Page "Methionine" Paragraph 26

* ( 5 ) Cystathionine-β-synthase ( a PLP-dependent enzyme ) combines homocysteine and serine to produce cystathionine.

Instead of degrading cystathionine via cystathionine-β-lyase, as in the biosynthetic pathway, cystathionine is broken down to cysteine and α-ketobutyrate via ( 6 ) cystathionine-γ-lyase.