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EC 4.4.1.13 Details
show Brenda entryEC number
4.4.1.13
Accepted name
cysteine-S-conjugate β-lyase
Reaction
an L-cysteine-S-conjugate + H2O = a thiol + NH3 + pyruvate (overall reaction);;(1a) an L-cysteine-S-conjugate = a thiol + 2-aminoprop-2-enoate;;(1b) 2-aminoprop-2-enoate = 2-iminopropanoate (spontaneous);;(1c) 2-iminopropanoate + H2O = pyruvate + NH3 (spontaneous);;
Other name(s)
cysteine conjugate β-lyase,
glutamine transaminase K/cysteine conjugate β-lyase,
L-cysteine-S-conjugate thiol-lyase (deaminating),
cystathionine β-lyase,
β-cystathionase,
cystine lyase,
cystathionine L-homocysteine-lyase (deaminating),
L-cystathionine L-homocysteine-lyase (deaminating),
CBL,
S-alkylcysteine lyase,
S-alkylcysteinase,
alkylcysteine lyase,
S-alkyl-L-cysteine lyase,
S-alkyl-L-cysteinase,
alkyl cysteine lyase,
S-alkyl-L-cysteine alkylthiol-lyase (deaminating)
Systematic name
L-cysteine-S-conjugate thiol-lyase (deaminating; 2-aminoprop-2-enoate-forming)
CAS registry number
68652-57-3
Comment
A pyridoxal-phosphate protein. The enzyme is promiscuous regarding the moiety conjugated to L-cysteine, and can accept both aliphatic and aromatic substitutions. 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. While bacteria and plants have dedicated enzymes, all of the animal enzymes discovered thus far are bifunctional, most of which also act as aminotransferases.
History
created 1981, modified 2018 (EC 4.4.1.6 created 1965, deleted 1972, reinstated 1976, incorporated 2018) (EC 4.4.1.8 created 1972, incorporated 2018)
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1 Oxidoreductases
1.1 Acting on the CH-OH group of donors
4.4.1.7 created 1972, deleted 1976 4.4.1.12 created 1976, deleted 2003 4.4.1.18 created 2000, deleted 2002
