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1
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Sension RJ, McClain TP, Michocki LB, Miller NA, Alonso-Mori R, Lima FA, Ardana-Lamas F, Biednov M, Chung T, Deb A, Jiang Y, Kaneshiro AK, Khakhulin D, Kubarych KJ, Lamb RM, Meadows JH, Otte F, Sofferman DL, Song S, Uemura Y, van Driel TB, Penner-Hahn JE. Structural Evolution of Photoexcited Methylcobalamin toward a CarH-like Metastable State: Evidence from Time-Resolved X-ray Absorption and X-ray Emission. J Phys Chem B 2024; 128:8131-8144. [PMID: 39150518 DOI: 10.1021/acs.jpcb.4c03729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/17/2024]
Abstract
CarH is a protein photoreceptor that uses a form of B12, adenosylcobalamin (AdoCbl), to sense light via formation of a metastable excited state. Aside from AdoCbl bound to CarH, methylcobalamin (MeCbl) is the only other example─to date─of photoexcited cobalamins forming metastable excited states with lifetimes of nanoseconds or longer. The UV-visible spectra of the excited states of MeCbl and AdoCbl bound to CarH are similar. We have used transient Co K-edge X-ray absorption and X-ray emission spectroscopies in conjunction with transient absorption spectroscopy in the UV-visible region to characterize the excited states of MeCbl. These data show that the metastable excited state of MeCbl has a slightly expanded corrin ring and increased electron density on the cobalt, but only small changes in the axial bond lengths.
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Affiliation(s)
- Roseanne J Sension
- Department of Chemistry, University of Michigan, 930 N University Ave. 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
- Biophysics, University of Michigan, 930 N University Ave. Ann Arbor, Michigan 48109-1055, United States
| | - Lindsay B Michocki
- Department of Chemistry, University of Michigan, 930 N University Ave. Ann Arbor, Michigan 48109-1055, United States
| | - Nicholas A Miller
- Department of Chemistry, University of Michigan, 930 N University Ave. 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
| | - Taewon Chung
- Department of Chemistry, University of Michigan, 930 N University Ave. Ann Arbor, Michigan 48109-1055, United States
| | - Aniruddha Deb
- Department of Chemistry, University of Michigan, 930 N University Ave. Ann Arbor, Michigan 48109-1055, United States
| | - Yifeng Jiang
- Femtosecond X-ray Experiments Group, European XFEL, Holzkoppel 4, 22869 Schenefeld, Germany
| | - April K Kaneshiro
- Department of Biological Chemistry, 1150 W. Medical Center Dr., Ann Arbor, Michigan 48109-0600, United States
| | - Dmitry Khakhulin
- Femtosecond X-ray Experiments Group, European XFEL, Holzkoppel 4, 22869 Schenefeld, Germany
| | - Kevin J Kubarych
- Department of Chemistry, University of Michigan, 930 N University Ave. Ann Arbor, Michigan 48109-1055, United States
| | - Ryan M Lamb
- Department of Chemistry, University of Michigan, 930 N University Ave. Ann Arbor, Michigan 48109-1055, United States
| | - Joseph H Meadows
- Department of Chemistry, University of Michigan, 930 N University Ave. Ann Arbor, Michigan 48109-1055, United States
| | - Florian Otte
- Femtosecond X-ray Experiments Group, European XFEL, Holzkoppel 4, 22869 Schenefeld, Germany
| | - Danielle L Sofferman
- Program in Applied Physics, University of Michigan, 450 Church Street, Ann Arbor, Michigan 48109-1040, United States
| | - Sanghoon Song
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - 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 Ave. Ann Arbor, Michigan 48109-1055, United States
- Biophysics, University of Michigan, 930 N University Ave. Ann Arbor, Michigan 48109-1055, United States
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Antolini C, Sosa Alfaro V, Reinhard M, Chatterjee G, Ribson R, Sokaras D, Gee L, Sato T, Kramer PL, Raj SL, Hayes B, Schleissner P, Garcia-Esparza AT, Lim J, Babicz JT, Follmer AH, Nelson S, Chollet M, Alonso-Mori R, van Driel TB. The Liquid Jet Endstation for Hard X-ray Scattering and Spectroscopy at the Linac Coherent Light Source. Molecules 2024; 29:2323. [PMID: 38792184 PMCID: PMC11124266 DOI: 10.3390/molecules29102323] [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: 04/10/2024] [Revised: 05/10/2024] [Accepted: 05/13/2024] [Indexed: 05/26/2024] Open
Abstract
The ability to study chemical dynamics on ultrafast timescales has greatly advanced with the introduction of X-ray free electron lasers (XFELs) providing short pulses of intense X-rays tailored to probe atomic structure and electronic configuration. Fully exploiting the full potential of XFELs requires specialized experimental endstations along with the development of techniques and methods to successfully carry out experiments. The liquid jet endstation (LJE) at the Linac Coherent Light Source (LCLS) has been developed to study photochemistry and biochemistry in solution systems using a combination of X-ray solution scattering (XSS), X-ray absorption spectroscopy (XAS), and X-ray emission spectroscopy (XES). The pump-probe setup utilizes an optical laser to excite the sample, which is subsequently probed by a hard X-ray pulse to resolve structural and electronic dynamics at their intrinsic femtosecond timescales. The LJE ensures reliable sample delivery to the X-ray interaction point via various liquid jets, enabling rapid replenishment of thin samples with millimolar concentrations and low sample volumes at the 120 Hz repetition rate of the LCLS beam. This paper provides a detailed description of the LJE design and of the techniques it enables, with an emphasis on the diagnostics required for real-time monitoring of the liquid jet and on the spatiotemporal overlap methods used to optimize the signal. Additionally, various scientific examples are discussed, highlighting the versatility of the LJE.
