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Püschel D, Hédé S, Maisuls I, Höfert SP, Woschko D, Kühnemuth R, Felekyan S, Seidel CAM, Czekelius C, Weingart O, Strassert CA, Janiak C. Enhanced Solid-State Fluorescence of Flavin Derivatives by Incorporation in the Metal-Organic Frameworks MIL-53(Al) and MOF-5. Molecules 2023; 28:molecules28062877. [PMID: 36985849 PMCID: PMC10055669 DOI: 10.3390/molecules28062877] [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: 01/25/2023] [Revised: 03/14/2023] [Accepted: 03/17/2023] [Indexed: 03/30/2023] Open
Abstract
The flavin derivatives 10-methyl-isoalloxazine (MIA) and 6-fluoro-10-methyl-isoalloxazine (6F-MIA) were incorporated in two alternative metal-organic frameworks, (MOFs) MIL-53(Al) and MOF-5. We used a post-synthetic, diffusion-based incorporation into microcrystalline MIL-53 powders with one-dimensional (1D) pores and an in-situ approach during the synthesis of MOF-5 with its 3D channel network. The maximum amount of flavin dye incorporation is 3.9 wt% for MIA@MIL-53(Al) and 1.5 wt% for 6F-MIA@MIL-53(Al), 0.85 wt% for MIA@MOF-5 and 5.2 wt% for 6F-MIA@MOF-5. For the high incorporation yields the probability to have more than one dye molecule in a pore volume is significant. As compared to the flavins in solution, the fluorescence spectrum of these flavin@MOF composites is broadened at the bathocromic side especially for MIA. Time-resolved spectroscopy showed that multi-exponential fluorescence lifetimes were needed to describe the decays. The fluorescence-weighted lifetime of flavin@MOF of 4 ± 1 ns also corresponds to those in solution but is significantly prolonged compared to the solid flavin dyes with less than 1 ns, thereby confirming the concept of "solid solutions" for dye@MOF composites. The fluorescence quantum yield (ΦF) of the flavin@MOF composites is about half of the solution but is significantly higher compared to the solid flavin dyes. Both the fluorescence lifetime and quantum yield of flavin@MOF decrease with the flavin loading in MIL-53 due to the formation of various J-aggregates. Theoretical calculations using plane-wave and QM/MM methods are in good correspondence with the experimental results and explain the electronic structures as well as the photophysical properties of crystalline MIA and the flavin@MOF composites. In the solid flavins, π-stacking interactions of the molecules lead to a charge transfer state with low oscillator strength resulting in aggregation-caused quenching (ACQ) with low lifetimes and quantum yields. In the MOF pores, single flavin molecules represent a major population and the computed MIA@MOF structures do not find π-stacking interactions with the pore walls but only weak van-der-Waals contacts which reasons the enhanced fluorescence lifetime and quantum yield of the flavins in the composites compared to their neat solid state. To analyze the orientation of flavins in MOFs, we measured fluorescence anisotropy images of single flavin@MOF-5 crystals and a static ensemble flavin@MIL53 microcrystals, respectively. Based on image information, anisotropy distributions and overall curve of the time-resolved anisotropy curves combined with theoretical calculations, we can prove that all fluorescent flavins species have a defined and rather homogeneous orientation in the MOF framework. In MIL-53, the transition dipole moments of flavins are orientated along the 1D channel axis, whereas in MOF-5 we resolved an average orientation that is tilted with respect to the cubic crystal lattice. Notably, the more hydrophobic 6F-MIA exhibits a higher degree order than MIA. The flexible MOF MIL-53(Al) was optimized essentially to the experimental large-pore form in the guest-free state with QuantumEspresso (QE) and with MIA molecules in the pores the structure contracted to close to the experimental narrow-pore form which was also confirmed by PXRD. In summary, the incorporation of flavins in MOFs yields solid-state materials with enhanced rigidity, stabilized conformation, defined orientation and reduced aggregations of the flavins, leading to increased fluorescence lifetime and quantum yield as controllable photo-luminescent and photo-physical properties.
