Module 2: Figure H2S generation
Generation of hydrogen sulfide (H2S).
Hydrogen sulfide (H2S) is generated from cysteine using a variety of enzymatic pathways. 1. Cystathionine β-synthase (CBS) acts on L-cysteine to release H2S. 2. Cystathionine γ-lyase (CSE) liberates H2S from L-cysteine using vitamin B6 as a cofactor. 3. The two-step process begins with L-cysteine and α-ketoglutarate being converted into 3 mercaptopyruvate (3MP) using vitamin B6 as a cofactor. β-Mercaptopyruvate sulfurtransferase (3MST) then liberates H2S from 3MP. D-cysteine can also be used to generate H2S following its conversion into 3MP by D-amino acid oxidase (DAO). Some of the actions of H2S are mediated through an S-sulfhydration reaction that has been implicated in the regulation of multiple cellular processes.