EC - Cystathionine β-synthase

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IntEnz Enzyme Nomenclature


Accepted name:
cystathionine β-synthase
Other names:
cysteine synthase [incorrect]
methylcysteine synthase
serine sulfhydrase
serine sulfhydrylase
L-serine hydro-lyase (adding homocysteine)
Systematic name:
L-serine hydro-lyase (adding homocysteine; L-cystathionine-forming)




A pyridoxal-phosphate protein. A multifunctional enzyme: catalyses β-replacement reactions between L-serine, L-cysteine, cysteine thioethers, or some other β-substituted α-L-amino acids, and a variety of mercaptans.

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:0004122
CAS Registry Number: 9023-99-8
UniProtKB/Swiss-Prot: (11) [show] [UniProt]


  1. Braunstein, A.E., Goryachinkova, E.V., Tolosa, E.A., Willhardt, I.H. and Yefremova, L.L.
    Specificity and some other properties of liver serine sulphhydrase: evidence for its identity with cystathionine-synthase.
    Biochim. Biophys. Acta, 242: 247-260 (1971). [PMID: 5121611]
  2. Nakagawa, H. and Kimura, H.
    Purification and properties of cystathionine synthetase synthetase from rat liver: separation of cystathionine synthetase from serine dehydratase.
    Biochem. Biophys. Res. Commun. 32: 209-214 (1968). [PMID: 5672136]
  3. Schlossmann, K., Brüggemann, J. and Lynen, F.
    Biosynthese des Cysteins. I. Nachweis und Isolierung der Serinsulfhydrase aus Bäckerhefe.
    Biochem. Z. 336: 258-273 (1962). [PMID: 13991884]

[EC created 1961 (EC created 1961, incorporated 1964, EC created 1961, incorporated 1972)]