FIGURE 3.
The hydrogen sulfide pathway (H2S) including involved substrates and enzymes. H2S is produced through enzymatic pathways of CSE, CBS and 3-MST. In addition, intestinal bacteria can also secrete H2S, and several exogenous substrates exist. Vitamin B6 and iron are also required for the non-enzymatic synthesis of H2S in blood. H2S exerts antioxidant effects through several mechanisms, such as increasing expression of AOE, by activating the transcription factor NRF2. CSE, Cystathionine gamma-lyase; CBS, Cystathionine beta-synthase; 3-MST, 3-mercatopyruvate; VitB, Vitamin B6; AOE, Antioxidant enzymes; NRF2, Nuclear factor erythroid-derived 2-like 2