EC - Cystathionine γ-synthase

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IntEnz Enzyme Nomenclature


Accepted name:
cystathionine γ-synthase
Other names:
O-succinyl-L-homoserine succinate-lyase (adding cysteine)
O-succinylhomoserine (thiol)-lyase
O-succinylhomoserine synthase
O-succinylhomoserine synthetase
cystathionine synthase
cystathionine synthetase
homoserine O-transsuccinylase
homoserine transsuccinylase
4-O-succinyl-L-homoserine:L-cysteine S-(3-amino-3-carboxypropyl)transferase
Systematic name:
O4-succinyl-L-homoserine:L-cysteine S-(3-amino-3-carboxypropyl)transferase




A pyridoxal-phosphate protein. Also reacts with hydrogen sulfide and methanethiol as replacing agents, producing homocysteine and methionine, respectively. In the absence of thiol, can also catalyse β,γ-elimination to form 2-oxobutanoate, succinate and ammonia.

Links to other databases

Enzymes and pathways: NC-IUBMB , BRENDA , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , UniPathway
Protein domains and families: PROSITE:PDOC00677
Structural data: CSA , EC2PDB
Gene Ontology: GO:0003962 , GO:0102028
CAS Registry Number: 9030-70-0
UniProtKB/Swiss-Prot: (17) [show] [UniProt]


  1. Flavin, M. and Slaughter, C.
    Enzymatic synthesis of homocysteine or methionine directly from O-succinyl-homoserine.
    Biochim. Biophys. Acta 132 : 400-405 (1967). [PMID: 5340123]
  2. Kaplan, M.M. and Flavin, M.
    Cystathionine γ-synthetase of Salmonella. Catalytic properties of a new enzyme in bacterial methionine biosynthesis.
    J. Biol. Chem. 241 : 4463-4471 (1966). [PMID: 5922970]
  3. Wiebers, J.L. and Garner, H.R.
    Homocysteine and cysteine synthetases of Neurospora crassa. Purification, properties, and feedback control of activity.
    J. Biol. Chem. 242 : 12-23 (1967). [PMID: 6016326]
  4. Wiebers, J.L. and Garner, H.R.
    Acyl derivatives of homoserine as substrates for homocysteine synthesis in Neurospora crassa, yeast, and Escherichia coli.
    J. Biol. Chem. 242 : 5644-5649 (1967). [PMID: 12325384]
  5. Clausen, T., Huber, R., Prade, L., Wahl, M.C. and Messerschmidt, A.
    Crystal structure of Escherichia coli cystathionine γ-synthase at 1.5 Å resolution.
    EMBO J. 17 : 6827-6838 (1998). [PMID: 9843488]
  6. Ravanel, S., Gakiere, B., Job, D. and Douce, R.
    Cystathionine γ-synthase from Arabidopsis thaliana: purification and biochemical characterization of the recombinant enzyme overexpressed in Escherichia coli.
    Biochem. J. 331 : 639-648 (1998). [PMID: 9531508]

[EC created 1972 as EC, transferred 2002 to EC]