1
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Austvold CK, Keable SM, Procopio M, Usselman RJ. Quantitative measurements of reactive oxygen species partitioning in electron transfer flavoenzyme magnetic field sensing. Front Physiol 2024; 15:1348395. [PMID: 38370016 PMCID: PMC10869518 DOI: 10.3389/fphys.2024.1348395] [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: 12/02/2023] [Accepted: 01/16/2024] [Indexed: 02/20/2024] Open
Abstract
Biological magnetic field sensing that gives rise to physiological responses is of considerable importance in quantum biology. The radical pair mechanism (RPM) is a fundamental quantum process that can explain some of the observed biological magnetic effects. In magnetically sensitive radical pair (RP) reactions, coherent spin dynamics between singlet and triplet pairs are modulated by weak magnetic fields. The resulting singlet and triplet reaction products lead to distinct biological signaling channels and cellular outcomes. A prevalent RP in biology is between flavin semiquinone and superoxide (O2 •-) in the biological activation of molecular oxygen. This RP can result in a partitioning of reactive oxygen species (ROS) products to form either O2 •- or hydrogen peroxide (H2O2). Here, we examine magnetic sensing of recombinant human electron transfer flavoenzyme (ETF) reoxidation by selectively measuring O2 •- and H2O2 product distributions. ROS partitioning was observed between two static magnetic fields at 20 nT and 50 μT, with a 13% decrease in H2O2 singlet products and a 10% increase in O2 •- triplet products relative to 50 µT. RPM product yields were calculated for a realistic flavin/superoxide RP across the range of static magnetic fields, in agreement with experimental results. For a triplet born RP, the RPM also predicts about three times more O2 •- than H2O2, with experimental results exhibiting about four time more O2 •- produced by ETF. The method presented here illustrates the potential of a novel magnetic flavoprotein biological sensor that is directly linked to mitochondria bioenergetics and can be used as a target to study cell physiology.
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Affiliation(s)
- Chase K. Austvold
- Chemistry and Biochemistry, Montana State University, Bozeman, MT, United States
| | - Stephen M. Keable
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, United States
| | - Maria Procopio
- Biophysics, Johns Hopkins University, Baltimore, MD, United States
| | - Robert J. Usselman
- Chemistry and Chemical Engineering, Florida Institute of Technology, Melbourne, FL, United States
- Computational Research At Florida Tech, Melbourne, FL, United States
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2
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Uzhytchak M, Smolková B, Frtús A, Stupakov A, Lunova M, Scollo F, Hof M, Jurkiewicz P, Sullivan GJ, Dejneka A, Lunov O. Sensitivity of endogenous autofluorescence in HeLa cells to the application of external magnetic fields. Sci Rep 2023; 13:10818. [PMID: 37402779 DOI: 10.1038/s41598-023-38015-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Accepted: 06/30/2023] [Indexed: 07/06/2023] Open
Abstract
Dramatically increased levels of electromagnetic radiation in the environment have raised concerns over the potential health hazards of electromagnetic fields. Various biological effects of magnetic fields have been proposed. Despite decades of intensive research, the molecular mechanisms procuring cellular responses remain largely unknown. The current literature is conflicting with regards to evidence that magnetic fields affect functionality directly at the cellular level. Therefore, a search for potential direct cellular effects of magnetic fields represents a cornerstone that may propose an explanation for potential health hazards associated with magnetic fields. It has been proposed that autofluorescence of HeLa cells is magnetic field sensitive, relying on single-cell imaging kinetic measurements. Here, we investigate the magnetic field sensitivity of an endogenous autofluorescence in HeLa cells. Under the experimental conditions used, magnetic field sensitivity of an endogenous autofluorescence was not observed in HeLa cells. We present a number of arguments indicating why this is the case in the analysis of magnetic field effects based on the imaging of cellular autofluorescence decay. Our work indicates that new methods are required to elucidate the effects of magnetic fields at the cellular level.