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Affiliation(s)
- Dietrich Püschel
- Institut für Anorganische Chemie und Strukturchemie, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, D-40225 Düsseldorf, Germany
| | - Simon Hédé
- Institut für Theoretische Chemie und Computerchemie, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, D-40225 Düsseldorf, Germany
| | - Iván Maisuls
- Institut für Anorganische und Analytische Chemie, CeNTech, CiMIC, SoN, Westfälische Wilhelms-Universität Münster, Heisenbergstraße 11, D-48149 Münster, Germany
| | - Simon-Patrick Höfert
- Institut für Anorganische Chemie und Strukturchemie, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, D-40225 Düsseldorf, Germany
| | - Dennis Woschko
- Institut für Anorganische Chemie und Strukturchemie, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, D-40225 Düsseldorf, Germany
| | - Ralf Kühnemuth
- Institut für Physikalische Chemie, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, D-40225 Düsseldorf, Germany
| | - Suren Felekyan
- Institut für Physikalische Chemie, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, D-40225 Düsseldorf, Germany
| | - Claus A M Seidel
- Institut für Physikalische Chemie, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, D-40225 Düsseldorf, Germany
| | - Constantin Czekelius
- Institut für Organische Chemie und Makromolekulare Chemie, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, D-40225 Düsseldorf, Germany
| | - Oliver Weingart
- Institut für Theoretische Chemie und Computerchemie, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, D-40225 Düsseldorf, Germany
| | - Cristian A Strassert
- Institut für Anorganische und Analytische Chemie, CeNTech, CiMIC, SoN, Westfälische Wilhelms-Universität Münster, Heisenbergstraße 11, D-48149 Münster, Germany
| | - Christoph Janiak
- Institut für Anorganische Chemie und Strukturchemie, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, D-40225 Düsseldorf, Germany
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Haj Hassani Sohi T, Maass F, Czekelius C, Suta M, Vasylyeva V. Co-crystallization of organic chromophore roseolumiflavin and effect on its optical characteristics. CrystEngComm 2022. [DOI: 10.1039/d2ce00589a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Three roseolumiflavin co-crystals are designed to elucidate the accessibility of flavins for the targeted tuning of luminescence in the solid state.
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Affiliation(s)
- Takin Haj Hassani Sohi
- Laboratory for Molecular Crystal Engineering, Department of Inorganic Chemistry and Structural Chemistry I, Heinrich-Heine-University Duesseldorf, Universitaetstr. 1, 40225 Duesseldorf, Germany
| | - Felix Maass
- Laboratory for Molecular Crystal Engineering, Department of Inorganic Chemistry and Structural Chemistry I, Heinrich-Heine-University Duesseldorf, Universitaetstr. 1, 40225 Duesseldorf, Germany
| | - Constantin Czekelius
- Laboratory for Asymmetric Synthesis and Catalysis, Department of Organic Chemistry and Macromolecular Chemistry, Heinrich-Heine-University Duesseldorf, Universitaetstr. 1, 40225 Duesseldorf, Germany
| | - Markus Suta
- Laboratory for Inorganic Photoactive Materials, Department of Inorganic Chemistry and Structural Chemistry II, Heinrich-Heine-University Duesseldorf, Universitaetstr. 1, 40225 Duesseldorf, Germany
| | - Vera Vasylyeva
- Laboratory for Molecular Crystal Engineering, Department of Inorganic Chemistry and Structural Chemistry I, Heinrich-Heine-University Duesseldorf, Universitaetstr. 1, 40225 Duesseldorf, Germany
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Oka Y. Cesium Cation Complexation by a Flavin Receptor via Self-Assembly and Deprotonation. ACS OMEGA 2020; 5:21226-21230. [PMID: 32875259 PMCID: PMC7450633 DOI: 10.1021/acsomega.0c03006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Accepted: 07/30/2020] [Indexed: 06/11/2023]
Abstract
This study focuses on the self-assembly of a new flavin compound and its scaffolding function for a Cs+ ion. 7,8-Dimethyl-10-[4'-(methoxycarbonyl)phenyl]-isoalloxazine (FlH-MB) displays self-assembly in a DMSO solution and has strong dependence on the solvent. In the DMSO solution, both the resulting scaffold and the deprotonation of FlH-MB were demonstrated to induce complex formation with a Cs+ ion, which was investigated by UV-vis, 1H NMR, and fluorescence titrations. This complex formation involves both Coulombic and cation-π interactions through the Fl- site in an Fl--MB dimer.
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Affiliation(s)
- Yoshimi Oka
- Research Promotion Institute, Oita University, 700 Dannoharu, Oita 870-1192, Japan
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Brisker-Klaiman D, Dreuw A. On the influence of dimerisation of lumiflavin in aqueous solution on its optical spectra – a quantum chemical study. Mol Phys 2019. [DOI: 10.1080/00268976.2019.1616843] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Daria Brisker-Klaiman
- Interdisciplinary Center for Scientific Computing, Heidelberg University, Heidelberg, Germany
| | - Andreas Dreuw
- Interdisciplinary Center for Scientific Computing, Heidelberg University, Heidelberg, Germany
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Bracker M, Dinkelbach F, Weingart O, Kleinschmidt M. Impact of fluorination on the photophysics of the flavin chromophore: a quantum chemical perspective. Phys Chem Chem Phys 2019; 21:9912-9923. [DOI: 10.1039/c9cp00805e] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
10-Methylisoalloxazine (MIA) and its fluorinated derivatives (6-9F-MIA) were investigated by means of quantum chemistry, looking into the influence of fluorination on fluorescence, absorption and inter-system crossing (ISC) in vacuum and in aqueous solution.
