessac, France
| | - Yann Bourdeau
- University of Bordeaux, CNRS, CBMN, UMR 5248, Institute of Chemistry and Biology of Membranes & Nano-objects (CBMN), Allée Geoffroy Saint Hilaire, Bât B14, 33600 Pessac, France
| | - Estelle Rascol
- University of Bordeaux, CNRS, CBMN, UMR 5248, Institute of Chemistry and Biology of Membranes & Nano-objects (CBMN), Allée Geoffroy Saint Hilaire, Bât B14, 33600 Pessac, France
| | - Isabelle Bestel
- University of Bordeaux, CNRS, CBMN, UMR 5248, Institute of Chemistry and Biology of Membranes & Nano-objects (CBMN), Allée Geoffroy Saint Hilaire, Bât B14, 33600 Pessac, France
| | - Eduard Badarau
- University of Bordeaux, CNRS, CBMN, UMR 5248, Institute of Chemistry and Biology of Membranes & Nano-objects (CBMN), Allée Geoffroy Saint Hilaire, Bât B14, 33600 Pessac, France.
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5
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Geometrization for Energy Levels of Isotropic Hyperfine Hamiltonian Block and Related Central Spin Problems for an Arbitrarily Complex Set of Spin-1/2 Nuclei. Int J Mol Sci 2022; 23:ijms232315199. [PMID: 36499535 PMCID: PMC9739289 DOI: 10.3390/ijms232315199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 11/20/2022] [Accepted: 11/29/2022] [Indexed: 12/12/2022] Open
Abstract
Description of interacting spin systems relies on understanding the spectral properties of the corresponding spin Hamiltonians. However, the eigenvalue problems arising here lead to algebraic problems too complex to be analytically tractable. This is already the case for the simplest nontrivial (Kmax−1) block for an isotropic hyperfine Hamiltonian for a radical with spin-12 nuclei, where n nuclei produce an n-th order algebraic equation with n independent parameters. Systems described by such blocks are now physically realizable, e.g., as radicals or radical pairs with polarized nuclear spins, appear as closed subensembles in more general radical settings, and have numerous counterparts in related central spin problems. We provide a simple geometrization of energy levels in this case: given n spin-12 nuclei with arbitrary positive couplings ai, take an n-dimensional hyper-ellipsoid with semiaxes ai, stretch it by a factor of n+1 along the spatial diagonal (1, 1, …, 1), read off the semiaxes of thus produced new hyper-ellipsoid qi, augment the set {qi} with q0=0, and obtain the sought n+1 energies as Ek=−12qk2+14∑iai. This procedure provides a way of seeing things that can only be solved numerically, giving a useful tool to gain insights that complement the numeric simulations usually inevitable here, and shows an intriguing connection to discrete Fourier transform and spectral properties of standard graphs.
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Deviers J, Cailliez F, Gutiérrez BZ, Kattnig DR, de la Lande A. Ab initio derivation of flavin hyperfine interactions for the protein magnetosensor cryptochrome. Phys Chem Chem Phys 2022; 24:16784-16798. [PMID: 35775941 DOI: 10.1039/d1cp05804e] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The radicals derived from flavin adenine dinucleotide (FAD) are a corner stone of recent hypotheses about magnetoreception, including the compass of migratory songbirds. These models attribute a magnetic sense to coherent spin dynamics in radical pairs within the flavo-protein cryptochrome. The primary determinant of sensitivity and directionality of this process are the hyperfine interactions of the involved radicals. Here, we present a comprehensive computational study of the hyperfine couplings in the protonated and unprotonated FAD radicals in cryptochrome 4 from C. livia. We combine long (800 ns) molecular dynamics trajectories to accurate quantum chemistry calculations. Hyperfine parameters are derived using auxiliary density functional theory applied to cluster and hybrid QM/MM (Quantum Mechanics/Molecular Mechanics) models comprising the FAD and its significant surrounding environment, as determined by a detailed sensitivity analysis. Thanks to this protocol we elucidate the sensitivity of the hyperfine interaction parameters to structural fluctuations and the polarisation effect of the protein environment. We find that the ensemble-averaged hyperfine interactions are predominantly governed by thermally induced geometric distortions of the flavin. We discuss our results in view of the expected performance of these radicals as part of a magnetoreceptor. Our data could be used to parametrize spin Hamiltonians including not only average values but also standard deviations.
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Affiliation(s)
- Jean Deviers
- Living Systems Institute and Department of Physics, University of Exeter, Stocker Road, Exeter, Devon, EX4 4QD, UK.,Institut de Chimie Physique, CNRS UMR 8000, Université Paris-Saclay, 91405 Orsay, France.
| | - Fabien Cailliez
- Institut de Chimie Physique, CNRS UMR 8000, Université Paris-Saclay, 91405 Orsay, France.
| | - Bernardo Zúñiga Gutiérrez
- Departamento de Química, Universidad de Guadalajara, Blvd. Marcelino García Barragán 1421, C. P. 44430, Guadalajara Jal, Mexico
| | - Daniel R Kattnig
- Living Systems Institute and Department of Physics, University of Exeter, Stocker Road, Exeter, Devon, EX4 4QD, UK
| | - Aurélien de la Lande
- Institut de Chimie Physique, CNRS UMR 8000, Université Paris-Saclay, 91405 Orsay, France.