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Affiliation(s)
- Mariia Uzhytchak
- Department of Optical and Biophysical Systems, Institute of Physics of the Czech Academy of Sciences, Prague, 18221, Czech Republic
| | - Barbora Smolková
- Department of Optical and Biophysical Systems, Institute of Physics of the Czech Academy of Sciences, Prague, 18221, Czech Republic
| | - Adam Frtús
- Department of Optical and Biophysical Systems, Institute of Physics of the Czech Academy of Sciences, Prague, 18221, Czech Republic
| | - Alexandr Stupakov
- Department of Optical and Biophysical Systems, Institute of Physics of the Czech Academy of Sciences, Prague, 18221, Czech Republic
| | - Mariia Lunova
- Department of Optical and Biophysical Systems, Institute of Physics of the Czech Academy of Sciences, Prague, 18221, Czech Republic
- Institute for Clinical and Experimental Medicine (IKEM), Prague, 14021, Czech Republic
| | - Federica Scollo
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Prague, 18223, Czech Republic
| | - Martin Hof
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Prague, 18223, Czech Republic
| | - Piotr Jurkiewicz
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Prague, 18223, Czech Republic
| | - Gareth John Sullivan
- Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
- Department of Pediatric Research, Oslo University Hospital, Oslo, Norway
- Department of Immunology, Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Alexandr Dejneka
- Department of Optical and Biophysical Systems, Institute of Physics of the Czech Academy of Sciences, Prague, 18221, Czech Republic
| | - Oleg Lunov
- Department of Optical and Biophysical Systems, Institute of Physics of the Czech Academy of Sciences, Prague, 18221, Czech Republic.
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3
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Abstract
We demonstrate, by direct, single-cell imaging kinetic measurements, that endogenous autofluorescence in HeLa cells is sensitive to the application of external magnetic fields of 25 mT and less. We provide spectroscopic and mechanistic evidence that our findings can be explained in terms of magnetic field effects on photoinduced electron transfer reactions to flavins, through the radical pair mechanism. The observed magnetic field dependence is consistent with a triplet-born radical pair and a B1/2 value of 18.0 mT with a saturation value of 3.7%.
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4
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Déjean V, Konowalczyk M, Gravell J, Golesworthy MJ, Gunn C, Pompe N, Foster Vander Elst O, Tan KJ, Oxborrow M, Aarts DGAL, Mackenzie SR, Timmel CR. Detection of magnetic field effects by confocal microscopy. Chem Sci 2020; 11:7772-7781. [PMID: 34094150 PMCID: PMC8163210 DOI: 10.1039/d0sc01986k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Certain pairs of paramagnetic species generated under conservation of total spin angular momentum are known to undergo magnetosensitive processes. Two prominent examples of systems exhibiting these so-called magnetic field effects (MFEs) are photogenerated radical pairs created from either singlet or triplet molecular precursors, and pairs of triplet states generated by singlet fission. Here, we showcase confocal microscopy as a powerful technique for the investigation of such phenomena. We first characterise the instrument by studying the field-sensitive chemistry of two systems in solution: radical pairs formed in a cryptochrome protein and the flavin mononucleotide/hen egg-white lysozyme model system. We then extend these studies to single crystals. Firstly, we report temporally and spatially resolved MFEs in flavin-doped lysozyme single crystals. Anisotropic magnetic field effects are then reported in tetracene single crystals. Finally, we discuss the future applications of confocal microscopy for the study of magnetosensitive processes with a particular focus on the cryptochrome-based chemical compass believed to lie at the heart of animal magnetoreception. Confocal microscopy is showcased as a powerful technique for the measurement of spatiotemporally-resolved magnetic field effects in both solutions and single crystals.![]()
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Affiliation(s)
- Victoire Déjean
- Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory Oxford OX1 3QR UK
