Highly sensitive detection of cysteine over glutathione and homo-cysteine: New insight into the Michael addition of mercapto group to maleimide

A fluorescence “off-on” probe CMP for thiols was designed with coumarin as the fluorophore and maleimide as the receptor. The sensing mechanism of Michael addition followed by intramolecular nucleophilic substitute ensures highly sensitive detection of Cys over GSH and Hcy as well as bioimaging of Cys in living cells.85