H2S Biogenesis by Human Cystathionine γ-Lyase Leads to the Novel Sulfur Metabolites Lanthionine and Homolanthionine and Is Responsive to the Grade of Hyperhomocysteinemia

Although there is a growing recognition of the significance of hydrogen sulfide (H(2)S) as a biological signaling molecule involved in vascular and nervous system functions, its biogenesis and regulation are poorly understood. It is widely assumed that desulfhydration of cysteine is the major source of H(2)S in mammals and is catalyzed by the transsulfuration pathway enzymes, cystathionine beta-synthase and cystathionine gamma-lyase (CSE). In...