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Affiliation(s)
- Cali Antolini
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA; (C.A.); (V.S.A.); (M.R.); (G.C.); (R.R.); (D.S.); (L.G.); (T.S.); (P.L.K.); (S.L.R.); (B.H.); (P.S.); (A.T.G.-E.); (J.L.); (J.T.B.J.); (S.N.); (M.C.)
| | - Victor Sosa Alfaro
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA; (C.A.); (V.S.A.); (M.R.); (G.C.); (R.R.); (D.S.); (L.G.); (T.S.); (P.L.K.); (S.L.R.); (B.H.); (P.S.); (A.T.G.-E.); (J.L.); (J.T.B.J.); (S.N.); (M.C.)
| | - Marco Reinhard
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA; (C.A.); (V.S.A.); (M.R.); (G.C.); (R.R.); (D.S.); (L.G.); (T.S.); (P.L.K.); (S.L.R.); (B.H.); (P.S.); (A.T.G.-E.); (J.L.); (J.T.B.J.); (S.N.); (M.C.)
| | - Gourab Chatterjee
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA; (C.A.); (V.S.A.); (M.R.); (G.C.); (R.R.); (D.S.); (L.G.); (T.S.); (P.L.K.); (S.L.R.); (B.H.); (P.S.); (A.T.G.-E.); (J.L.); (J.T.B.J.); (S.N.); (M.C.)
| | - Ryan Ribson
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA; (C.A.); (V.S.A.); (M.R.); (G.C.); (R.R.); (D.S.); (L.G.); (T.S.); (P.L.K.); (S.L.R.); (B.H.); (P.S.); (A.T.G.-E.); (J.L.); (J.T.B.J.); (S.N.); (M.C.)
| | - Dimosthenis Sokaras
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA; (C.A.); (V.S.A.); (M.R.); (G.C.); (R.R.); (D.S.); (L.G.); (T.S.); (P.L.K.); (S.L.R.); (B.H.); (P.S.); (A.T.G.-E.); (J.L.); (J.T.B.J.); (S.N.); (M.C.)
| | - Leland Gee
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA; (C.A.); (V.S.A.); (M.R.); (G.C.); (R.R.); (D.S.); (L.G.); (T.S.); (P.L.K.); (S.L.R.); (B.H.); (P.S.); (A.T.G.-E.); (J.L.); (J.T.B.J.); (S.N.); (M.C.)
| | - Takahiro Sato
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA; (C.A.); (V.S.A.); (M.R.); (G.C.); (R.R.); (D.S.); (L.G.); (T.S.); (P.L.K.); (S.L.R.); (B.H.); (P.S.); (A.T.G.-E.); (J.L.); (J.T.B.J.); (S.N.); (M.C.)
| | - Patrick L. Kramer
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA; (C.A.); (V.S.A.); (M.R.); (G.C.); (R.R.); (D.S.); (L.G.); (T.S.); (P.L.K.); (S.L.R.); (B.H.); (P.S.); (A.T.G.-E.); (J.L.); (J.T.B.J.); (S.N.); (M.C.)
| | - Sumana Laxmi Raj
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA; (C.A.); (V.S.A.); (M.R.); (G.C.); (R.R.); (D.S.); (L.G.); (T.S.); (P.L.K.); (S.L.R.); (B.H.); (P.S.); (A.T.G.-E.); (J.L.); (J.T.B.J.); (S.N.); (M.C.)
