1
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Sension RJ, McClain TP, Lamb RM, Alonso-Mori R, Lima FA, Ardana-Lamas F, Biednov M, Chollet M, Chung T, Deb A, Dewan PA, Gee LB, Huang Ze En J, Jiang Y, Khakhulin D, Li J, Michocki LB, Miller NA, Otte F, Uemura Y, van Driel TB, Penner-Hahn JE. Watching Excited State Dynamics with Optical and X-ray Probes: The Excited State Dynamics of Aquocobalamin and Hydroxocobalamin. J Am Chem Soc 2023. [PMID: 37327324 DOI: 10.1021/jacs.3c04099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Femtosecond time-resolved X-ray absorption (XANES) at the Co K-edge, X-ray emission (XES) in the Co Kβ and valence-to-core regions, and broadband UV-vis transient absorption are combined to probe the femtosecond to picosecond sequential atomic and electronic dynamics following photoexcitation of two vitamin B12 compounds, hydroxocobalamin and aquocobalamin. Polarized XANES difference spectra allow identification of sequential structural evolution involving first the equatorial and then the axial ligands, with the latter showing rapid coherent bond elongation to the outer turning point of the excited state potential followed by recoil to a relaxed excited state structure. Time-resolved XES, especially in the valence-to-core region, along with polarized optical transient absorption suggests that the recoil results in the formation of a metal-centered excited state with a lifetime of 2-5 ps. This combination of methods provides a uniquely powerful tool to probe the electronic and structural dynamics of photoactive transition-metal complexes and will be applicable to a wide variety of systems.
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Affiliation(s)
- Roseanne J Sension
- Department of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 48109-1055, United States
- Department of Physics, University of Michigan, 450 Church Street, Ann Arbor, Michigan 48109-1040, United States
| | - Taylor P McClain
- Department of Biophysics, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 48109-1055, United States
| | - Ryan M Lamb
- Department of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 48109-1055, United States
| | - Roberto Alonso-Mori
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Frederico Alves Lima
- Femtosecond X-ray Experiments Group, European XFEL, Holzkoppel 4, 22869 Schenefeld, Germany
| | - Fernando Ardana-Lamas
- Femtosecond X-ray Experiments Group, European XFEL, Holzkoppel 4, 22869 Schenefeld, Germany
| | - Mykola Biednov
- Femtosecond X-ray Experiments Group, European XFEL, Holzkoppel 4, 22869 Schenefeld, Germany
| | - Matthieu Chollet
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Taewon Chung
- Department of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 48109-1055, United States
| | - Aniruddha Deb
- Department of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 48109-1055, United States
- Department of Biophysics, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 48109-1055, United States
| | - Paul A Dewan
- Department of Biophysics, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 48109-1055, United States
| | - Leland B Gee
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Joel Huang Ze En
- Department of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 48109-1055, United States
| | - Yifeng Jiang
- Femtosecond X-ray Experiments Group, European XFEL, Holzkoppel 4, 22869 Schenefeld, Germany
| | - Dmitry Khakhulin
- Femtosecond X-ray Experiments Group, European XFEL, Holzkoppel 4, 22869 Schenefeld, Germany
| | - Jianhao Li
- Department of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 48109-1055, United States
| | - Lindsay B Michocki
- Department of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 48109-1055, United States
| | - Nicholas A Miller
- Department of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 48109-1055, United States
| | - Florian Otte
- Femtosecond X-ray Experiments Group, European XFEL, Holzkoppel 4, 22869 Schenefeld, Germany
| | - Yohei Uemura
- Femtosecond X-ray Experiments Group, European XFEL, Holzkoppel 4, 22869 Schenefeld, Germany
| | - Tim B van Driel
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - James E Penner-Hahn
- Department of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 48109-1055, United States
- Department of Biophysics, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 48109-1055, United States
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3
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Hughes JA, Hardman SJO, Lukinović V, Woodward JR, Jones AR. Investigating radical pair reaction dynamics of B 12 coenzymes 1: Transient absorption spectroscopy and magnetic field effects. Methods Enzymol 2022; 669:261-281. [PMID: 35644174 DOI: 10.1016/bs.mie.2021.12.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
B12 coenzymes are vital to healthy biological function across nature. They undergo radical chemistry in a variety of contexts, where spin-correlated radical pairs can be generated both thermally and photochemically. Owing to the unusual magnetic properties of B12 radical pairs, however, most of the reaction and spin dynamics occur on a timescale (picoseconds-nanoseconds) that cannot be resolved by most measurement techniques. Here, we describe a method that combines femtosecond transient absorption spectroscopy with magnetic field exposure, which enables the direct scrutiny of such rapid processes. This approach should provide a means by which to investigate the apparently profound effect protein environments have on the generation and reactivity of B12 radical pairs.
