Reaction: L-threonine = 2-oxobutanoate + NH3
For diagram of reaction click here.
Other name(s): threonine deaminase; L-serine dehydratase; serine deaminase; L-threonine dehydratase; threonine dehydrase; L-threonine deaminase; threonine dehydratase; L-threonine hydro-lyase (deaminating); L-threonine ammonia-lyase
Systematic name: L-threonine ammonia-lyase (2-oxobutanoate-forming)
Comments: The enzyme from many sources is a pyridoxal-phosphate protein; that from Pseudomonas putida is not. The enzyme from a number of sources also acts on L-serine, cf. EC 18.104.22.168, L-serine ammonia-lyase. The reaction catalysed probably involves initial elimination of water (hence the enzyme's original classification as EC 22.214.171.124, threonine dehydratase), followed by isomerization and hydrolysis of the product with C-N bond breakage.
Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, UM-BBD, CAS registry number: 774231-81-1
1. Cohn, M.S. and Phillips, A.T. Purification and characterization of a B6-independent threonine dehydratase from Pseudomonas putida. Biochemistry 13 (1974) 1208-1214. [PMID: 4814721]
2. Nishimura, J.S. and Greenberg, D.M. Purification and properties of L-threonine dehydrase of sheep liver. J. Biol. Chem. 236 (1961) 2684-2691. [PMID: 14479973]
3. Phillips, A.T. and Wood, W.A. The mechanism of action of 5'-adenylic acid-activated threonine dehydrase. J. Biol. Chem. 240 (1965) 4703-4309. [PMID: 5321308]
4. Shizuta, Y., Nakazawa, A., Tokushige, M. and Hayaishi, O. Studies on the interaction between regulatory enzymes and effectors. 3. Crystallization and characterization of adenosine 5'-monophosphate-dependent threonine deaminase from Escherichia coli. J. Biol. Chem. 244 (1969) 1883-1889. [PMID: 4889010]