| | - Brandon Hayes
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA; (C.A.); (V.S.A.); (M.R.); (G.C.); (R.R.); (D.S.); (L.G.); (T.S.); (P.L.K.); (S.L.R.); (B.H.); (P.S.); (A.T.G.-E.); (J.L.); (J.T.B.J.); (S.N.); (M.C.)
| | - Pamela Schleissner
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA; (C.A.); (V.S.A.); (M.R.); (G.C.); (R.R.); (D.S.); (L.G.); (T.S.); (P.L.K.); (S.L.R.); (B.H.); (P.S.); (A.T.G.-E.); (J.L.); (J.T.B.J.); (S.N.); (M.C.)
| | - Angel T. Garcia-Esparza
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA; (C.A.); (V.S.A.); (M.R.); (G.C.); (R.R.); (D.S.); (L.G.); (T.S.); (P.L.K.); (S.L.R.); (B.H.); (P.S.); (A.T.G.-E.); (J.L.); (J.T.B.J.); (S.N.); (M.C.)
| | - Jinkyu Lim
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA; (C.A.); (V.S.A.); (M.R.); (G.C.); (R.R.); (D.S.); (L.G.); (T.S.); (P.L.K.); (S.L.R.); (B.H.); (P.S.); (A.T.G.-E.); (J.L.); (J.T.B.J.); (S.N.); (M.C.)
- Department of Energy and Environmental Engineering, The Catholic University of Korea, Bucheon 14662, Republic of Korea
| | - Jeffrey T. Babicz
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA; (C.A.); (V.S.A.); (M.R.); (G.C.); (R.R.); (D.S.); (L.G.); (T.S.); (P.L.K.); (S.L.R.); (B.H.); (P.S.); (A.T.G.-E.); (J.L.); (J.T.B.J.); (S.N.); (M.C.)
| | - Alec H. Follmer
- Department of Chemistry, University of California-Irvine, Irvine, CA 92697, USA;
| | - Silke Nelson
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA; (C.A.); (V.S.A.); (M.R.); (G.C.); (R.R.); (D.S.); (L.G.); (T.S.); (P.L.K.); (S.L.R.); (B.H.); (P.S.); (A.T.G.-E.); (J.L.); (J.T.B.J.); (S.N.); (M.C.)
| | - Matthieu Chollet
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA; (C.A.); (V.S.A.); (M.R.); (G.C.); (R.R.); (D.S.); (L.G.); (T.S.); (P.L.K.); (S.L.R.); (B.H.); (P.S.); (A.T.G.-E.); (J.L.); (J.T.B.J.); (S.N.); (M.C.)
| | - Roberto Alonso-Mori
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA; (C.A.); (V.S.A.); (M.R.); (G.C.); (R.R.); (D.S.); (L.G.); (T.S.); (P.L.K.); (S.L.R.); (B.H.); (P.S.); (A.T.G.-E.); (J.L.); (J.T.B.J.); (S.N.); (M.C.)
| | - Tim B. van Driel
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA; (C.A.); (V.S.A.); (M.R.); (G.C.); (R.R.); (D.S.); (L.G.); (T.S.); (P.L.K.); (S.L.R.); (B.H.); (P.S.); (A.T.G.-E.); (J.L.); (J.T.B.J.); (S.N.); (M.C.)
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Chung T, McClain TP, Alonso-Mori R, Chollet M, Deb A, Garcia-Esparza AT, Huang Ze En J, Lamb RM, Michocki LB, Reinhard M, van Driel TB, Penner-Hahn JE, Sension RJ. Ultrafast X-ray Absorption Spectroscopy Reveals Excited-State Dynamics of B 12 Coenzymes Controlled by the Axial Base. J Phys Chem B 2024; 128:1428-1437. [PMID: 38301132 DOI: 10.1021/acs.jpcb.3c07779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2024]
Abstract
Polarized time-resolved X-ray absorption spectroscopy at the Co K-edge is used to probe the excited-state dynamics and photolysis of base-off methylcobalamin and the excited-state structure of base-off adenosylcobalamin. For both molecules, the final excited-state minimum shows evidence for an expansion of the cavity around the Co ion by ca. 0.04 to 0.05 Å. The 5-coordinate base-off cob(II)alamin that is formed following photodissociation has a structure similar to that of the 5-coordinate base-on cob(II)alamin, with a ring expansion of 0.03 to 0.04 Å and a contraction of the lower axial bond length relative to that in the 6-coordinate ground state. These data provide insights into the role of the lower axial ligand in modulating the reactivity of B12 coenzymes.
