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 complex-based probe for the time-gated luminescence detection of hydrogen sulfide (H S) 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 or Eu ions 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 H S generated by cystathionine γ-lyase (CSE), one of the main producers of H S in mammalian cells. In a 240-compound screen to identify potential CSE inhibitors, the Eu analogue of the sensor showed a low false-positive rate and high Z'-factor (>0.7).