FRET ratiometric probes reveal the chiral-sensitive cysteine-dependent H2S production and regulation in living cells

Abstract

Hydrogen sulfide (H 2 S) is an endogenously produced gaseous signalling molecule with multiple biological functions. In order to visualize and quantify the endogenous in situ production of H 2 S in living cells, here we developed two new sulphide ratiometric probes (SR400 and SR550) based on fluorescence resonance energy transfer (FRET) strategy for live capture of H 2 S. The FRET-based probes show excellent selectivity toward H 2 S in a high thiol background under physiological buffer. The probe can be used to in situ visualize cysteine-dependent H 2 S production in a chiral-sensitive manner in living cells. The ratiometric imaging studies indicated that D-Cys induces more H 2 S production than that of L-Cys in mitochondria of human embryonic kidney 293 cells (HEK293). The cysteine mimics propargylglycine (PPG) has also been found to inhibit the cysteine-dependent endogenous H 2 S production in a chiral-sensitive manner in living cells. D-PPG inhibited D-Cys-dependent H 2 S production more efficiently than L-PPG, while, L-PPG inhibited L-Cys-dependent H 2 S production more efficiently than D-PPG. Our bioimaging studies support Kimura's discovery of H 2 S production from D-cysteine in mammalian cells and further highlight the potential of D-cysteine and its derivatives as an alternative strategy for classical H 2 S-releasing drugs.