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Affiliation(s)
- Taewon Chung
- Department of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 481091055, United States
| | - Taylor P McClain
- Biophysics, 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
| | - Matthieu Chollet
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Aniruddha Deb
- Department of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 481091055, United States
| | - Angel T Garcia-Esparza
- Stanford Synchrotron Radiation Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025-7015, United States
| | - Joel Huang Ze En
- Department of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 481091055, United States
| | - Ryan M Lamb
- Department of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 481091055, United States
| | - Lindsay B Michocki
- Department of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 481091055, United States
| | - Marco Reinhard
- Stanford Synchrotron Radiation Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025-7015, United States
| | - 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 481091055, United States
- Biophysics, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 48109-1055, United States
| | - Roseanne J Sension
- Department of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 481091055, United States
- Department of Physics, University of Michigan, 450 Church Street, Ann Arbor, Michigan 48109-1040, United States
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Bogacz I, Makita H, Simon PS, Zhang M, Doyle MD, Chatterjee R, Fransson T, Weninger C, Fuller F, Gee L, Sato T, Seaberg M, Alonso-Mori R, Bergmann U, Yachandra VK, Kern J, Yano J. Room temperature X-ray absorption spectroscopy of metalloenzymes with drop-on-demand sample delivery at XFELs. PURE APPL CHEM 2023; 95:891-897. [PMID: 38013689 PMCID: PMC10505480 DOI: 10.1515/pac-2023-0213] [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] [Indexed: 11/29/2023]
Abstract
X-ray crystallography and X-ray spectroscopy using X-ray free electron lasers plays an important role in understanding the interplay of structural changes in the protein and the chemical changes at the metal active site of metalloenzymes through their catalytic cycles. As a part of such an effort, we report here our recent development of methods for X-ray absorption spectroscopy (XAS) at XFELs to study dilute biological samples, available in limited volumes. Our prime target is Photosystem II (PS II), a multi subunit membrane protein complex, that catalyzes the light-driven water oxidation reaction at the Mn4CaO5 cluster. This is an ideal system to investigate how to control multi-electron/proton chemistry, using the flexibility of metal redox states, in coordination with the protein and the water network. We describe the method that we have developed to collect XAS data using PS II samples with a Mn concentration of <1 mM, using a drop-on-demand sample delivery method.
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Affiliation(s)
- Isabel Bogacz
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, 94720, Berkeley, CA, USA
| | - Hiroki Makita
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, 94720, Berkeley, CA, USA
| | - Philipp S. Simon
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, 94720, Berkeley, CA, USA
| | - Miao Zhang
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, 94720, Berkeley, CA, USA
| | - Margaret D. Doyle
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, 94720, Berkeley, CA, USA
| | - Ruchira Chatterjee
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, 94720, Berkeley, CA, USA
| | - Thomas Fransson
- Department of Theoretical chemistry and Biology, KTH Royal Institute of Technology, Stockholm, Sweden
| | | | - Franklin Fuller
- LCLS, SLAC National Accelerator Laboratory, 94025, Menlo Park, CA, USA
| | - Leland Gee
- LCLS, SLAC National Accelerator Laboratory, 94025, Menlo Park, CA, USA
| | - Takahiro Sato
- LCLS, SLAC National Accelerator Laboratory, 94025, Menlo Park, CA, USA
| | - Matthew Seaberg
- LCLS, SLAC National Accelerator Laboratory, 94025, Menlo Park, CA, USA
| | | | - Uwe Bergmann
- Department of Physics, University of Wisconsin-Madison, 53706, Madison, WI, USA
| | - Vittal K. Yachandra
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, 94720, Berkeley, CA, USA
| | - Jan Kern
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, 94720, Berkeley, CA, USA
| | - Junko Yano
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, 94720, Berkeley, CA, USA
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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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6
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Sension RJ, Chung T, Dewan P, McClain TP, Lamb RM, Penner-Hahn JE. Time-resolved spectroscopy: Advances in understanding the electronic structure and dynamics of cobalamins. Methods Enzymol 2022; 669:303-331. [DOI: 10.1016/bs.mie.2022.01.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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7
