Fluorophore–antibody conjugates with high photobleaching resistance, high chemical stability, and Fc-specific attachment is a great advantage for immunofluorescence imaging. Here, an Fc-binding protein (Z-domain) carrying a photo-cross-linker (p-benzoylphenylalanine, Bpa) fused with enhanced green fluorescent protein (EGFP), namely photoactivatable ZBpa–EGFP recombinant, was directly generated using the aminoacyl-tRNA synthetase/suppressor tRNA technique without any further modification. By employing the photoactivatable ZBpa–EGFP, an optimal approach was successfully developed which enabled EGFP to site-selectively and covalently attach to native antibody (IgG) with approximately 90% conjugation efficiency. After characterizing the Fc-specific and covalent manner of the EGFP-photoconjugated antibody, its excellent photobleaching resistance for immunofluorescence imaging was demonstrated in a model study by monitoring the toll-like receptor 4 (TLR4) expression in HepG2 cells. The proposed approach here for the preparation of a novel fluorescent antibody is available and reliable, which would play an important role in fluorescence immunoassay, and is expected to be extended to the generation of other biomolecule-photoconjugated antibodies, such as other fluorescent proteins for multiplex immunofluorescence imaging or reporter enzymes for highly sensitive enzyme immunoassays.
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This work was supported by the National Natural Scientific Foundation of China (81971998) and the Natural Scientific Foundation of Shandong Province (ZR2018MC009).
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Yu, XT., Fu, XY., Gao, XY. et al. Fc-specific and covalent conjugation of a fluorescent protein to a native antibody through a photoconjugation strategy for fabrication of a novel photostable fluorescent antibody. Anal Bioanal Chem (2020). https://doi.org/10.1007/s00216-020-03051-3
- Photoactivatable Z
- Fc-specific covalent conjugates
- Immunoglobulin G
- Photobleaching resistance