| | - Marcin Konowalczyk
- Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory Oxford OX1 3QR UK .,Department of Chemistry, University of Oxford, Physical and Theoretical Chemistry Laboratory Oxford OX1 3QZ UK
| | - Jamie Gravell
- Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory Oxford OX1 3QR UK
| | - Matthew J Golesworthy
- Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory Oxford OX1 3QR UK
| | - Catlin Gunn
- Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory Oxford OX1 3QR UK
| | - Nils Pompe
- Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory Oxford OX1 3QR UK
| | | | - Ke-Jie Tan
- Department of Materials, Imperial College London London SW7 2AZ UK
| | - Mark Oxborrow
- Department of Materials, Imperial College London London SW7 2AZ UK
| | - Dirk G A L Aarts
- Department of Chemistry, University of Oxford, Physical and Theoretical Chemistry Laboratory Oxford OX1 3QZ UK
| | - Stuart R Mackenzie
- Department of Chemistry, University of Oxford, Physical and Theoretical Chemistry Laboratory Oxford OX1 3QZ UK
| | - Christiane R Timmel
- Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory Oxford OX1 3QR UK .,Centre for Advanced Electron Spin Resonance (CAESR), Department of Chemistry, University of Oxford Oxford OX1 3QR UK
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5
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Pooam M, Arthaut LD, Burdick D, Link J, Martino CF, Ahmad M. Magnetic sensitivity mediated by the Arabidopsis blue-light receptor cryptochrome occurs during flavin reoxidation in the dark. PLANTA 2019; 249:319-332. [PMID: 30194534 DOI: 10.1007/s00425-018-3002-y] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 08/29/2018] [Indexed: 05/20/2023]
Abstract
Arabidopsis cryptochrome mediates responses to magnetic fields that have been applied in the absence of light, consistent with flavin reoxidation as the primary detection mechanism. Cryptochromes are highly conserved blue-light-absorbing flavoproteins which have been linked to the perception of electromagnetic stimuli in numerous organisms. These include sensing the direction of the earth's magnetic field in migratory birds and the intensity of magnetic fields in insects and plants. When exposed to light, cryptochromes undergo flavin reduction/reoxidation redox cycles leading to biological activation which generate radical pairs thought to be the basis for magnetic sensitivity. However, the nature of the magnetically sensitive radical pairs and the steps at which they act during the cryptochrome redox cycle are currently a matter of debate. Here, we investigate the response of Arabidopsis cryptochrome-1 in vivo to a static magnetic field of 500 μT (10 × earth's field) using both plant growth and light-dependent phosphorylation as an assay. Cryptochrome responses to light were enhanced by the magnetic field, as indicated by increased inhibition of hypocotyl elongation and increased cryptochrome phosphorylation. However, when light and dark intervals were given intermittently, a plant response to the magnetic field was observed even when the magnetic field was given exclusively during the dark intervals between light exposures. This indicates that the magnetically sensitive reaction step in the cryptochrome photocycle must occur during flavin reoxidation, and likely involves the formation of reactive oxygen species.
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Affiliation(s)
- Marootpong Pooam
- Sorbonne Universités, CNRS, UMR8256, IBPS, Photobiology Research Group, 7 Quai St. Bernard, 75005, Paris, France
| | - Louis-David Arthaut
- Sorbonne Universités, CNRS, UMR8256, IBPS, Photobiology Research Group, 7 Quai St. Bernard, 75005, Paris, France
| | - Derek Burdick
- Sorbonne Universités, CNRS, UMR8256, IBPS, Photobiology Research Group, 7 Quai St. Bernard, 75005, Paris, France
- Xavier University, 3800 Victory Parkway, Cincinnati, OH, 45207, USA
| | - Justin Link
- Xavier University, 3800 Victory Parkway, Cincinnati, OH, 45207, USA
| | - Carlos F Martino
- Department of Biomedical Engineering, Florida Institute of Technology, 150W University Blvd, Melbourne, FL, 32901, USA
| | - Margaret Ahmad
- Sorbonne Universités, CNRS, UMR8256, IBPS, Photobiology Research Group, 7 Quai St. Bernard, 75005, Paris, France.
- Xavier University, 3800 Victory Parkway, Cincinnati, OH, 45207, USA.
