IUBMB Enzyme Nomenclature


Accepted name: cystathionine γ-synthase

Reaction: O4-succinyl-L-homoserine + L-cysteine = L-cystathionine + succinate

For diagram of reaction click here.

Other name(s):O-succinyl-L-homoserine succinate-lyase (adding cysteine); O-succinylhomoserine (thiol)-lyase; homoserine O-transsuccinylase (ambiguous); O-succinylhomoserine synthase; O-succinylhomoserine synthetase; cystathionine synthase; cystathionine synthetase; homoserine transsuccinylase (ambiguous); 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

Comments: 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: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number: 9030-70-0


1. Flavin, M. and Slaughter, C. Enzymatic synthesis of homocysteine or methionine directly from O-succinyl-homoserine. Biochim. Biophys. Acta 132 (1967) 400-405. [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 (1966) 4463-4471. [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 (1967) 12-23. [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 (1967) 5644-5649.

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 (1998) 6827-6838. [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 (1998) 639-648. [PMID: 9531508]

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

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