CTH,also named as Gamma-cystathionase and CSE,belongs to the trans-sulfuration enzymes family. It catalyzes the last step in the transsulfuration pathway from methionine to cysteine. CTH has broad substrate specificity. It converts cystathionine to cysteine,ammonia and 2-oxobutanoate. And it converts two cysteine molecules to lanthionine and hydrogen sulfide. CTH can also accept homocysteine as substrate. It specificity depends on the levels of the endogenous substrates. It generates the endogenous signaling molecule hydrogen sulfide (H2S),and so contributes to the regulation of blood pressure. The CSE/H2S pathway is upregulated in the heart in a murine model of CVB3-induced myocarditis and that inhibition of endogenous H2S is beneficial to treatment early in the disease while administration of exogenous H2S is protective to infected myocardium during the later stage. Defects in CTH are the cause of cystathioninuria.