IUBMB Enzyme Nomenclature


Accepted name: cystathionine β-synthase

Reaction: L-serine + L-homocysteine = L-cystathionine + H2O

For diagram of reaction click here.

Other name(s): serine sulfhydrase; β-thionase; methylcysteine synthase; cysteine synthase (incorrect); serine sulfhydrylase; L-serine hydro-lyase (adding homocysteine)

Systematic name: L-serine hydro-lyase (adding homocysteine; L-cystathionine-forming)

Comments: 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: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number: 9023-99-8


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 (1971) 247-260. [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 (1968) 209-214. [PMID: 5672136]

3. Schlossmann, K., Brüggemann, J. and Lynen, F. Biosynthese des Cysteins. I. Nachweis und Isolierung der Serinsulfhydrase aus Bäckerhefe. Biochem. Z. 336 (1962) 258-273.

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

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