The enzyme cysteine lyase (EC 4.4.1.10) catalyzes the chemical reaction
-cysteine + sulfite formula_1 -cysteate + hydrogen sulfide
This enzyme belongs to the family of lyases, specifically the class of carbon-sulfur lyases. The systematic name of this enzyme class is -cysteine hydrogen-sulfide-lyase (adding sulfite; -cysteate-forming). Other names in common use include cysteine (sulfite) lyase, and -cysteine hydrogen-sulfide-lyase (adding sulfite). This enzyme participates in cysteine and taurine metabolism. It employs one cofactor, pyridoxal phosphate.
Evolution.
Genes encoding cysteine lyase (CL) originated around 300 million years ago by a tandem gene duplication and neofunctionalization of cystathionine β-lyase (CBS) shortly after the split of mammalian and reptilian lineages. CL genes are found only in "Sauropsida" where they are involved in a metabolic pathway for sulfur metabolism in the chicken egg.
References.
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