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Shelby ML, Wildman A, Hayes D, Mara MW, Lestrange PJ, Cammarata M, Balducci L, Artamonov M, Lemke HT, Zhu D, Seideman T, Hoffman BM, Li X, Chen LX. Interplays of electron and nuclear motions along CO dissociation trajectory in myoglobin revealed by ultrafast X-rays and quantum dynamics calculations. Proc Natl Acad Sci U S A 2021; 118:e2018966118. [PMID: 33782122 PMCID: PMC8040624 DOI: 10.1073/pnas.2018966118] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Ultrafast structural dynamics with different spatial and temporal scales were investigated during photodissociation of carbon monoxide (CO) from iron(II)-heme in bovine myoglobin during the first 3 ps following laser excitation. We used simultaneous X-ray transient absorption (XTA) spectroscopy and X-ray transient solution scattering (XSS) at an X-ray free electron laser source with a time resolution of 80 fs. Kinetic traces at different characteristic X-ray energies were collected to give a global picture of the multistep pathway in the photodissociation of CO from heme. In order to extract the reaction coordinates along different directions of the CO departure, XTA data were collected with parallel and perpendicular relative polarizations of the laser pump and X-ray probe pulse to isolate the contributions of electronic spin state transition, bond breaking, and heme macrocycle nuclear relaxation. The time evolution of the iron K-edge X-ray absorption near edge structure (XANES) features along the two major photochemical reaction coordinates, i.e., the iron(II)-CO bond elongation and the heme macrocycle doming relaxation were modeled by time-dependent density functional theory calculations. Combined results from the experiments and computations reveal insight into interplays between the nuclear and electronic structural dynamics along the CO photodissociation trajectory. Time-resolved small-angle X-ray scattering data during the same process are also simultaneously collected, which show that the local CO dissociation causes a protein quake propagating on different spatial and temporal scales. These studies are important for understanding gas transport and protein deligation processes and shed light on the interplay of active site conformational changes and large-scale protein reorganization.
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Affiliation(s)
- Megan L Shelby
- Department of Chemistry, Northwestern University, Evanston, IL 60208
| | - Andrew Wildman
- Department of Chemistry, University of Washington, Seattle, WA 98195
| | - Dugan Hayes
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, IL 60437
| | - Michael W Mara
- Department of Chemistry, Northwestern University, Evanston, IL 60208
| | | | - Marco Cammarata
- Institut de Physique de Rennes, Université de Rennes, 35042 Rennes CEDEX, France
| | - Lodovico Balducci
- Institut de Physique de Rennes, Université de Rennes, 35042 Rennes CEDEX, France
| | - Maxim Artamonov
- Department of Chemistry, Northwestern University, Evanston, IL 60208
| | - Henrik T Lemke
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA 94025
| | - Diling Zhu
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA 94025
| | - Tamar Seideman
- Department of Chemistry, Northwestern University, Evanston, IL 60208
| | - Brian M Hoffman
- Department of Chemistry, Northwestern University, Evanston, IL 60208;
| | - Xiaosong Li
- Department of Chemistry, University of Washington, Seattle, WA 98195;
| | - Lin X Chen
- Department of Chemistry, Northwestern University, Evanston, IL 60208;
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, IL 60437
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8
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Toda MJ, Lodowski P, Thurman TM, Kozlowski PM. Light Mediated Properties of a Thiolato-Derivative of Vitamin B 12. Inorg Chem 2020; 59:17200-17212. [PMID: 33211475 DOI: 10.1021/acs.inorgchem.0c02414] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Vitamin B12 derivatives (Cbls = cobalamins) exhibit photolytic properties upon excitation with light. These properties can be modulated by several factors including the nature of the axial ligands. Upon excitation, homolytic cleavage of the organometallic bond to the upper axial ligand takes place in photolabile Cbls. The photosensitive nature of Cbls has made them potential candidates for light-activated drug delivery. The addition of a fluorophore to the nucleotide loop of thiolato Cbls has been shown to shift the region of photohomolysis to within the optical window of tissue (600-900 nm). With this possibility, there is a need to analyze photolytic properties of unique Cbls which contain a Co-S bond. Herein, the photodissociation of one such Cbl, namely, N-acetylcysteinylcobalamin (NACCbl), is analyzed based on density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations. The S0 and S1 potential energy surfaces (PESs), as a function of axial bond lengths, were computed to determine the mechanism of photodissociation. Like other Cbls, the S1 PES contains metal-to-ligand charge transfer (MLCT) and ligand field (LF) regions, but there are some unique differences. Interestingly, the S1 PES of NACCbl contains three distinct minima regions opening several possibilities for the mechanism of radical pair (RP) formation. The mild photoresponsiveness, observed experimentally, can be attributed to the small gap in energy between the S1 and S0 PESs. Compared to other Cbls, the gap shown for NACCbl is neither exactly in line with the alkyl Cbls nor the nonalkyl Cbls.