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Affiliation(s)
- Mario Bracker
- Institut für Theoretische Chemie und Computerchemie
- Heinrich-Heine-Universität Düsseldorf
- 40225 Düsseldorf
- Germany
| | - Fabian Dinkelbach
- Institut für Theoretische Chemie und Computerchemie
- Heinrich-Heine-Universität Düsseldorf
- 40225 Düsseldorf
- Germany
| | - Oliver Weingart
- Institut für Theoretische Chemie und Computerchemie
- Heinrich-Heine-Universität Düsseldorf
- 40225 Düsseldorf
- Germany
| | - Martin Kleinschmidt
- Institut für Theoretische Chemie und Computerchemie
- Heinrich-Heine-Universität Düsseldorf
- 40225 Düsseldorf
- Germany
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Suzuki H, Inoue R, Kawamorita S, Komiya N, Imada Y, Naota T. Highly fluorescent flavins: rational molecular design for quenching protection based on repulsive and attractive control of molecular alignment. Chemistry 2015; 21:9171-8. [PMID: 25962532 DOI: 10.1002/chem.201406346] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Indexed: 11/05/2022]
Abstract
Unprecedented intense fluorescent emission was observed for a variety of flavin compounds bearing a perpendicular cyclic imide moiety at the C7 position of an isoalloxazine platform. A series of alloxan-substituted flavins was prepared selectively by reduction of the corresponding N-aryl-2-nitro-5-alkoxyanilines with zinc dust and subsequent reaction with alloxan monohydrate in the presence of boric acid. Analogues bearing oxazolidine-2,4-dione functionality were obtained on methylation of the alloxan-substituted flavins with methyl iodide and subsequent rearrangement in the presence of an inorganic base. The flavin compounds exhibit intense white-green fluorescent emission in the solution state under UV excitation at 298 K, with emission efficiencies Φ298 K greater than 0.55 in CH3 CN, which are higher than the values for all reported flavin compounds under similar conditions. The highest Φ298 K value of 0.70 was obtained in CH3 CN for isoalloxazine bearing C7-alloxan and N10-2,6-diisopropylphenyl groups. The temperature dependence of the emission intensities indicates that the pronounced emission properties at 298 K are attributable to the highly heat resistant properties towards emission decay with increasing temperature. Mechanistic studies, including X-ray diffraction analysis, revealed that the good emission properties and high heat resistance of the alloxan-substituted flavins are due to a synergetic effect of the associative nature of the C7-alloxan unit and the repulsive nature of the perpendicular bulky substituents at the C7 and N10 positions.
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Affiliation(s)
- Haruka Suzuki
- Department of Chemistry, Graduate School of Engineering Science, Osaka University, Machikaneyama, Toyonaka, Osaka 560-8531 (Japan)
| | - Ryo Inoue
- Department of Chemistry, Graduate School of Engineering Science, Osaka University, Machikaneyama, Toyonaka, Osaka 560-8531 (Japan)
| | - Soichiro Kawamorita
- Department of Chemistry, Graduate School of Engineering Science, Osaka University, Machikaneyama, Toyonaka, Osaka 560-8531 (Japan)
| | - Naruyoshi Komiya
- Department of Chemistry, Graduate School of Engineering Science, Osaka University, Machikaneyama, Toyonaka, Osaka 560-8531 (Japan)
| | - Yasushi Imada
- Department of Chemistry, Graduate School of Engineering Science, Osaka University, Machikaneyama, Toyonaka, Osaka 560-8531 (Japan).,Present address: Department of Chemical Science and Technology, Institute of Technology and Science, Tokushima University, Minamijosanjima, Tokushima 770-8506 (Japan)
| | - Takeshi Naota
- Department of Chemistry, Graduate School of Engineering Science, Osaka University, Machikaneyama, Toyonaka, Osaka 560-8531 (Japan).
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Langer J, Günther A, Seidenbecher S, Berden G, Oomens J, Dopfer O. Probing protonation sites of isolated flavins using IR spectroscopy: from lumichrome to the cofactor flavin mononucleotide. Chemphyschem 2014; 15:2550-62. [PMID: 24895155 DOI: 10.1002/cphc.201402146] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Indexed: 11/06/2022]
Abstract
Infrared spectra of the isolated protonated flavin molecules lumichrome, lumiflavin, riboflavin (vitamin B2), and the biologically important cofactor flavin mononucleotide are measured in the fingerprint region (600-1850 cm(-1)) by means of IR multiple-photon dissociation (IRMPD) spectroscopy. Using density functional theory calculations, the geometries, relative energies, and linear IR absorption spectra of several low-energy isomers are calculated. Comparison of the calculated IR spectra with the measured IRMPD spectra reveals that the N10 substituent on the isoalloxazine ring influences the protonation site of the flavin. Lumichrome, with a hydrogen substituent, is only stable as the N1-protonated tautomer and protonates at N5 of the pyrazine ring. The presence of the ribityl unit in riboflavin leads to protonation at N1 of the pyrimidinedione moiety, and methyl substitution in lumiflavin stabilizes the tautomer that is protonated at O2. In contrast, flavin mononucleotide exists as both the O2- and N1-protonated tautomers. The frequencies and relative intensities of the two C=O stretch vibrations in protonated flavins serve as reliable indicators for their protonation site.
