EC |
4.4.1.35 |
Accepted name: |
L-cystine β-lyase |
Reaction: |
L-cystine + H2O = L-thiocysteine + pyruvate + NH3 (overall reaction) (1a) L-cystine = L-thiocysteine + 2-aminoprop-2-enoate (1b) 2-aminoprop-2-enoate = 2-iminopropanoate (spontaneous) (1c) 2-iminopropanoate + H2O = pyruvate + NH3 (spontaneous) |
Glossary: |
L-thiocysteine = S-sulfanyl-L-cysteine |
Other name(s): |
CORI3 (gene name) |
Systematic name: |
L-cystine thiocysteine-lyase (deaminating; pyruvate-forming) |
Comments: |
A pyridoxal 5′-phosphate protein. The enzyme cleaves a carbon-sulfur bond, releasing L-thiocysteine 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 3.5.99.10, 2-iminobutanoate/2-iminopropanoate deaminase. The enzyme from Brassica oleracea var. italica (broccoli) does not act on cysteine or cystathionine. |
References: |
1. |
Ukai, K. and Sekiya, J. Purification and characterization of cystine lyase a from broccoli Inflorescence. Biosci. Biotechnol. Biochem. 61 (1997) 1890–1895. [PMID: 27396740] |
2. |
Jones, P.R., Manabe, T., Awazuhara, M. and Saito, K. A new member of plant CS-lyases. A cystine lyase from Arabidopsis thaliana. J. Biol. Chem. 278 (2003) 10291–10296. [PMID: 12525491] |
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[EC 4.4.1.35 created 2017] |
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