KEGG   ENZYME: 4.4.1.6Help
Entry
EC 4.4.1.6                  Enzyme                                 

Name
S-alkylcysteine lyase;
S-alkylcysteinase;
alkylcysteine lyase;
S-alkyl-L-cysteine sulfoxide lyase;
S-alkyl-L-cysteine lyase;
S-alkyl-L-cysteinase;
alkyl cysteine lyase;
S-alkyl-L-cysteine alkylthiol-lyase (deaminating)
Class
Lyases;
Carbon-sulfur lyases;
Carbon-sulfur lyases (only sub-subclass identified to date)
BRITE hierarchy
Sysname
S-alkyl-L-cysteine alkyl-thiol-lyase (deaminating; pyruvate-forming)
Reaction(IUBMB)
an S-alkyl-L-cysteine + H2O = an alkyl thiol + NH3 + pyruvate (overall reaction) [RN:R02953];
(1a) an S-alkyl-L-cysteine = an alkyl thiol + 2-aminoprop-2-enoate;
(1b) 2-aminoprop-2-enoate = 2-iminopropanoate (spontaneous);
(1c) 2-iminopropanoate + H2O = pyruvate + NH3 (spontaneous)
Reaction(KEGG)
Substrate
S-alkyl-L-cysteine [CPD:C02749];
H2O [CPD:C00001];
2-aminoprop-2-enoate;
2-iminopropanoate
Product
alkyl thiol [CPD:C00812];
NH3 [CPD:C00014];
pyruvate [CPD:C00022];
2-aminoprop-2-enoate;
2-iminopropanoate (spontaneous)
Comment
A pyridoxal-phosphate protein. The enzyme cleaves a carbon-sulfur bond, releasing an alkyl 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 3.5.99.10, 2-iminobutanoate/2-iminopropanoate deaminase. Possibly identical, in yeast, with EC 4.4.1.8 cystathionine beta-lyase.
History
EC 4.4.1.6 created 1965, deleted 1972, reinstated 1976
Reference
1
  Authors
Nomura, J., Nishizuka, Y. and Hayaishi, O.
  Title
S-Alkylcysteinase: enzymatic cleavage of S-methyl-L-cysteine and its sulfoxide.
  Journal
J. Biol. Chem. 238 (1963) 1441-1446.
Other DBs
ExplorEnz - The Enzyme Database: 
IUBMB Enzyme Nomenclature: 
ExPASy - ENZYME nomenclature database: 
BRENDA, the Enzyme Database: 
CAS: 
62213-27-8

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