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Affiliation(s)
- Judith Langer
- Technische Universität Berlin, Institut für Optik und Atomare Physik, Hardenbergstraße 36, D-10623 Berlin (Germany); Current address: Parque Tecnologico de San Sebastian, Paseo Miramon 182, Edif C, 20009 San Sebastian (Spain)
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Daďová J, Kümmel S, Feldmeier C, Cibulková J, Pažout R, Maixner J, Gschwind RM, König B, Cibulka R. Aggregation Effects in Visible-Light Flavin Photocatalysts: Synthesis, Structure, and Catalytic Activity of 10-Arylflavins. Chemistry 2012. [DOI: 10.1002/chem.201202488] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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9
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Kobayashi A, Ohbayashi K, Aoki R, Chang HC, Kato M. Synthesis, structure and photophysical properties of a flavin-based platinum(II) complex. Dalton Trans 2011; 40:3484-9. [PMID: 21359278 DOI: 10.1039/c0dt01139h] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We synthesized a thiosemicarbazone-functionalized flavin (Fl-(H)TSC: 2-[2-(3,4-dihydro-7,8-dimethyl-2,4-dioxobenzo[g]pteridin-10(2H)-yl)ethylidene]-hydrazinecarbothioamide) and its Pt(II) complex [Pt(Fl-TSC)(2)], and characterized it using X-ray diffraction, UV-visible absorption and luminescence spectroscopy. X-ray structural analysis for [Pt(Fl-TSC)(2)] revealed that the structure of the isoalloxazine part was almost the same as that in lumiflavin (7,8,10-trimethylisoalloxazine), and the thiosemicarbazone moiety acted as a bidentate ligand to form a PtS(2)N(2) planar conformation. UV-visible absorption and luminescence spectra of these compounds were very similar to those of riboflavin, but the emission intensity and the lifetime decreased considerably. Theoretical calculations suggested that the charge-separated state (Fl˙(-)-TSC˙(+)) contributed to the faster quenching from the (1)π-π* emission state.
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Affiliation(s)
- Atsushi Kobayashi
- Division of Chemistry, Faculty of Science, Hokkaido University, North-10 West-8, Sapporo 060-0810, Japan.
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10
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Rohlíček J, Cibulka R, Cibulková J, Maixner J, Hušák M. 10-Methylisoalloxazine 5-oxide from synchrotron powder diffraction data. Acta Crystallogr Sect E Struct Rep Online 2010; 66:o3350-1. [PMID: 21589621 PMCID: PMC3011510 DOI: 10.1107/s1600536810048932] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2010] [Accepted: 11/23/2010] [Indexed: 11/11/2022]
Abstract
The title compound [systematic name: 10-methylbenzo[g]pteridine-2,4(3H,10H)-dione 5-oxide], C11H8N4O3, consists of a large rigid isoalloxazine group which is approximately planar (r.m.s. deviation = 0.037 Å). In the crystal, intermolecular N—H⋯O hydrogen bonds link the molecules into centrosymmetric dimers. Dimers related by translation along the c axis form stacks through π–π interactions [centroid–centroid distances = 3.560 (5) and 3.542 (5) Å]. Weak intermolecular C—H⋯O interactions further consolidate the crystal packing.
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11
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The photophysics of flavins: What makes the difference between gas phase and aqueous solution? J Photochem Photobiol A Chem 2008. [DOI: 10.1016/j.jphotochem.2008.03.015] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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12
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Choe YK, Nagase S, Nishimoto K. Theoretical study of the electronic spectra of oxidized and reduced states of lumiflavin and its derivative. J Comput Chem 2007; 28:727-39. [PMID: 17226839 DOI: 10.1002/jcc.20533] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Time-dependent density functional theory has been applied to investigate the electronic absorption spectrum of oxidized and reduced lumiflavin and its derivative, 8-NH(2)-lumiflavin. The calculations allow the authors to explain the origin of the difference in spectral features between oxidized and reduced states of lumiflavin. For the reduced lumiflavin, a reasonable assignment of the experimental spectrum has been made for the first time. Furthermore, the results obtained reveal that the NH(2) group plays a critical role in shaping the spectral features of 8-NH(2)-lumiflavin, and offer a reasonable explanation for the spectral changes upon substituting the NH(2) group for the CH(3) group of lumiflavin.
