EC - Cysteine-S-conjugate β-lyase

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IntEnz Enzyme Nomenclature


Accepted name:
cysteine-S-conjugate β-lyase
Other names:
cysteine conjugate β-lyase
glutamine transaminase K/cysteine conjugate β-lyase
L-cysteine-S-conjugate thiol-lyase (deaminating)
Systematic name:
L-cysteine-S-conjugate thiol-lyase (deaminating; pyruvate-forming)




A pyridoxal-phosphate protein. The enzyme can act on a broad range of L-cysteine-S-conjugates, including aromatic conjugates such as 4-bromobenzene and 2,4-dinitrobenzene. The enzyme cleaves a carbon-sulfur bond, releasing a thiol and an unstable enamine product that tautomerizes to an imine form, which undergoes a hydrolytic deamination to form pyruvate and ammonia. The latter reaction, which can occur spontaneously, can also be catalysed by EC, 2-iminobutanoate/2-iminopropanoate deaminase.

Links to other databases

Enzymes and pathways: NC-IUBMB , BRENDA , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , UniPathway
Structural data: CSA , EC2PDB
Gene Ontology: GO:0047804
CAS Registry Number: 68652-57-3


  1. Tateishi, M., Suzuki, S. and Shimizu, H.
    Cysteine conjugate β-lyase in rat liver. A novel enzyme catalyzing formation of thiol-containing metabolites of drugs.
    J. Biol. Chem. 253: 8854-8859 (1978). [PMID: 721818]

[EC created 1981]