ExplorEnz: EC 1.2.7.7

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1.2.7.7

Accepted name:

3-methyl-2-oxobutanoate dehydrogenase (ferredoxin)

Reaction:

3-methyl-2-oxobutanoate + CoA + 2 oxidized ferredoxin = S-(2-methylpropanoyl)-CoA + CO₂ + 2 reduced ferredoxin + H⁺

Other name(s):

2-ketoisovalerate ferredoxin reductase; 3-methyl-2-oxobutanoate synthase (ferredoxin); VOR; branched-chain ketoacid ferredoxin reductase; branched-chain oxo acid ferredoxin reductase; keto-valine-ferredoxin oxidoreductase; ketoisovalerate ferredoxin reductase; 2-oxoisovalerate ferredoxin reductase

Systematic name:

3-methyl-2-oxobutanoate:ferredoxin oxidoreductase (decarboxylating; CoA-2-methylpropanoylating)

Comments:

The enzyme is CoA-dependent and contains thiamine diphosphate and iron-sulfur clusters. Preferentially utilizes 2-oxo-acid derivatives of branched chain amino acids, e.g. 3-methyl-2-oxopentanoate, 4-methyl-2-oxo-pentanoate, and 2-oxobutanoate. This enzyme is a member of the 2-oxoacid oxidoreductases, a family of enzymes that reversibly catalyse the oxidative decarboxylation of different 2-oxoacids to form their CoA derivatives, and are differentiated based on their substrate specificity. For examples of other members of this family, see EC 1.2.7.1, pyruvate synthase, and EC 1.2.7.3, 2-oxoglutarate synthase.

Links to other databases:

BRENDA, EXPASY, Gene, KEGG, MetaCyc

References:

1.	Buchanan, B.B. Role of ferredoxin in the synthesis of α-ketobutyrate from propionyl coenzyme A and carbon dioxide by enzymes from photosynthetic and nonphotosynthetic bacteria. J. Biol. Chem. 244 (1969) 4218–4223. [PMID: 5800441]
2.	Heider, J., Mai, X.H. and Adams, M.W.W. Characterization of 2-ketoisovalerate ferredoxin oxidoreductase, a new and reversible coenzyme A-dependent enzyme involved in peptide fermentation by hyperthermophilic archaea. J. Bacteriol. 178 (1996) 780–787. [DOI] [PMID: 8550513]
3.	Tersteegen, A., Linder, D., Thauer, R.K. and Hedderich, R. Structures and functions of four anabolic 2-oxoacid oxidoreductases in Methanobacterium thermoautotrophicum. Eur. J. Biochem. 244 (1997) 862–868. [DOI] [PMID: 9108258]
4.	Schut, G.J., Menon, A.L. and Adams, M.W.W. 2-Keto acid oxidoreductases from Pyrococcus furiosus and Thermococcus litoralis. Methods Enzymol. 331 (2001) 144–158. [DOI] [PMID: 11265457]

[EC 1.2.7.7 created 2003]