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Affiliation(s)
- Yoong-Kee Choe
- Research Institute for Computational Sciences (RICS), National Institute of Advanced Industrial Science and Technology (AIST), Centeral-2, Umezono 1-1-1, Tsukuba 305-8578, Japan.
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Climent T, González-Luque R, Merchán M, Serrano-Andrés L. Theoretical Insight into the Spectroscopy and Photochemistry of Isoalloxazine, the Flavin Core Ring. J Phys Chem A 2006; 110:13584-90. [PMID: 17165886 DOI: 10.1021/jp065772h] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The electronic singlet-singlet and singlet-triplet electronic transitions of the isoalloxazine ring of the flavin core are studied using second-order perturbation theory within the framework of the CASPT2//CASSCF protocol. The main features of the absorption spectrum are computed at 3.09, 4.28, 4.69, 5.00, and 5.37 eV. The lowest singlet (S1) and triplet (T1) excited states are found to be both of pi character with a singlet-triplet splitting of 0.57 eV. On the basis of the analysis of the computed spin-orbit couplings and the potential energy hypersurfaces built for the relevant excited states, the intrinsic mechanism for photoinduced population of T1 is discussed. Upon light absorption, evolution of the lowest singlet excited state along the relaxation pathway leads ultimately to the population of the lowest triplet state, which is mediated by a singlet-triplet crossing with a state of npi* type. Subsequently a radiationless decay toward T1 through a conical intersection takes place. The intersystem crossing mechanism and the internal conversion processes documented here provide a plausible route to access the lowest triplet state, which has a key role in the photochemistry of the flavin core ring and is mainly responsible for the reactivity of the system.
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Affiliation(s)
- Teresa Climent
- Instituto de Ciencia Molecular, Universitat de València, Apartado 22085, ES-46071 Valencia, Spain
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Kaim W. Die vielseitige Chemie der 1,4-Diazine: Organische, anorganische und biochemische Aspekte. Angew Chem Int Ed Engl 2006. [DOI: 10.1002/ange.19830950305] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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15
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Kowalczyk RM, Schleicher E, Bittl R, Weber S. The photoinduced triplet of flavins and its protonation states. J Am Chem Soc 2005; 126:11393-9. [PMID: 15355123 DOI: 10.1021/ja049554i] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The photogenerated triplet states of riboflavin and flavin mononucleotide (FMN) have been examined by time-resolved electron paramagnetic resonance (EPR) spectroscopy at low temperature (T = 80 K). Because of the high time resolution of the utilized EPR instrumentation, the triplets are for the first time observed in the nonequilibrated electron-spin polarized state and not in their equilibrated forms with the population of the triplet sublevels governed by Boltzmann distribution. The electron-spin polarization pattern directly reflects the anisotropy of the intersystem crossing from the excited singlet-state precursor. Spectral analysis of the resulting enhanced absorptive and emissive EPR signals yields the zero-field splitting parameters, |D| and |E|, and the zero-field populations of the triplet at high accuracy. These parameters are sensitive probes for the protonation state of the flavin's isoalloxazine ring, as becomes evident by a comparison of the spectra recorded at different pH values of the solvent. The three protonation states of the flavins can furthermore be distinguished by the kinetics of the transient EPR signals, which are dominated by spin-lattice relaxation. The fastest decays are observed for the protonated FMN and riboflavin triplets, followed by the deprotonated flavin triplets. Slow decays are measured for the triplet states of neutral FMN and riboflavin. Because proton transfer is found to be slow on the time scale of spin-polarized triplet detection by transient EPR, the pH-dependent spin-relaxation and zero-field splitting parameters offer a novel approach to probe the protonation state of flavins in their singlet ground state through the characterization of their triplet-state properties.
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Affiliation(s)
- Radoslaw M Kowalczyk
- Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
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Koch M, Breithaupt C, GerhardtHaase S, Weber S, Cushman M, Huber R, Bacher A, Fischer M. Structural basis of charge transfer complex formation by riboflavin bound to 6,7-dimethyl-8-ribityllumazine synthase. ACTA ACUST UNITED AC 2004; 271:3208-14. [PMID: 15265040 DOI: 10.1111/j.1432-1033.2004.04253.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The amino acid residue tryptophan 27 of 6,7-dimethyl-8-ribityllumazine synthase of the yeast Schizosaccharomyces pombe was replaced by tyrosine. The structures of the W27Y mutant protein in complex with riboflavin, the substrate analogue 5-nitroso-6-ribitylamino-2,4(1H,3H)-pyrimidinedione, and the product analogue 6-carboxyethyl-7-oxo-8-ribityllumazine, were determined by X-ray crystallography at resolutions of 2.7-2.8 A. Whereas the indole system of W27 forms a coplanar pi-complex with riboflavin, the corresponding phenyl ring in the W27Y mutant establishes only peripheral contact with the heterocyclic ring system of the bound riboflavin. These findings provide an explanation for the absence of the long wavelength shift in optical absorption spectra of riboflavin bound to the mutant enzyme. The structures of the mutants are important tools for the interpretation of the unusual physical properties of riboflavin in complex with lumazine synthase.
