IUBMB Enzyme Nomenclature


Accepted name: acireductone synthase

Reaction: 5-(methylthio)-2,3-dioxopentyl phosphate + H2O = 1,2-dihydroxy-5-(methylthio)pent-1-en-3-one + phosphate (overall reaction)
(1a) 5-(methylthio)-2,3-dioxopentyl phosphate = 2-hydroxy-5-(methylthio)-3-oxopent-1-enyl phosphate (probably spontaneous)
(1b) 2-hydroxy-5-(methylthio)-3-oxopent-1-enyl phosphate + H2O = 1,2-dihydroxy-5-(methylthio)pent-1-en-3-one + phosphate

For diagram click here.

Glossary: acireductone = 1,2-dihydroxy-5-(methylthio)pent-1-en-3-one

Other name(s): E1; E-1 enolase-phosphatase

Systematic name: 5-(methylthio)-2,3-dioxopentyl-phosphate phosphohydrolase (isomerizing)

Comments: This bifunctional enzyme first enolizes the substrate to form the intermediate 2-hydroxy-5-(methylthio)-3-oxopent-1-enyl phosphate, which is then dephosphorylated to form the acireductone 1,2-dihydroxy-5-(methylthio)pent-1-en-3-one [2]. The acireductone represents a branch point in the methione-salvage pathway as it is used in the formation of formate, CO and 3-(methylthio)propanoate by EC [acireductone dioxygenase (Ni2+-requiring)] and of formate and 4-methylthio-2-oxobutanoate either by a spontaneous reaction under aerobic conditions or by EC {acireductone dioxygenase [iron(II)-requiring]} [1,2].

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number:


1. Myers, R.W., Wray, J.W., Fish, S. and Abeles, R.H. Purification and characterization of an enzyme involved in oxidative carbon-carbon bond cleavage reactions in the methionine salvage pathway of Klebsiella pneumoniae. J. Biol. Chem. 268 (1993) 24785-24791. [PMID: 8227039]

2. Wray, J.W. and Abeles, R.H. The methionine salvage pathway in Klebsiella pneumoniae and rat liver. Identification and characterization of two novel dioxygenases. J. Biol. Chem. 270 (1995) 3147-3153. [PMID: 7852397]

[EC created 2006]

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