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6
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Sannikova VA, Davydova MP, Sherin PS, Babenko SV, Korolev VV, Stepanov AA, Nikul'shin PV, Kalneus EV, Vasilevsky SF, Benassi E, Melnikov AR. Determination of Hyperfine Coupling Constants of Fluorinated Diphenylacetylene Radical Anions by Magnetic Field-Affected Reaction Yield Spectroscopy. J Phys Chem A 2019; 123:505-516. [PMID: 30566354 DOI: 10.1021/acs.jpca.8b10306] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Magnetic field-affected reaction yield (MARY) spectroscopy is a spin chemistry technique for detecting short-lived radical ions. Having sensitivity to transient species with lifetimes as short as nanoseconds, MARY spectroscopy usually does not provide detailed information on their magnetic resonance parameters, except for simple systems with equivalent magnetic nuclei. In this work, the radical anions of two fluorinated diphenylacetylene derivatives with nonequivalent magnetic nuclei and unknown hyperfine coupling constants ( AHF) were investigated by MARY spectroscopy. The MARY spectra were found to be resolved and have resonance lines in nonzero magnetic fields, which are determined by the AHF values. Simple relationships between the positions of resonance MARY lines and the AHF values were established from the analysis of the different Hamiltonian block contributions to the MARY spectrum. The obtained experimental AHF values are in agreement with the results of quantum chemical calculations at the density functional theory level.
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Affiliation(s)
- Victoria A Sannikova
- Institute of Chemical Kinetics and Combustion SB RAS , 3, Institutskaya Str. , 630090 Novosibirsk , Russian Federation.,Novosibirsk State University , 2, Pirogova Str. , 630090 Novosibirsk , Russian Federation
| | - Maria P Davydova
- Institute of Chemical Kinetics and Combustion SB RAS , 3, Institutskaya Str. , 630090 Novosibirsk , Russian Federation.,A.V. Nikolaev Institute of Inorganic Chemistry SB RAS , 3, Akademika Lavrentieva Ave. , 630090 Novosibirsk , Russian Federation
| | - Peter S Sherin
- Novosibirsk State University , 2, Pirogova Str. , 630090 Novosibirsk , Russian Federation.,International Tomography Center , 3a, Institutskaya Str. , 630090 Novosibirsk , Russian Federation
| | - Simon V Babenko
- Institute of Chemical Kinetics and Combustion SB RAS , 3, Institutskaya Str. , 630090 Novosibirsk , Russian Federation
| | - Valeri V Korolev
- Institute of Chemical Kinetics and Combustion SB RAS , 3, Institutskaya Str. , 630090 Novosibirsk , Russian Federation
| | - Alexander A Stepanov
- Institute of Chemical Kinetics and Combustion SB RAS , 3, Institutskaya Str. , 630090 Novosibirsk , Russian Federation.,Novosibirsk State University , 2, Pirogova Str. , 630090 Novosibirsk , Russian Federation
| | - Pavel V Nikul'shin
- N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry SB RAS , 9, Akademika Lavrentieva Ave. , 630090 Novosibirsk , Russian Federation
| | - Evgeny V Kalneus
- Institute of Chemical Kinetics and Combustion SB RAS , 3, Institutskaya Str. , 630090 Novosibirsk , Russian Federation
| | - Sergei F Vasilevsky
- Institute of Chemical Kinetics and Combustion SB RAS , 3, Institutskaya Str. , 630090 Novosibirsk , Russian Federation.,Novosibirsk State University , 2, Pirogova Str. , 630090 Novosibirsk , Russian Federation
| | - Enrico Benassi
- Novosibirsk State University , 2, Pirogova Str. , 630090 Novosibirsk , Russian Federation.,Department of Chemistry , Hexi University , 734000 Zhangye , China
| | - Anatoly R Melnikov
- Institute of Chemical Kinetics and Combustion SB RAS , 3, Institutskaya Str. , 630090 Novosibirsk , Russian Federation.,Novosibirsk State University , 2, Pirogova Str. , 630090 Novosibirsk , Russian Federation
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7
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Zollitsch TM, Jarocha LE, Bialas C, Henbest KB, Kodali G, Dutton PL, Moser CC, Timmel CR, Hore PJ, Mackenzie SR. Magnetically Sensitive Radical Photochemistry of Non-natural Flavoproteins. J Am Chem Soc 2018; 140:8705-8713. [PMID: 29940116 DOI: 10.1021/jacs.8b03104] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
