Bioorthogonal Photocatalytic Protein Labeling and Cross-Linking Enabled by Stabilized Ketyl Radicals
Jiawei Tan1, Kejia Hao1, Yi Yuan2,3
1State Key Laboratory of Chemical Biology, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032 China.
Journal of the American Chemical Society
|November 28, 2025
Summary
Visible-light photocatalysis enables precise protein labeling in cells by generating specific radicals, overcoming limitations of traditional UV methods for studying biological processes.
Area of Science:
- Biochemistry
- Organic Chemistry
- Chemical Biology
Background:
- Radical reactions hold promise for biological applications but suffer from low selectivity.
- Existing methods often involve UV excitation, leading to unwanted side reactions like cycloadditions and hydrogen atom abstraction.
Purpose of the Study:
- To develop a highly selective method for radical generation in biological systems.
- To enable precise, site-specific protein labeling and analysis of biomolecular interactions in live cells.
Main Methods:
- Visible-light photocatalysis to generate diaryl ketyl radicals from benzophenones.
- Utilizing genetically incorporated benzophenone-based unnatural amino acids (Bpa).
- Employing radical-radical coupling for bioorthogonal reactions, avoiding UV-induced side reactions.
Main Results:
- Achieved precise live-cell protein labeling with minimal cytotoxicity, even in primary neuronal cultures.
- Demonstrated site-specific protein modification with high spatial selectivity.
- Quantified protein dimerization interfaces (PyrI4) and resolved protein interactions (Bcl-XL/Bid) involved in apoptosis.
Conclusions:
- Visible-light photocatalysis offers a robust, bioorthogonal alternative to UV-based cross-linking.
- This method allows for spatiotemporally controlled interrogation of dynamic biomolecular processes.
- The platform enables advanced studies of protein interactions and complex biological mechanisms.