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Affiliation(s)
- Megan J Toda
- Department of Chemistry, University of Louisville, Louisville, Kentucky 40292, United States
| | - Piotr Lodowski
- Department of Theoretical Chemistry, Institute of Chemistry, University of Silesia in Katowice, Szkolna 9, PL-40 006 Katowice, Poland
| | - Todd M Thurman
- Department of Chemistry, University of Louisville, Louisville, Kentucky 40292, United States
| | - Pawel M Kozlowski
- Department of Chemistry, University of Louisville, Louisville, Kentucky 40292, United States
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9
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Miller NA, Kaneshiro AK, Konar A, Alonso-Mori R, Britz A, Deb A, Glownia JM, Koralek JD, Mallik L, Meadows JH, Michocki LB, van Driel TB, Koutmos M, Padmanabhan S, Elías-Arnanz M, Kubarych KJ, Marsh ENG, Penner-Hahn JE, Sension RJ. The Photoactive Excited State of the B 12-Based Photoreceptor CarH. J Phys Chem B 2020; 124:10732-10738. [PMID: 33174757 DOI: 10.1021/acs.jpcb.0c09428] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
We have used transient absorption spectroscopy in the UV-visible and X-ray regions to characterize the excited state of CarH, a protein photoreceptor that uses a form of B12, adenosylcobalamin (AdoCbl), to sense light. With visible excitation, a nanosecond-lifetime photoactive excited state is formed with unit quantum yield. The time-resolved X-ray absorption near edge structure difference spectrum of this state demonstrates that the excited state of AdoCbl in CarH undergoes only modest structural expansion around the central cobalt, a behavior similar to that observed for methylcobalamin rather than for AdoCbl free in solution. We propose a new mechanism for CarH photoreactivity involving formation of a triplet excited state. This allows the sensor to operate with high quantum efficiency and without formation of potentially dangerous side products. By stabilizing the excited electronic state, CarH controls reactivity of AdoCbl and enables slow reactions that yield nonreactive products and bypass bond homolysis and reactive radical species formation.
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Affiliation(s)
- Nicholas A Miller
- Department of Chemistry, University of Michigan, 930 N University Ave. Ann Arbor, Michigan 48109-1055, United States
| | - April K Kaneshiro
- Department of Biological Chemistry, University of Michigan, 1150 W. Medical Center Dr., Ann Arbor, Michigan 48109-0600, United States
| | - Arkaprabha Konar
- Department of Physics, University of Michigan, 450 Church Street, Ann Arbor, Michigan 48109-1040, United States
| | - Roberto Alonso-Mori
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Alexander Britz
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States.,Stanford PULSE Institute, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Aniruddha Deb
- Department of Chemistry, University of Michigan, 930 N University Ave. Ann Arbor, Michigan 48109-1055, United States.,Department of Biophysics, University of Michigan, 930 N University Ave. Ann Arbor, Michigan 48109-1055, United States
| | - James M Glownia
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Jake D Koralek
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Leena Mallik
- Department of Chemistry, University of Michigan, 930 N University Ave. Ann Arbor, Michigan 48109-1055, United States
| | - Joseph H Meadows
- Department of Chemistry, University of Michigan, 930 N University Ave. Ann Arbor, Michigan 48109-1055, United States
| | - Lindsay B Michocki
- Department of Chemistry, University of Michigan, 930 N University Ave. Ann Arbor, Michigan 48109-1055, United States
| | - Tim B van Driel
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Markos Koutmos
- Department of Chemistry, University of Michigan, 930 N University Ave. Ann Arbor, Michigan 48109-1055, United States.,Department of Biophysics, University of Michigan, 930 N University Ave. Ann Arbor, Michigan 48109-1055, United States
| | - S Padmanabhan
- Instituto de Química Física "Rocasolano", Consejo Superior de Investigaciones Científicas, Madrid 28006, Spain
| | - Montserrat Elías-Arnanz
- Departamento de Genética y Microbiología, Área de Genética (Unidad Asociada al Instituto de Química Física "Rocasolano", Consejo Superior de Investigaciones Científicas), Facultad de Biología, Universidad de Murcia, Murcia 30100, Spain
| | - Kevin J Kubarych
- Department of Chemistry, University of Michigan, 930 N University Ave. Ann Arbor, Michigan 48109-1055, United States