It is a remarkable fact that ∼50 μT magnetic fields can alter the rates and yields of certain free-radical reactions and that such effects might be the basis of the light-dependent ability of migratory birds to sense the direction of the Earth's magnetic field. The most likely sensory molecule at the heart of this chemical compass is cryptochrome, a flavin-containing protein that undergoes intramolecular, blue-light-induced electron transfer to produce magnetically sensitive radical pairs. To learn more about the factors that control the magnetic sensitivity of cryptochromes, we have used a set of de novo designed protein maquettes that self-assemble as four-α-helical proteins incorporating a single tryptophan residue as an electron donor placed approximately 0.6, 1.1, or 1.7 nm away from a covalently attached riboflavin as chromophore and electron acceptor. Using a specifically developed form of cavity ring-down spectroscopy, we have characterized the photochemistry of these designed flavoprotein maquettes to determine the identities and kinetics of the transient radicals responsible for the magnetic field effects. Given the gross structural and dynamic differences from the natural proteins, it is remarkable that the maquettes show magnetic field effects that are so similar to those observed for cryptochromes.
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Affiliation(s)
- Tilo M Zollitsch
- Department of Chemistry , University of Oxford, Physical and Theoretical Chemistry Laboratory , Oxford OX1 3QZ , United Kingdom
| | - Lauren E Jarocha
- Department of Chemistry , University of Oxford, Physical and Theoretical Chemistry Laboratory , Oxford OX1 3QZ , United Kingdom
| | - Chris Bialas
- Johnson Research Foundation, Department of Biochemistry and Biophysics , University of Pennsylvania , Philadelphia , Pennsylvania 19104 , United States
| | - Kevin B Henbest
- Department of Chemistry , University of Oxford, Centre for Advanced Electron Spin Resonance, Inorganic Chemistry Laboratory , Oxford OX1 3QR , United Kingdom
| | - Goutham Kodali
- Johnson Research Foundation, Department of Biochemistry and Biophysics , University of Pennsylvania , Philadelphia , Pennsylvania 19104 , United States
| | - P Leslie Dutton
- Johnson Research Foundation, Department of Biochemistry and Biophysics , University of Pennsylvania , Philadelphia , Pennsylvania 19104 , United States
| | - Christopher C Moser
- Johnson Research Foundation, Department of Biochemistry and Biophysics , University of Pennsylvania , Philadelphia , Pennsylvania 19104 , United States
| | - Christiane R Timmel
- Department of Chemistry , University of Oxford, Centre for Advanced Electron Spin Resonance, Inorganic Chemistry Laboratory , Oxford OX1 3QR , United Kingdom
| | - P J Hore
- Department of Chemistry , University of Oxford, Physical and Theoretical Chemistry Laboratory , Oxford OX1 3QZ , United Kingdom
| | - Stuart R Mackenzie
- Department of Chemistry , University of Oxford, Physical and Theoretical Chemistry Laboratory , Oxford OX1 3QZ , United Kingdom
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8
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Paul S, Meng L, Berger S, Grampp G, Matysik J, Wang X. The Flavin-Tryptophan Dyad F10T as a Cryptochrome Model Compound: Synthesis and Photochemistry. CHEMPHOTOCHEM 2016. [DOI: 10.1002/cptc.201600025] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Shubhajit Paul
- Institut für Analytische Chemie; Universität Leipzig; Linnéstr. 3 04103 Leipzig Germany
| | - Lingqiang Meng
- Department of Chemistry and Biology; National University of Defense Technology; 410073 Changsha China
- Yanching Institute of Technology; 065200, Sanhe, Hebei China
| | - Stefan Berger
- Institut für Analytische Chemie; Universität Leipzig; Linnéstr. 3 04103 Leipzig Germany
| | - Günter Grampp
- Institut für Physikalische und Theoretische Chemie; Technische Universität Graz; Streymayrgasse 9/I 8010 Graz Austria
| | - Jörg Matysik
- Institut für Analytische Chemie; Universität Leipzig; Linnéstr. 3 04103 Leipzig Germany
| | - Xiaojie Wang
