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EC 4.4.1.11 Details
show Brenda entryEC number
4.4.1.11
Accepted name
methionine γ-lyase
Reaction
L-methionine + H2O = methanethiol + NH3 + 2-oxobutanoate (overall reaction);;(1a) L-methionine = methanethiol + 2-aminobut-2-enoate;;(1b) 2-aminobut-2-enoate = 2-iminobutanoate (spontaneous);;(1c) 2-iminobutanoate + H2O = 2-oxobutanoate + NH3 (spontaneous)
Other name(s)
L-methioninase,
methionine lyase,
methioninase,
methionine dethiomethylase,
L-methionine γ-lyase,
L-methionine methanethiol-lyase (deaminating)
Systematic name
L-methionine methanethiol-lyase (deaminating; 2-oxobutanoate-forming)
CAS registry number
42616-25-1
Comment
A pyridoxal-phosphate protein. The enzyme cleaves a carbon-sulfur bond, releasing methanethiol and an unstable enamine product that tautomerizes to an imine form, which undergoes a hydrolytic deamination to form 2-oxobutanoate 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 is involved in L-methionine catabolism.
History
created 1976
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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
