A coumarin-based probe coumarin-alkene ketone-benzylaminoguanine(CAKBG)containing both α,β-unsaturated ketone and SNAP-tagTM substrate was synthesized.By testing the UV-Vis absorp-tion spectra and fluorescence emission spectra of the probe CAKBG,the results show that the probe CAK-BG has a longer absorption wavelength in polar solvents(such as glycerol,ethylene glycol,water,DM-SO),and the probe CAKBG is not sensitive to the pH change of the solutions.In addition,spectral exper-iments show that both Cys and Hcy can cause a blue shift in the maximum absorption wavelength of the probe CAKBG,and when the excitation wavelength is 405 nm,both Cys and Hcy can cause the fluores-cence emission peak of the probe CAKBG at 487 nm to be significantly enhanced.Cell imaging results show that the thiol fluorescent probe CAKBG containing SNAP-tagTM substrate can image Cys and Hcy in living cells.The above results indicate that SNAP-TagTM protein labeling technology is expected to be widely used in cell imaging of thiol fluorescent probes in the future.
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