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Affiliation(s)
- Michael Koch
- Abteilung Strukturforschung, Max-Planck-Institut für Biochemie, Martinsried, Germany
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Rodríguez-Otero J, Martínez-Núñez E, Peña-Gallego A, Vázquez SA. The role of aromaticity in the planarity of lumiflavin. J Org Chem 2002; 67:6347-52. [PMID: 12201752 DOI: 10.1021/jo011159c] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ab initio MP2/6-31G(d,p) and density functional theory B3LYP/6-31G(d,p) calculations were performed to investigate the molecular structure of the active part of flavins in the oxidized and reduced forms, using lumiflavin as a model compound. The possible aromatic character of these systems was explored by using the following aromaticity indexes: nucleus-independent chemical shifts, the anisotropy of the magnetic susceptibility, the Bird index, and natural bond orbital analysis. To provide further insight, calculations on the 2+ charged species were also carried out. Both the MP2 and B3LYP computations predict a planar conformation for the oxidized form and a bent structure for the reduced form, in agreement with previous experience. For both the oxidized and reduced states, ring A is found to be the most aromatic, as expected. The calculations suggest that the folding in the reduced form is mainly a result of electronic preferences rather than steric hindrance.
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Affiliation(s)
- Jesús Rodríguez-Otero
- Departamento de Química Física, Universidad de Santiago de Compostela, 15706 Santiago de Compostela, Spain
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Reibenspies JH, Guo F, Rizzo CJ. X-ray crystal structures of conformationally biased flavin models. Org Lett 2000; 2:903-6. [PMID: 10768182 DOI: 10.1021/ol005539g] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
X-ray crystal structures of the oxidized form of three conformationally biased flavin models are reported. Models 4 and 5 show significant distortion, which contributes to their bias for the fully reduced form.
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Affiliation(s)
- J H Reibenspies
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, USA
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Lennon BW, Williams CH, Ludwig ML. Crystal structure of reduced thioredoxin reductase from Escherichia coli: structural flexibility in the isoalloxazine ring of the flavin adenine dinucleotide cofactor. Protein Sci 1999; 8:2366-79. [PMID: 10595539 PMCID: PMC2144213 DOI: 10.1110/ps.8.11.2366] [Citation(s) in RCA: 91] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Catalysis by thioredoxin reductase (TrxR) from Escherichia coli requires alternation between two domain arrangements. One of these conformations has been observed by X-ray crystallography (Waksman G, Krishna TSR, Williams CH Jr, Kuriyan J, 1994, J Mol Biol 236:800-816). This form of TrxR, denoted FO, permits the reaction of enzyme-bound reduced FAD with a redox-active disulfide on TrxR. As part of an investigation of conformational changes and intermediates in catalysis by TrxR, an X-ray structure of the FO form of TrxR with both the FAD and active site disulfide reduced has been determined. Reduction after crystallization resulted in significant local conformation changes. The isoalloxazine ring of the FAD cofactor, which is essentially planar in the oxidized enzyme, assumes a 34 degree "butterfly" bend about the N(5)-N(10) axis in reduced TrxR. Theoretical calculations reported by others predict ring bending of 15-28 degrees for reduced isoalloxazines protonated at N(1). The large bending in reduced TrxR is attributed in part to steric interactions between the isoalloxazine ring and the sulfur of Cys138, formed by reduction of the active site disulfide, and is accompanied by changes in the positions and interactions of several of the ribityl side-chain atoms of FAD. The bending angle in reduced TrxR is larger than that for any flavoprotein in the Protein Data Bank. Distributions of bending angles in published oxidized and reduced flavoenzyme structures are different from those found in studies of free flavins, indicating that the protein environment has a significant effect on bending.
