Transsulfuration pathway
（重定向自Transsulfuration）
![The reverse transsulfuration pathway depicting the conversion of homocysteine to cysteine in reactions 5 and 6. The required homocysteine is synthesized from methionine in reactions 1, 2, and 3.](/Images/godic/202502/17/Met_pathway1240.gif")
The transsulfuration pathway is a metabolic pathway involving the interconversion of cysteine and homocysteine, through the intermediate cystathionine. This is in contrast to the direct sulfurylation pathways for the synthesis of cysteine or homocysteine via the replacement of the acetyl/succinyl group with free sulfide (via the cysK or cysM -encoded cysteine synthase and the metZ or metY -encoded homocysteine synthase, respectively).