Antioxidant and Cell-Signaling Functions of Hydrogen Sulfide in the Central Nervous System

Figure 1

Biosynthesis of hydrogen sulfide (H₂S) from the cystathionine β-synthase (CBS), cystathionine γ-lyase (CSE), cysteine aminotransferase (CAT), and 3-mercaptopyruvate sulfurtransferase (3MST). From the metabolism of methionine, homocysteine is converted to cystathionine and H₂S is produced from the L-cysteine and homocysteine by enzymes CBS and CSE. L-cysteine in converted to serine and H₂S with the enzyme CBS. Cystine is converted to pyruvate, ammonia (NH₃), and H₂S with enzymes CSE. 3MST works in two ways such as 3MST/CAT and 3MST/DAO (D-amino acid oxidase) pathways to produce H₂S from L-cysteine and D-cysteine. SAM: S-Adenosylmethionine synthase; SAH: S-Adenosyl homocysteine hydrolase; DAO: D-Amino acid oxidase.