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Affiliation(s)
- Joanna A Hughes
- Laboratory of Ultrafast Spectroscopy, ISIC, and Lausanne Centre for Ultrafast Science (LACUS), École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Samantha J O Hardman
- Manchester Institute of Biotechnology, The University of Manchester, Manchester, United Kingdom
| | | | | | - Alex R Jones
- Biometrology, Department of Chemical and Biological Sciences, National Physical Laboratory, Middlesex, United Kingdom.
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4
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Ghosh AP, Lodowski P, Kozlowski PM. Aerobic photolysis of methylcobalamin: unraveling the photoreaction mechanism. Phys Chem Chem Phys 2022; 24:6093-6106. [PMID: 35212341 DOI: 10.1039/d1cp02013g] [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
The photo-reactivity of cobalamins (Cbls) is influenced by the nature of axial ligands and the cofactor's environment. While the biologically active forms of Cbls with alkyl axial ligands, such as methylcobalamin (MeCbl) and adenosylcobalamin (AdoCbl), are considered to be photolytically active, in contrast, the non-alkyl Cbls are photostable. In addition to these, the photolytic properties of Cbls can also be modulated in the presence of molecular oxygen, i.e., under aerobic conditions. Herein, the photoreaction of the MeCbl in the presence of oxygen has been explored using density functional theory (DFT) and time-dependent DFT (TD-DFT). The first stage of the aerobic photoreaction is the activation of the Co-C bond and the formation of the ligand field (LF) electronic state through the displacement of axial bonds. Once the photoreaction reaches the LF excited state, three processes can occur: namely the formation of OO-CH3 through the reaction of CH3 with molecular oxygen, de-activation of the {Im⋯[CoII(corrin)]⋯CH3}+ sub-system from the LF electronic state by changing the electronic configuration from (dyz)1(dz2)2 to (dyz)2(dz2)1 and the formation of the deactivation complex (DC) complex via the recombination of OO-CH3 species with the de-excited [CoII(corrin)] system. In the proposed mechanism, the deactivation of the [CoII(corrin)] subsystem may coexist with the formation of OO-CH3, followed by immediate relaxation of the subsystems in the ground state. Moreover, the formation of the OO-CH3 species followed by the formation of the {[CoIII(corrin)]-OO-CH3}+ complex stabilizes the system compared to the reactant complex.
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Affiliation(s)
- Arghya Pratim Ghosh
- Department of Chemistry, University of Louisville, Louisville, Kentucky 40292, USA.
| | - Piotr Lodowski
- Institute of Chemistry, University of Silesia in Katowice, Szkolna 9, PL-40 006 Katowice, Poland
| | - Pawel M Kozlowski
- Department of Chemistry, University of Louisville, Louisville, Kentucky 40292, USA.
