Cysteine synthase
Class of enzymes
From Wikipedia, the free encyclopedia
Cysteine synthase (EC 2.5.1.47) is an enzyme that catalyzes the chemical reaction
| Cysteine synthase | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Identifiers | |||||||||
| EC no. | 2.5.1.47 | ||||||||
| CAS no. | 37290-89-4 | ||||||||
| Databases | |||||||||
| BRENDA | enzyme data | ||||||||
| ExPASy | NiceZyme view | ||||||||
| KEGG | enzyme entry | ||||||||
| MetaCyc | metabolic pathway | ||||||||
| Rhea | reactions | ||||||||
| PDB structures | RCSB PDB PDBe PDBsum | ||||||||
| Gene Ontology | AmiGO / QuickGO | ||||||||
| |||||||||
The two substrates of this enzyme first characterised from Salmonella typhimurium are O-acetylserine and hydrogen sulfide (H2S). Its products are acetic acid and cysteine.[1][2]
The enzyme can transfer the 2-amino-2-carboxyethyl group to other nucleophiles. For example, it has been found to be involved in the final step of the biosynthesis of quisqualic acid in the vine Quisqualis indica.[3] However, it has different selectivity to the enzyme uracilylalanine synthase, which also converts O-acetylserine to amino acid derivatives.[4] It uses pyridoxal phosphate as a cofactor.[5] Chloride and sulfate ions can act as inhibitors of the enzyme by binding at an allosteric site.[6]
This enzyme is a transferase, specifically those transferring aryl or alkyl groups other than methyl groups. The systematic name of this enzyme class is O3-acetyl-L-serine:hydrogen-sulfide 2-amino-2-carboxyethyltransferase. Other names in common use include O-acetyl-L-serine sulfhydrylase, O-acetyl-L-serine sulfohydrolase, O-acetylserine (thiol)-lyase, O-acetylserine (thiol)-lyase A, O-acetylserine sulfhydrylase, O3-acetyl-L-serine acetate-lyase (adding hydrogen-sulfide), acetylserine sulfhydrylase, cysteine synthetase, S-sulfocysteine synthase, 3-O-acetyl-L-serine:hydrogen-sulfide, and 2-amino-2-carboxyethyltransferase.[7] This enzyme participates in 3 metabolic pathways: cysteine metabolism, selenoamino acid metabolism, and sulfur metabolism.
