UV photochemistry of the L-cystine disulfide bridge in aqueous solution investigated by femtosecond X-ray absorption spectroscopy
The photolysis of disulfide bonds is implicated in denaturation of proteins exposed to ultraviolet light. Despite this biological relevance in stabilizing the structure of many proteins, the mechanisms of disulfide photolysis are still contested after decades of research. Herein, we report new insight into the photochemistry of L-cystine in aqueous solution by femtosecond X-ray absorption spectroscopy at the sulfur K-edge. We observe homolytic bond cleavage upon ultraviolet irradiation and the formation of thiyl radicals as the single primary photoproduct. Ultrafast thiyl decay due to geminate recombination proceeds at a quantum yield of >80 % within 20 ps. These dynamics coincide with the emergence of a secondary product, attributed to the generation of perthiyl radicals. From these findings, we suggest a mechanism of perthiyl radical generation from a vibrationally excited parent molecule that asymmetrically fragments along a carbon-sulfur bond. Our results point toward a dynamic photostability of the disulfide bridge in condensed-phase.
Authors
- Intae Eom (ORCID: https://orcid.org/0000-0002-3390-4052)
- Da Hong
- Tae Kyu Kim (ORCID: https://orcid.org/0000-0002-9578-5722)
- Antonia Freibert (ORCID: https://orcid.org/0000-0002-6197-2597)
- Miguel Ochmann (ORCID: https://orcid.org/0000-0001-8239-1153)
- Daewoong Nam (ORCID: https://orcid.org/0000-0002-4544-4663)
- Madhusudana Gopannagari (ORCID: https://orcid.org/0000-0003-1114-1637)
- Jessica Harich (ORCID: https://orcid.org/0000-0003-4028-8873)
- Rory Ma (ORCID: https://orcid.org/0000-0003-2555-618X)
- Briony A. Yorke (ORCID: https://orcid.org/0000-0002-1868-8435)
- Nils Huse (ORCID: https://orcid.org/0000-0002-3281-7600)
- Minseok Kim (ORCID: https://orcid.org/0000-0002-2504-1314)
- Yujin Kim (ORCID: https://orcid.org/0000-0002-7186-221X)
- Jae Hyuk Lee (ORCID: https://orcid.org/0000-0002-8186-0226)
- Sangsoo Kim (ORCID: https://orcid.org/0000-0003-4005-5404)
Institutions
- Pohang University of Science and Technology (KR)
- University of Leeds (GB)
- Korea Advanced Institute of Science and Technology (KR)
- Universität Hamburg (DE)
- Center for Free-Electron Laser Science (DE)
- Pohang Accelerator Laboratory
Publication Details
- Journal
- Nature Communications
- Published
- 2024-10-13
- DOI
- https://doi.org/10.1038/s41467-024-52748-x
- Citations
- 8
- Primary Topic
- Photochemistry and Electron Transfer Studies
- Type
- article
- Field-Weighted Citation Impact
- 3.56
Funders
- National Research Foundation
- Deutsche Forschungsgemeinschaft
- Korea Institute of Science and Technology
- Korea Institute of Science and Technology Information
- National Research Foundation of Korea
- International Max Planck Research School for Advanced Methods in Process and Systems Engineering
- Ministry of Science and ICT, South Korea
- Korea Research Environment Open Network
- Samsung
- Great Southern Development Commission, Government of Western Australia
- National Cancer Institute