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Affiliation(s)
- B W Lennon
- Department of Biological Chemistry, The University of Michigan, Ann Arbor 48109, USA
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Semiempirical and ab initio study of closed and open shell derivatives of 10-methylisoalloxazine: a model of flavin redox states. ACTA ACUST UNITED AC 1996. [DOI: 10.1016/0166-1280(96)04491-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Leenders R, Bastiaens P, Lunsche R, Van Hoek A, J.W.G. Visser A. Rotational resolution of methyl-group substitution and anisotropic rotation of flavins as revealed by picosecond-resolved fluorescence depolarization. Chem Phys Lett 1990. [DOI: 10.1016/0009-2614(90)87195-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Murgolo NJ, Cerami A, Henderson GB. Biomedical science and the third world. Under the volcano. Trypanothione reductase. Ann N Y Acad Sci 1989; 569:193-200. [PMID: 2698087 DOI: 10.1111/j.1749-6632.1989.tb27369.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- N J Murgolo
- Laboratory of Medical Biochemistry, Rockefeller University, New York, New York 10021
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27
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Ghosh BK, Chakravorty A. Electrochemical studies of ruthenium compounds part I. Ligand oxidation levels. Coord Chem Rev 1989. [DOI: 10.1016/0010-8545(89)80027-x] [Citation(s) in RCA: 205] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Abstract
The crystal structure of human glutathione reductase has been established at 1.54 A resolution using a restrained least-squares refinement method. Based on 77,690 independent reflections of better than 10 A resolution, a final R-factor of 18.6% was obtained with a model obeying standard geometry within 0.025 A in bond lengths and 2.4 degrees in bond angles. The final 2Fo-Fc electron density map allows for the distinction of carbon, nitrogen and oxygen atoms with temperature factors below about 25 A2. Apart from 461 amino acid residues and the prosthetic group FAD, the model contains 524 solvent molecules, about 118 of which can be considered an integral part of the enzyme. The largest solvent cluster is at the dimer interface and contains 104 interconnected solvent molecules, part of which are organized in a warped sheet-like structure. The main-chain dihedral angles are well-concentrated in the allowed regions of the Ramachandran plot. The spread of dihedral angles in beta-pleated sheets is much larger than in alpha-helices and especially in alpha-helix cores, indicating the higher plasticity of beta-structures. The analysis revealed a large amount of 3(10)-helix. The side-chain conformations cluster at the staggered positions, and show well-defined preferences. Also, a mobility gradient is observed for side-chains. Non-polar and polar side-chains show average temperature factor increases per bond of 10% and 25%, respectively. A number of alternative conformations of internal side-chains, in particular serines and methionines, have been detected. The extended FAD molecule also shows a mobility gradient between the very rigid flavin (mean value of B) = 8.7 A2) and the more mobile adenine (mean value of B = 16.2 A2). The entire active center is particularly well ordered, with temperature factors around 10 A2. The dimer interface consists of a rigid contact area, which is well conserved in the Escherichia coli enzyme, and a flexible area that is not. Altogether, the buried surfaces at the crystal contacts are half as large as at the dimer interface, but less specific. The refined structure shows clearly that there are no buried cations compensating the charge of the pyrophosphate moiety of FAD. The flavin deviates slightly from standard geometry, which is possibly caused by the polypeptide environment. In contrast to an earlier interpretation, atom N5 of the flavin can accommodate a proton, and it is conceivable that this proton proceeds to the redox-active disulfide.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- P A Karplus
- Institut für Organische Chemie und Biochemie der Universität, Freiburg i.Br., F.R. Germany
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Inoue M, Okuda Y, Ishida T, Nakagaki M. On the interaction between flavin-adenine rings and between flavin-indole rings by X-ray structural studies. Arch Biochem Biophys 1983; 227:52-70. [PMID: 6639083 DOI: 10.1016/0003-9861(83)90347-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Two crystal structures of 7,8-dimethylisoalloxazine-10-acetic acid:adenine-9-ylethylamine(1:1)hepatahydrate and 7,8-dimethylisoalloxazine-10-acetic acid:L-tryptophan methylester(1:1)heptahydrate complexes were determined as models for the flavin-adenine and flavin-indole interactions, respectively. In the former complex, both molecules were connected by Hoogsteen-type hydrogen bonds between the pyrimidinoid portion of flavin and the adenine, in addition to the normal stacking of both aromatic rings. On the other hand, parallel stackings and intermolecular vertical spacings less than the normal van der Waals separation distance were observed between the flavin and indole rings of the latter complex, indicative of the pi D-pi A charge-transfer interaction in their ground states. Comparing with the X-ray findings of related complexes, we discussed the interaction modes between flavin and adenine rings and between flavin and indole rings.