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7
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Pompe N, Illarionov B, Fischer M, Bacher A, Weber S. Completing the Picture: Determination of 13C Hyperfine Coupling Constants of Flavin Semiquinone Radicals by Photochemically Induced Dynamic Nuclear Polarization Spectroscopy. J Phys Chem Lett 2022; 13:5160-5167. [PMID: 35658481 DOI: 10.1021/acs.jpclett.2c00919] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
We investigate the electronic structure of flavin semiquinone radicals in terms of their 13C hyperfine coupling constants. Photochemically induced dynamic nuclear polarization (photo-CIDNP) spectroscopy was used to study both the neutral and anionic radical species of flavin mononucleotide (FMN) in bulk aqueous solution. Apart from universally 13C-labeled FMN, partially labeled isotopologues are used to increase sensitivity for nuclei exhibiting very small hyperfine couplings and to cope with spectral overlap. In addition, experimental findings are supported by quantum chemical calculations, and implications for the spin density distribution in free flavin radicals are discussed.
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Affiliation(s)
- Nils Pompe
- Institute of Physical Chemistry, University of Freiburg, 79104 Freiburg im Breisgau, Germany
| | - Boris Illarionov
- Hamburg School of Food Science, University of Hamburg, 20146 Hamburg, Germany
| | - Markus Fischer
- Hamburg School of Food Science, University of Hamburg, 20146 Hamburg, Germany
| | - Adelbert Bacher
- Department of Chemistry, Technical University of Munich, 85748 Garching, Germany
| | - Stefan Weber
- Institute of Physical Chemistry, University of Freiburg, 79104 Freiburg im Breisgau, Germany
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8
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Understanding flavin electronic structure and spectra. WIRES COMPUTATIONAL MOLECULAR SCIENCE 2022. [DOI: 10.1002/wcms.1541] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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9
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Wörner J, Chen J, Bacher A, Weber S. Non-classical disproportionation revealed by photo-chemically induced dynamic nuclear polarization NMR. MAGNETIC RESONANCE (GOTTINGEN, GERMANY) 2021; 2:281-290. [PMID: 37904753 PMCID: PMC10539781 DOI: 10.5194/mr-2-281-2021] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/20/2021] [Accepted: 04/07/2021] [Indexed: 11/01/2023]
Abstract
Photo-chemically induced dynamic nuclear polarization (photo-CIDNP) was used to observe the light-induced disproportionation reaction of 6,7,8-trimethyllumazine starting out from its triplet state to generate a pair of radicals comprising a one-electron reduced and a one-electron oxidized species. Our evidence is based on the measurement of two marker proton hyperfine couplings, A iso (H(6α )) and A iso (H(8α )), which we correlated to predictions from density functional theory. The ratio of these two hyperfine couplings is reversed in the oxidized and the reduced radical species. Observation of the dismutation reaction is facilitated by the exceptional C-H acidity of the methyl group at position 7 of 6,7,8-trimethyllumazine and the slow proton exchange associated with it, which leads to NMR-distinguishable anionic (TML- ) and neutral (TMLH) protonation forms.
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Affiliation(s)
- Jakob Wörner
- Institute of Physical Chemistry, Albert-Ludwigs-Universität
Freiburg, Freiburg, 79104, Germany
| | - Jing Chen
- Institute of Physical Chemistry, Albert-Ludwigs-Universität
Freiburg, Freiburg, 79104, Germany
| | - Adelbert Bacher
- Department of Chemistry, Technical University of Munich, Garching,
85748, Germany
| | - Stefan Weber
- Institute of Physical Chemistry, Albert-Ludwigs-Universität
Freiburg, Freiburg, 79104, Germany
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10
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Iuliano JN, Hall CR, Green D, Jones GA, Lukacs A, Illarionov B, Bacher A, Fischer M, French JB, Tonge PJ, Meech SR. Excited State Vibrations of Isotopically Labeled FMN Free and Bound to a Light-Oxygen-Voltage (LOV) Protein. J Phys Chem B 2020; 124:7152-7165. [PMID: 32786715 PMCID: PMC7533957 DOI: 10.1021/acs.jpcb.0c04943] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Flavoproteins are important blue light sensors in photobiology and play a key role in optogenetics. The characterization of their excited state structure and dynamics is thus an important objective. Here, we present a detailed study of excited state vibrational spectra of flavin mononucleotide (FMN), in solution and bound to the LOV-2 (Light-Oxygen-Voltage) domain of Avena sativa phototropin. Vibrational frequencies are determined for the optically excited singlet state and the reactive triplet state, through resonant ultrafast femtosecond stimulated Raman spectroscopy (FSRS). To assign the observed spectra, vibrational frequencies of the excited states are calculated using density functional theory, and both measurement and theory are applied to four different isotopologues of FMN. Excited state mode assignments are refined in both states, and their sensitivity to deuteration and protein environment are investigated. We show that resonant FSRS provides a useful tool for characterizing photoactive flavoproteins and is able to highlight chromophore localized modes and to record hydrogen/deuterium exchange.