| | - E Neil G Marsh
- Department of Chemistry, University of Michigan, 930 N University Ave. Ann Arbor, Michigan 48109-1055, United States
| | - James E Penner-Hahn
- Department of Chemistry, University of Michigan, 930 N University Ave. Ann Arbor, Michigan 48109-1055, United States.,Department of Biophysics, University of Michigan, 930 N University Ave. Ann Arbor, Michigan 48109-1055, United States
| | - Roseanne J Sension
- Department of Chemistry, University of Michigan, 930 N University Ave. Ann Arbor, Michigan 48109-1055, United States.,Department of Physics, University of Michigan, 450 Church Street, Ann Arbor, Michigan 48109-1040, United States.,Department of Biophysics, University of Michigan, 930 N University Ave. Ann Arbor, Michigan 48109-1055, United States
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10
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Miller NA, Michocki LB, Konar A, Alonso-Mori R, Deb A, Glownia JM, Sofferman DL, Song S, Kozlowski PM, Kubarych KJ, Penner-Hahn JE, Sension RJ. Ultrafast XANES Monitors Femtosecond Sequential Structural Evolution in Photoexcited Coenzyme B 12. J Phys Chem B 2020; 124:199-209. [PMID: 31850761 DOI: 10.1021/acs.jpcb.9b09286] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Polarized X-ray absorption near-edge structure (XANES) at the Co K-edge and broadband UV-vis transient absorption are used to monitor the sequential evolution of the excited-state structure of coenzyme B12 (adenosylcobalamin) over the first picosecond following excitation. The initial state is characterized by sub-100 fs sequential changes around the central cobalt. These are polarized first in the y-direction orthogonal to the transition dipole and 50 fs later in the x-direction along the transition dipole. Expansion of the axial bonds follows on a ca. 200 fs time scale as the molecule moves out of the Franck-Condon active region of the potential energy surface. On the same 200 fs time scale there are electronic changes that result in the loss of stimulated emission and the appearance of a strong absorption at 340 nm. These measurements provide a cobalt-centered movie of the excited molecule as it evolves to the local excited-state minimum.
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Affiliation(s)
- Nicholas A Miller
- Department of Chemistry , University of Michigan , 930 N. University Ave. , Ann Arbor , Michigan 48109-1055 , United States
| | - Lindsay B Michocki
- Department of Chemistry , University of Michigan , 930 N. University Ave. , Ann Arbor , Michigan 48109-1055 , United States
| | - Arkaprabha Konar
- Department of Physics , University of Michigan , 450 Church Street , Ann Arbor , Michigan 48109-1040 , United States
| | - Roberto Alonso-Mori
- Linac Coherent Light Source , SLAC National Accelerator Laboratory , 2575 Sand Hill Road , Menlo Park , California 94025 , United States
| | - Aniruddha Deb
- Department of Chemistry , University of Michigan , 930 N. University Ave. , Ann Arbor , Michigan 48109-1055 , United States.,Department of Biophysics , University of Michigan , 930 N. University Ave. , Ann Arbor , Michigan 48109-1055 , United States
| | - James M Glownia
- Linac Coherent Light Source , SLAC National Accelerator Laboratory , 2575 Sand Hill Road , Menlo Park , California 94025 , United States
| | - Danielle L Sofferman
- Program in Applied Physics , University of Michigan , 450 Church Street , Ann Arbor , Michigan 48109-1040 , United States
| | - Sanghoon Song
- Linac Coherent Light Source , SLAC National Accelerator Laboratory , 2575 Sand Hill Road , Menlo Park , California 94025 , United States
| | - Pawel M Kozlowski
- Department of Chemistry , University of Louisville , 2320 South Brook Street , Louisville , Kentucky 40292 , United States
| | - Kevin J Kubarych
- Department of Chemistry , University of Michigan , 930 N. University Ave. , Ann Arbor , Michigan 48109-1055 , United States.,Department of Biophysics , University of Michigan , 930 N. University Ave. , Ann Arbor , Michigan 48109-1055 , United States
| | - James E Penner-Hahn
- Department of Chemistry , University of Michigan , 930 N. University Ave. , Ann Arbor , Michigan 48109-1055 , United States.,Department of Biophysics , University of Michigan , 930 N. University Ave. , Ann Arbor , Michigan 48109-1055 , United States
| | - Roseanne J Sension
- Department of Chemistry , University of Michigan , 930 N. University Ave. , Ann Arbor , Michigan 48109-1055 , United States.,Department of Physics , University of Michigan , 450 Church Street , Ann Arbor , Michigan 48109-1040 , United States.,Department of Biophysics , University of Michigan , 930 N. University Ave. , Ann Arbor , Michigan 48109-1055 , United States