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Smith WW, Pattridge KA, Ludwig ML, Petsko GA, Tsernoglou D, Tanaka M, Yasunobu KT. Structure of oxidized flavodoxin from Anacystis nidulans. J Mol Biol 1983; 165:737-53. [PMID: 6406674 DOI: 10.1016/s0022-2836(83)80277-0] [Citation(s) in RCA: 79] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The structure of oxidized flavodoxin from the cyanobacterium Anacystis nidulans has been determined at 2.5 A resolution with phases calculated from ethylmercury phosphate and dimercuriacetate derivatives. The determination of partial sequences, including a total of 85 residues, has assisted in the interpretation of the electron density. Preliminary refinement of a partial model (1072 atoms) has reduced R to 0.349 for the 10.997 reflections between 2.0 and 5.0 A with 1 greater than 2 sigma. The polypeptide backbone, which comprises 167 residues in the current model, adopts the familiar beta-alpha-beta conformation found in other flavodoxins and in the nucleotide-binding domains of the pyridine-nucleotide dehydrogenases, with five parallel strands in the central sheet. Comparison with flavodoxin from Clostridium MP (138 residues) shows that extra residues of A. nidulans flavodoxin are accommodated in a major insertion about 20 residues in length, which forms a lobe adjacent to the fifth strand of parallel sheet, and in additions to several external segments. Residues added between the fourth sheet strand and the start of the third helix alter the environment of the pyrimidine end of the flavin mononucleotide ring. The flavin mononucleotide phosphate binds to the start of helix 1, interacting with hydroxyamino acids and with main-chain amide groups. Two hydrophobic residues, both tentatively identified as Trp, enclose the isoalloxazine ring; the solvent-exposed Trp is nearly parallel to the flavin ring. The hydrophobic environment provided by these residues must be partly responsible for the pronounced vibrational resolution of the flavin spectrum near 450 nm. The flavin ring is tilted relative to its orientation in Clostridium MP flavodoxin. In addition, atoms N-3 and O-2 alpha of the isoalloxazine appear to form hydrogen bonds to the backbone at CO97 and NH99 in a conformation entirely different from that found in Clostridium MP flavodoxin but structurally analogous to Desulfovibrio vulgaris flavodoxin.
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Kaim W. The Versatile Chemistry of 1,4-Diazines: Organic, Inorganic and Biochemical Aspects. ACTA ACUST UNITED AC 1983. [DOI: 10.1002/anie.198301713] [Citation(s) in RCA: 86] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Inoue M, Shibata M, Kondo Y, Ishida T. Role of tryptophanyl and tyrosyl residues of flavoproteins in binding with flavin coenzymes. X-ray structural studies using model complexes. Biochemistry 1981; 20:2936-45. [PMID: 7248260 DOI: 10.1021/bi00513a034] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The crystal structures of 7,8-dimethylisoalloxazine-10-acetic acid-tryptamine (1:1) tetrahydrate and 7,8-dimethylisoalloxazine-10-acetic acid-tyramine (1:1) tetrahydrate complexes were determined by the X-ray diffraction method, as models for flavin-tryptophan and flavin-tyrosine interactions in flavoproteins. The observed parallel stackings and the intermolecular spacing distances, which were less than the normal van der Waals separation between the isoalloxazine and indole rings and between the isoalloxazine and phenol rings, suggest the existence of charge-transfer interactions in their ground states. The indole and phenol rings interact with the pyrimindinoid and pyrazinoid portions of the isoalloxazine ring and have short contacts, less than 3.4 A, with the reduction site (N1 and N5 atoms) of this ring. This suggests that the reduction of oxidized flavin to the semiquinone state may be facilitated by charge transfer from the former rings to the N1 and N5 atoms. Absorption difference spectra showed that both complexes associate with equimolar ratios in solution as well as in the crystalline state and that they have the same charge-transfer bands and association constants as flavin mononucleotide (FMN)-Trp and FMN-Tyr complexes, respectively. On the other hand, proton magnetic resonance spectra suggested that in solution, the stacking modes of the indole and phenol rings to the isoalloxazine ring are different from those observed in the crystal structures and both aromatic rings are stacked over the whole of the isoalloxazine ring.
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Eweg JK, Müer F, Bebelaar D, Voorst JDWV. SPECTRAL PROPERTIES OF (ISO)ALLOXAZINES IN THE VAPOUR PHASE. Photochem Photobiol 1980. [DOI: 10.1111/j.1751-1097.1980.tb03725.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Clarke M, Dowling M, Garafalo A, Brennan T. Structural and electronic effects resulting from metal-flavin ligation. J Biol Chem 1980. [DOI: 10.1016/s0021-9258(19)85723-x] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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Smith WW, Burnett RM, Darling GD, Ludwig ML. Structure of the semiquinone form of flavodoxin from Clostridum MP. Extension of 1.8 A resolution and some comparisons with the oxidized state. J Mol Biol 1977; 117:195-225. [PMID: 599565 DOI: 10.1016/0022-2836(77)90031-6] [Citation(s) in RCA: 191] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Porter DJ, Bright HJ, Voet D. X-ray structures of two oxidation states of a flavin-nicotinamide biscoenzyme and models for flavin--nicotinamide interactions. Nature 1977; 269:213-7. [PMID: 145544 DOI: 10.1038/269213a0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The flavin nicotinamide biscoenzymes Flox(-)--C3--Nic+ and H2Flred--C3--Nic+ assume extended conformations in the solid state. In both derivatives the nicotinamide and flavin groups associate through hydrogen bonding. The bending angle of the reduced flavin moiety is less than half that in any previously reported 1,5-dihydroflavin structure. This effect is apparently due to ring stacking interactions.
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