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Affiliation(s)
- James N. Iuliano
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400, United States
| | | | - Dale Green
- School of Chemistry, University of East Anglia, Norwich NR4 7TJ, U.K
| | - Garth A. Jones
- School of Chemistry, University of East Anglia, Norwich NR4 7TJ, U.K
| | - Andras Lukacs
- Department of Biophysics, Medical School, University of Pecs, Szigeti ut 12, 7624 Pecs, Hungary
| | - Boris Illarionov
- Institut für Biochemie und Lebensmittelchemie, Universität Hamburg, Grindelallee 117, D-20146 Hamburg, Germany
| | - Adelbert Bacher
- Institut für Biochemie und Lebensmittelchemie, Universität Hamburg, Grindelallee 117, D-20146 Hamburg, Germany
- Department of Chemistry, Technical University of Munich, 85747 Garching, Germany
| | - Markus Fischer
- Institut für Biochemie und Lebensmittelchemie, Universität Hamburg, Grindelallee 117, D-20146 Hamburg, Germany
| | - Jarrod B. French
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400, United States
| | - Peter J. Tonge
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400, United States
| | - Stephen R. Meech
- School of Chemistry, University of East Anglia, Norwich NR4 7TJ, U.K
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11
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Affiliation(s)
- P J Hore
- Department of Chemistry, University of Oxford, Oxford, United Kingdom
| | - Konstantin L Ivanov
- International Tomography Center, Siberian Branch of the Russian Academy of Science, Novosibirsk 630090, Russia
| | - Michael R Wasielewski
- Department of Chemistry and Institute for Sustainability and Energy at Northwestern, Northwestern University, Evanston, Illinois 60208-3113, USA
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12
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Brosi R, Illarionov B, Heidinger L, Kim RR, Fischer M, Weber S, Bacher A, Bittl R, Schleicher E. Coupled Methyl Group Rotation in FMN Radicals Revealed by Selective Deuterium Labeling. J Phys Chem B 2020; 124:1678-1690. [PMID: 32011886 DOI: 10.1021/acs.jpcb.9b11331] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Flavin semiquinones are common intermediate redox states in flavoproteins, and thus, knowledge of their electronic structure is essential for fully understanding their chemistry and chemical versatility. In this contribution, we use a combination of high-field electron nuclear double resonance spectroscopy and selective deuterium labeling of flavin mononucleotide (FMN) with subsequent incorporation as cofactor into a variant Avena sativa LOV domain to extract missing traits of the electronic structure of a protein-bound FMN radical. From these experiments, precise values of small proton hyperfine and deuterium nuclear quadrupole couplings could be extracted. Specifically, isotropic hyperfine couplings of -3.34, -0.11, and +0.91 MHz were obtained for the protons H(6), H(9), and H(7α), respectively. These values are discussed in the light of specific protein-cofactor interactions. Furthermore, the temperature behavior of the H(7α) methyl-group rotation elicited by its energy landscape was analyzed in greater detail. Pronounced interplay between the two methyl groups at C(7) and C(8) of FMN could be revealed. Most strikingly, this rotational behavior could be modulated by selective deuterium editing.
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Affiliation(s)
- Richard Brosi
- Fachbereich Physik, Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Boris Illarionov
- Institut für Lebensmittelchemie, Universität Hamburg, Grindelallee 117, 20146 Hamburg, Germany
| | - Lorenz Heidinger
- Institut für Physikalische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104 Freiburg, Germany
| | - Ryu-Ryun Kim
- Institut für Lebensmittelchemie, Universität Hamburg, Grindelallee 117, 20146 Hamburg, Germany
| | - Markus Fischer
- Institut für Lebensmittelchemie, Universität Hamburg, Grindelallee 117, 20146 Hamburg, Germany
| | - Stefan Weber
- Institut für Physikalische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104 Freiburg, Germany
| | - Adelbert Bacher
- Institut für Lebensmittelchemie, Universität Hamburg, Grindelallee 117, 20146 Hamburg, Germany.,Fakultät für Chemie, Technische Universität München, Lichtenbergstr. 4, 80247 Garching, Germany
| | - Robert Bittl
- Fachbereich Physik, Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Erik Schleicher
- Institut für Physikalische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104 Freiburg, Germany
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