Real Thiol, a reversible reaction-based fluorescent probe, can quantitatively monitor the real-time glutathione dynamics in living cells.

Real Thiol (RT) exhibits ratiometric fluorescence responses over a wide dynamic range when reacting with Glutathione (GSH). RT and its GSH adduct (RT-GSH) show fluorescence maxima at 487 nm and 562 nm with excitation wavelengths at 405 nm and 488 nm, respectively. The dissociation constant (Kd) for the RT-GSH reaction is 3.7 mM. RT's dynamic range (1 to 10 mM) enables monitoring of GSH level changes in both directions in living cells, with 10% of RT reacting with thiolated proteins and 90% with GSH [1].