EC - Cysteine synthase

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IntEnz Enzyme Nomenclature


Accepted name:
cysteine synthase
Other names:
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
OAS sulfhydrylase
3-O-acetyl-L-serine:hydrogen-sulfide 2-amino-2-carboxyethyltransferase
O3-acetyl-L-serine:hydrogen-sulfide 2-amino-2-carboxyethyltransferase
Systematic name:
O-acetyl-L-serine:hydrogen-sulfide 2-amino-2-carboxyethyltransferase




A pyridoxal-phosphate protein. Some alkyl thiols, cyanide, pyrazole and some other heterocyclic compounds can act as acceptors. Not identical with EC (β-pyrazolylalanine synthase), EC (L-mimosine synthase) and EC (uracilylalanine synthase).

Links to other databases

Enzymes and pathways: NC-IUBMB , BRENDA , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , UniPathway
Protein domains and families: PROSITE:PDOC00700
Structural data: CSA , EC2PDB
Gene Ontology: GO:0004124
CAS Registry Number: 37290-89-4
UniProtKB/Swiss-Prot: (77) [show] [UniProt]


  1. Becker, M.A., Kredich, N.M. and Tomkins, G.M.
    The purification and characterization of O-acetylserine sulfhydrylase-A from Salmonella typhimurium.
    J. Biol. Chem. 244 : 2418-2427 (1969). [PMID: 4891157]
  2. Hara, S., Payne, M.A., Schnackerz, K.D. and Cook, P.F.
    A rapid purification procedure and computer-assisted sulfide ion selective electrode assay for O-acetylserine sulfhydrylase from Salmonella typhimurium.
    Protein Expr. Purif. 1 : 70-76 (1990). [PMID: 2152186]
  3. Ikegami, F., Kaneko, M., Lambein, F., Kuo, Y.-H. and Murakoshi, I.
    Difference between uracilylalanine synthases and cysteine synthases in Pisum sativum.
    Phytochemistry 26 : 2699-2704 (1987).
  4. Murakoshi, I., Kaneko, M., Koide, C. and Ikegami, F.
    Enzymatic-synthesis of the neuroexcitatory amino-acid quisqualic by cysteine synthase.
    Phytochemistry 25 : 2759-2763 (1986).
  5. Tai, C.H., Burkhard, P., Gani, D., Jenn, T., Johnson, C. and Cook, P.F.
    Characterization of the allosteric anion-binding site of O-acetylserine sulfhydrylase.
    Biochemistry 40 : 7446-7452 (2001). [PMID: 11412097]
  6. Bettati, S., Benci, S., Campanini, B., Raboni, S., Chirico, G., Beretta, S., Schnackerz, K.D., Hazlett, T.L., Gratton, E. and Mozzarelli, A.
    Role of pyridoxal 5'-phosphate in the structural stabilization of O-acetylserine sulfhydrylase.
    J. Biol. Chem. 275 : 40244-40251 (2000). [PMID: 10995767]

[EC created 1972 as, modified 1976, modified 1990, transferred 2002 to EC]