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5
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Boopalan S, Antony A, Loyid NS, Vijaikanth V, Murugan S. Synthesis, characterization, X-ray crystal structures and antibacterial properties of cobaloximes with aniline based ligands containing acid functionality. INORG NANO-MET CHEM 2022. [DOI: 10.1080/24701556.2021.2025076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- S. Boopalan
- Department of Applied Chemistry, Karunya Institute of Technology and Sciences, Coimbatore, Tamil Nadu, India
| | - Aneesha Antony
- Department of Applied Chemistry, Karunya Institute of Technology and Sciences, Coimbatore, Tamil Nadu, India
| | - Nienu Susan Loyid
- Department of Biotechnology, Karunya Institute of Technology and Sciences, Coimbatore, Tamil Nadu, India
| | - V. Vijaikanth
- Department of Applied Chemistry, Karunya Institute of Technology and Sciences, Coimbatore, Tamil Nadu, India
| | - S. Murugan
- Department of Biotechnology, Karunya Institute of Technology and Sciences, Coimbatore, Tamil Nadu, India
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6
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Ghosh AP, Lodowski P, Bazarganpour A, Leks M, Kozlowski PM. Aerobic photolysis of methylcobalamin: structural and electronic properties of the Cbl-O-O-CH 3 intermediate. Dalton Trans 2020; 49:4114-4124. [PMID: 32142090 DOI: 10.1039/c9dt03740c] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Photolysis of methylcobalamin (MeCbl) in the presence of molecular oxygen (O2) has been investigated using density functional theory (DFT) and time-dependent DFT (TD-DFT). The key step involves the formation of the Cbl-O-O-CH3 intermediate as a result of triplet O2 insertion in the Co-C bond in the presence of light. Analysis of low-lying excited states shows that the presence of light is only needed to activate the Co-C bond via the formation of the ligand field (LF) state. The insertion of O2, as well as the change in the spin state, takes place in the ground state. The analysis of the structural and electronic properties of the Cbl-O-O-CH3 intermediate is presented and possible decomposition also discussed.
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Affiliation(s)
- Arghya Pratim Ghosh
- Department of Chemistry, University of Louisville, Louisville, Kentucky 40292, USA.
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7
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Hughes JA, Hardman SJO, Scrutton NS, Graham DM, Woodward JR, Jones AR. Observation of the Δg mechanism resulting from the ultrafast spin dynamics that follow the photolysis of coenzyme B 12. J Chem Phys 2019; 151:201102. [PMID: 31779325 DOI: 10.1063/1.5127258] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Throughout nature, both free radicals and transient radical reaction intermediates are vital to many biological functions. Coenzyme B12 is a case in point. This organometallic cofactor generates a radical pair upon activation in its dependent enzymes by substrate binding and following photolysis. The resulting cob(ii)alamin/5'-deoxyadenosyl radical pair has unusual magnetic properties that present a challenge to detailed investigation at ambient temperatures. Here, we use femtosecond transient absorption spectroscopy adapted for magnetic field exposure to reveal that the spin dynamics of the B12 radical pair are sufficiently fast for magnetic field effects to be observed on the ultrafast reaction kinetics. Moreover, the large difference in g-values between the radicals of the pair means that effects of the Δg mechanism are observed for the first time for a radical pair system exposed to magnetic fields below 1 T. Spin dynamic simulations allow a value of the cob(ii)alamin radical g-value (2.105) at ambient temperature to be extracted and, because the spin dynamic time scale is faster than the diffusional rotation of the cob(ii)alamin radical, the observed value corresponds to the anisotropic g|| value for this radical.
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Affiliation(s)
- Joanna A Hughes
- Manchester Institute of Biotechnology and Department of Chemistry, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Samantha J O Hardman
- Manchester Institute of Biotechnology and Department of Chemistry, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Nigel S Scrutton
- Manchester Institute of Biotechnology and Department of Chemistry, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Darren M Graham
- Photon Science Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Jonathan R Woodward
- Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Japan
| | - Alex R Jones
- Manchester Institute of Biotechnology and Department of Chemistry, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
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