Fig 1.

Molecular targets of H₂S in mammalian system. Top left: H₂S has the ability to directly scavenge reactive oxygen and nitrogen species (ROS/RNS). Top right: H₂S targets metal cofactor of cytochrome c oxidase and leads to inhibition of cellular respiration. Oxidation of H₂S by sulfide quinone oxidoreductase (SQR) couples catabolism of H₂S with mitochondrial electron transport chain (ETC) and thus modulates cellular metabolism. Bottom left: ion channels which are involved in systemic responses to H₂S in blood vessels, heart, and neurons. Bottom right: H₂S targets cysteine thiols by S-persulfidation of intracellular signaling proteins and transcription factors which likely accounts for the downstream effects on inflammation, antioxidant response, cellular proliferation, and survival.