Structural Evolution of Photoexcited Methylcobalamin toward a CarH-like Metastable State: Evidence from Time-Resolved X-ray Absorption and X-ray Emission
CarH is a protein photoreceptor that uses a form of B<sub>12</sub>, 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.
Authors
- Nicholas A. Miller (ORCID: https://orcid.org/0000-0002-9146-5414)
- Fernando Ardana‐Lamas (ORCID: https://orcid.org/0000-0001-9028-5051)
- Sanghoon Song (ORCID: https://orcid.org/0000-0003-3493-1850)
- Dmitry Khakhulin (ORCID: https://orcid.org/0000-0002-4453-1204)
- Florian Otte (ORCID: https://orcid.org/0000-0002-2431-4464)
- Tim B. van Driel (ORCID: https://orcid.org/0000-0003-4070-3168)
- April K. Kaneshiro
- Yifeng Jiang (ORCID: https://orcid.org/0000-0003-0685-0498)
- Aniruddha Deb (ORCID: https://orcid.org/0000-0002-0331-9709)
- Kevin J. Kubarych (ORCID: https://orcid.org/0000-0003-1152-4734)
- Roseanne J. Sension (ORCID: https://orcid.org/0000-0001-6758-0132)
- Lindsay B. Michocki
- Roberto Alonso‐Mori (ORCID: https://orcid.org/0000-0002-5357-0934)
- Danielle L. Sofferman (ORCID: https://orcid.org/0000-0001-7386-4019)
- Taylor P. McClain (ORCID: https://orcid.org/0009-0009-3077-0966)
- Mykola Biednov (ORCID: https://orcid.org/0000-0003-2219-155X)
- Frederico A. Lima (ORCID: https://orcid.org/0000-0001-8106-2892)
- James E. Penner‐Hahn (ORCID: https://orcid.org/0000-0003-0314-1274)
- Joseph H. Meadows
- Yohei Uemura (ORCID: https://orcid.org/0000-0003-3164-7168)
- Ryan M. Lamb (ORCID: https://orcid.org/0000-0001-6458-3653)
- Taewon Chung
Institutions
- University of Michigan (US)
- SLAC National Accelerator Laboratory (US)
- Linac Coherent Light Source (US)
- European X-Ray Free-Electron Laser (DE)
Publication Details
- Journal
- The Journal of Physical Chemistry B
- Published
- 2024-08-16
- DOI
- https://doi.org/10.1021/acs.jpcb.4c03729
- Citations
- 2
- Primary Topic
- Porphyrin Metabolism and Disorders
- Type
- article
- Field-Weighted Citation Impact
- 0.47
Funders
- National Science Foundation
- U.S. Department of Energy
- National Institutes of Health
- Office of Science
- National Institute of General Medical Sciences
- Division of Chemistry
- Basic Energy Sciences
- SLAC National Accelerator Laboratory