The enzyme S-carboxymethylcysteine synthase (EC 4.5.1.5) catalyzes the reaction
This enzyme belongs to the family of lyases, specifically the class of carbon-halide lyases. The systematic name of this enzyme class is 3-chloro-<small>L</small>-alanine chloride-lyase (adding thioglycolate; S-carboxymethyl-L-cysteine-forming). This enzyme is also called S-carboxymethyl-L-cysteine synthase. It employs one cofactor, pyridoxal phosphate.