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11
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Miller NA, Michocki LB, Alonso-Mori R, Britz A, Deb A, DePonte DP, Glownia JM, Kaneshiro AK, Kieninger C, Koralek J, Meadows JH, van Driel TB, Kräutler B, Kubarych KJ, Penner-Hahn JE, Sension RJ. Antivitamins B 12 in a Microdrop: The Excited-State Structure of a Precious Sample Using Transient Polarized X-ray Absorption Near-Edge Structure. J Phys Chem Lett 2019; 10:5484-5489. [PMID: 31483136 DOI: 10.1021/acs.jpclett.9b02202] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Polarized transient X-ray absorption near-edge structure (XANES) was used to probe the excited-state structure of a photostable B12 antivitamin (Coβ-2-(2,4-difluorophenyl)-ethynylcobalamin, F2PhEtyCbl). A drop-on-demand delivery system synchronized to the LCLS X-ray free electron laser pulses was implemented and used to measure the XANES difference spectrum 12 ps following excitation, exposing only ∼45 μL of sample. Unlike cyanocobalamin (CNCbl), where the Co-C bond expands 15-20%, the excited state of F2PhEtyCbl is characterized by little change in the Co-C bond, suggesting that the acetylide linkage raises the barrier for expansion of the Co-C bond. In contrast, the lower axial Co-NDMB bond is elongated in the excited state of F2PhEtyCbl by ca. 10% or more, comparable to the 10% elongation observed for Co-NDMB in CNCbl.
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Affiliation(s)
- Nicholas A Miller
- Department of Chemistry , University of Michigan , 930 North University Avenue , Ann Arbor , Michigan 48109-1055 , United States
| | - Lindsay B Michocki
- Department of Chemistry , University of Michigan , 930 North 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
| | - Alexander Britz
- Linac Coherent Light Source , SLAC National Accelerator Laboratory , 2575 Sand Hill Road , Menlo Park , California 94025 , United States
- Stanford PULSE Institute , SLAC National Accelerator Laboratory , 2575 Sand Hill Road , Menlo Park , California 94025 , United States
| | - Aniruddha Deb
- Department of Chemistry , University of Michigan , 930 North University Avenue , Ann Arbor , Michigan 48109-1055 , United States
- Biophysics , University of Michigan , 930 North University Avenue , Ann Arbor , Michigan 48109-1055 , United States
| | - Daniel P DePonte
- Linac Coherent Light Source , SLAC National Accelerator Laboratory , 2575 Sand Hill Road , Menlo Park , California 94025 , United States
| | - James M Glownia
- Linac Coherent Light Source , SLAC National Accelerator Laboratory , 2575 Sand Hill Road , Menlo Park , California 94025 , United States
| | - April K Kaneshiro
- Department of Biological Chemistry , 1150 West Medical Center Drive , Ann Arbor , Michigan 48109-0600 , United States
| | - Christoph Kieninger
- Institute of Organic Chemistry & Center for Molecular Biosciences , University of Innsbruck , Innrain 80/82 , A-6020 Innsbruck , Austria
| | - Jake Koralek
- Linac Coherent Light Source , SLAC National Accelerator Laboratory , 2575 Sand Hill Road , Menlo Park , California 94025 , United States
| | - Joseph H Meadows
- Department of Chemistry , University of Michigan , 930 North University Avenue , Ann Arbor , Michigan 48109-1055 , United States
| | - Tim B van Driel
- Linac Coherent Light Source , SLAC National Accelerator Laboratory , 2575 Sand Hill Road , Menlo Park , California 94025 , United States
| | - Bernhard Kräutler
- Institute of Organic Chemistry & Center for Molecular Biosciences , University of Innsbruck , Innrain 80/82 , A-6020 Innsbruck , Austria
| | - Kevin J Kubarych
- Department of Chemistry , University of Michigan , 930 North University Avenue , Ann Arbor , Michigan 48109-1055 , United States
- Biophysics , University of Michigan , 930 North University Avenue , Ann Arbor , Michigan 48109-1055 , United States
| | - James E Penner-Hahn
- Department of Chemistry , University of Michigan , 930 North University Avenue , Ann Arbor , Michigan 48109-1055 , United States
- Biophysics , University of Michigan , 930 North University Avenue , Ann Arbor , Michigan 48109-1055 , United States
| | - Roseanne J Sension
- Department of Chemistry , University of Michigan , 930 North University Avenue , Ann Arbor , Michigan 48109-1055 , United States
- Biophysics , University of Michigan , 930 North 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
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