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EC 4.4.1.25 Details
EC number
4.4.1.25
Accepted name
L-cysteate sulfo-lyase
Reaction
L-cysteate + H2O = hydrogensulfite + pyruvate + NH3 (overall reaction);;(1a) L-cysteate = hydrogensulfite + 2-aminoprop-2-enoate;;(1b) 2-aminoprop-2-enoate = 2-iminopropanoate (spontaneous);;(1c) 2-iminopropanoate + H2O = pyruvate + NH3 (spontaneous)
Other name(s)
L-cysteate sulfo-lyase (deaminating), CuyA, L-cysteate bisulfite-lyase (deaminating, pyruvate-forming)
Systematic name
L-cysteate hydrogensulfite-lyase (deaminating; pyruvate-forming)
Comment
A pyridoxal-phosphate protein. The enzyme cleaves a carbon-sulfur bond, releasing hydrogensulfite 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. D-Cysteine can also act as a substrate, but more slowly. It is converted into hydrogen sulfide, pyruvate, and ammonia. This inducible enzyme from the marine bacterium Silicibacter pomeroyi DSS-3 forms part of the cysteate-degradation pathway.
History
created 2006
EC Tree
3.1.1.9 created 1961, deleted 1972
3.1.1.12 created 1961, deleted 1972
3.1.1.16 created 1961, deleted 1972
3.1.1.18 created 1961, deleted 1982
3.1.1.62 created 1989, deleted 1992
3.1.1.69 created 1992, deleted 2002