- Department of Chemistry and Biology; National University of Defense Technology; 410073 Changsha China
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9
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Evans EW, Kattnig DR, Henbest KB, Hore PJ, Mackenzie SR, Timmel CR. Sub-millitesla magnetic field effects on the recombination reaction of flavin and ascorbic acid radicals. J Chem Phys 2016; 145:085101. [DOI: 10.1063/1.4961266] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Emrys W. Evans
- Department of Chemistry, Centre for Advanced Electron Spin Resonance, University of Oxford, Oxford, United Kingdom
| | - Daniel R. Kattnig
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, Oxford, United Kingdom
| | - Kevin B. Henbest
- Department of Chemistry, Centre for Advanced Electron Spin Resonance, University of Oxford, Oxford, United Kingdom
| | - P. J. Hore
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, Oxford, United Kingdom
| | - Stuart R. Mackenzie
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, Oxford, United Kingdom
| | - Christiane R. Timmel
- Department of Chemistry, Centre for Advanced Electron Spin Resonance, University of Oxford, Oxford, United Kingdom
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10
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Worster S, Kattnig DR, Hore PJ. Spin relaxation of radicals in cryptochrome and its role in avian magnetoreception. J Chem Phys 2016; 145:035104. [DOI: 10.1063/1.4958624] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Affiliation(s)
- Susannah Worster
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
| | - Daniel R. Kattnig
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
| | - P. J. Hore
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
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11
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Kattnig DR, Evans EW, Déjean V, Dodson CA, Wallace MI, Mackenzie SR, Timmel CR, Hore PJ. Chemical amplification of magnetic field effects relevant to avian magnetoreception. Nat Chem 2016; 8:384-91. [PMID: 27001735 DOI: 10.1038/nchem.2447] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Accepted: 12/18/2015] [Indexed: 12/15/2022]
Abstract
Magnetic fields as weak as the Earth's can change the yields of radical pair reactions even though the energies involved are orders of magnitude smaller than the thermal energy, kBT, at room temperature. Proposed as the source of the light-dependent magnetic compass in migratory birds, the radical pair mechanism is thought to operate in cryptochrome flavoproteins in the retina. Here we demonstrate that the primary magnetic field effect on flavin photoreactions can be amplified chemically by slow radical termination reactions under conditions of continuous photoexcitation. The nature and origin of the amplification are revealed by studies of the intermolecular flavin-tryptophan and flavin-ascorbic acid photocycles and the closely related intramolecular flavin-tryptophan radical pair in cryptochrome. Amplification factors of up to 5.6 were observed for magnetic fields weaker than 1 mT. Substantial chemical amplification could have a significant impact on the viability of a cryptochrome-based magnetic compass sensor.
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Affiliation(s)
- Daniel R Kattnig
- Department of Chemistry, University of Oxford, Physical &Theoretical Chemistry Laboratory, Oxford OX1 3QZ, UK
| | - Emrys W Evans
- Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, Oxford OX1 3QR, UK
| | - Victoire Déjean
- Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, Oxford OX1 3QR, UK
| | - Charlotte A Dodson
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Oxford OX1 3TA, UK
| | - Mark I Wallace
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Oxford OX1 3TA, UK
| | - Stuart R Mackenzie
- Department of Chemistry, University of Oxford, Physical &Theoretical Chemistry Laboratory, Oxford OX1 3QZ, UK
| | - Christiane R Timmel
- Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, Oxford OX1 3QR, UK
| | - P J Hore
- Department of Chemistry, University of Oxford, Physical &Theoretical Chemistry Laboratory, Oxford OX1 3QZ, UK
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