Methionine gamma-lyase

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methionine gamma-lyase
EC number
CAS number 42616-25-1
IntEnz IntEnz view
ExPASy NiceZyme view
MetaCyc metabolic pathway
PRIAM profile
PDB structures RCSB PDB PDBe PDBsum
Gene Ontology AmiGO / EGO

In enzymology, a methionine gamma-lyase (EC is an enzyme that catalyzes the chemical reaction

L-methionine + H2O \rightleftharpoons methanethiol + NH3 + 2-oxobutanoate

Thus, the two substrates of this enzyme are L-methionine and H2O, whereas its 3 products are methanethiol, NH3, and 2-oxobutanoate.

This enzyme belongs to the family of lyases, specifically the class of carbon-sulfur lyases. The systematic name of this enzyme class is L-methionine methanethiol-lyase (deaminating 2-oxobutanoate-forming). Other names in common use include L-methioninase, methionine lyase, methioninase, methionine dethiomethylase, L-methionine gamma-lyase, and L-methionine methanethiol-lyase (deaminating). This enzyme participates in selenoamino acid metabolism. It employs one cofactor, pyridoxal phosphate.

Structural studies[edit]

As of late 2007, 8 structures have been solved for this class of enzymes, with PDB accession codes 1E5E, 1E5F, 1GC0, 1GC2, 1PFF, 1PG8, 1UKJ, and 1Y4I.


  • Kreis W, Hession C (1973). "Isolation and purification of L-methionine-alpha-deamino-gamma-mercaptomethane-lyase (L-methioninase) from Clostridium sporogenes". Cancer. Res. 33 (8): 1862–5. PMID 4720797.