UV photochemistry of the L-cystine disulfide bridge in aqueous solution investigated by femtosecond X-ray absorption spectroscopy
Year: 2024
Type: article
Abstract: 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.
Source: Nature Communications
Language: English
Subfield: Radiation
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $6,790
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
OpenAlex ID: W4403366619