Time-Gated Detection of Cystathionine γ-Lyase Activity and Inhibition with a Selective, Luminogenic Hydrogen Sulfide Sensor

Herein, we report the design, synthesis, and characterization of a lanthanide^IIIcomplex-based probe for the time-gated luminescence detection of hydrogen sulfide (H₂S) in aqueous media. The probe's unique sensing mechanism relies on the selective reduction of azide to amine by sulfide, followed by intramolecular cyclization to form a quinolinone. The quinolinone is a sensitizer that absorbs near-UV light and transfers excitation energy to coordinated Tb^IIIor Eu^IIIions to trigger a strong “turn-on” luminescence response with ms-scale lifetimes characteristic of lanthanide complexes. Using this probe, we developed a robust, high throughput screening (HTS) assay for detecting H₂S generated by cystathionine γ-lyase (CSE), one of the main producers of H₂S in mammalian cells. In a 240-compound screen to identify potential CSE inhibitors, the Eu^IIIanalogue of the sensor showed a low false-positive rate and high Z′-factor (>0.7).