The Enzyme Database

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EC 1.1.1.84     
Accepted name: dimethylmalate dehydrogenase
Reaction: (R)-3,3-dimethylmalate + NAD+ = 3-methyl-2-oxobutanoate + CO2 + NADH
For diagram of pantothenate catabolism, click here
Other name(s): β,β-dimethylmalate dehydrogenase
Systematic name: (R)-3,3-dimethylmalate:NAD+ oxidoreductase (decarboxylating)
Comments: Requires K+ or NH4+ and Mn2+ or Co2+; also acts on (R)-malate.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 37250-21-8
References:
1.  Magee, P.T. and Snell, E.E. The bacterial degradation of pantothenic acid. IV. Enzymatic conversion of aldopantoate to α-ketoisovalerate. Biochemistry 5 (1966) 409–416. [PMID: 4287371]
[EC 1.1.1.84 created 1972]
 
 
EC 1.2.1.25     
Accepted name: branched-chain α-keto acid dehydrogenase system
Reaction: 3-methyl-2-oxobutanoate + CoA + NAD+ = 2-methylpropanoyl-CoA + CO2 + NADH
Other name(s): branched-chain α-keto acid dehydrogenase complex; 2-oxoisovalerate dehydrogenase; α-ketoisovalerate dehydrogenase; 2-oxoisovalerate dehydrogenase (acylating)
Systematic name: 3-methyl-2-oxobutanoate:NAD+ 2-oxidoreductase (CoA-methylpropanoylating)
Comments: This enzyme system catalyses the oxidative decarboxylation of branched-chain α-keto acids derived from L-leucine, L-isoleucine, and L-valine to branched-chain acyl-CoAs. It belongs to the 2-oxoacid dehydrogenase system family, which also includes EC 1.2.1.104, pyruvate dehydrogenase system, EC 1.2.1.105, 2-oxoglutarate dehydrogenase system, EC 1.4.1.27, glycine cleavage system, and EC 2.3.1.190, acetoin dehydrogenase system. With the exception of the glycine cleavage system, which contains 4 components, the 2-oxoacid dehydrogenase systems share a common structure, consisting of three main components, namely a 2-oxoacid dehydrogenase (E1), a dihydrolipoamide acyltransferase (E2), and dihydrolipoamide dehydrogenase (E3). The reaction catalysed by this system is the sum of three activities: EC 1.2.4.4, 3-methyl-2-oxobutanoate dehydrogenase (2-methylpropanoyl-transferring), EC 2.3.1.168, dihydrolipoyllysine-residue (2-methylpropanoyl)transferase, and EC 1.8.1.4, dihydrolipoyl dehydrogenase. The system also acts on (S)-3-methyl-2-oxopentanoate and 4-methyl-2-oxopentanoate.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 37211-61-3
References:
1.  Namba, Y., Yoshizawa, K., Ejima, A., Hayashi, T. and Kaneda, T. Coenzyme A- and nicotinamide adenine dinucleotide-dependent branched chain α-keto acid dehydrogenase. I. Purification and properties of the enzyme from Bacillus subtilis. J. Biol. Chem. 244 (1969) 4437–4447. [PMID: 4308861]
2.  Pettit, F.H., Yeaman, S.J. and Reed, L.J. Purification and characterization of branched chain α-keto acid dehydrogenase complex of bovine kidney. Proc. Natl. Acad. Sci. USA 75 (1978) 4881–4885. [DOI] [PMID: 283398]
3.  Harris, R.A., Hawes, J.W., Popov, K.M., Zhao, Y., Shimomura, Y., Sato, J., Jaskiewicz, J. and Hurley, T.D. Studies on the regulation of the mitochondrial α-ketoacid dehydrogenase complexes and their kinases. Adv. Enzyme Regul. 37 (1997) 271–293. [DOI] [PMID: 9381974]
4.  Evarsson, A., Chuang, J.L., Wynn, R.M., Turley, S., Chuang, D.T. and Hol, W.G. Crystal structure of human branched-chain α-ketoacid dehydrogenase and the molecular basis of multienzyme complex deficiency in maple syrup urine disease. Structure 8 (2000) 277–291. [PMID: 10745006]
5.  Reed, L.J. A trail of research from lipoic acid to α-keto acid dehydrogenase complexes. J. Biol. Chem. 276 (2001) 38329–38336. [DOI] [PMID: 11477096]
[EC 1.2.1.25 created 1972, modified 2019, modified 2020]
 
 
EC 1.2.4.3      
Deleted entry:  2-oxoisocaproate dehydrogenase. Now included with EC 1.2.4.4, 3-methyl-2-oxobutanoate dehydrogenase (2-methylpropanoyl-transferring)
[EC 1.2.4.3 created 1972, deleted 1978]
 
 
EC 1.2.4.4     
Accepted name: 3-methyl-2-oxobutanoate dehydrogenase (2-methylpropanoyl-transferring)
Reaction: 3-methyl-2-oxobutanoate + [dihydrolipoyllysine-residue (2-methylpropanoyl)transferase] lipoyllysine = [dihydrolipoyllysine-residue (2-methylpropanoyl)transferase] S-(2-methylpropanoyl)dihydrolipoyllysine + CO2
For diagram of oxo-acid-dehydrogenase complexes, click here
Glossary: dihydrolipoyl group
thiamine diphosphate = 3-[(4-amino-2-methylpyrimidin-5-yl)methyl]-5-(2-diphosphoethyl)-4-methyl-1,3-thiazolium
Other name(s): 2-oxoisocaproate dehydrogenase; 2-oxoisovalerate (lipoate) dehydrogenase; 3-methyl-2-oxobutanoate dehydrogenase (lipoamide); 3-methyl-2-oxobutanoate:lipoamide oxidoreductase (decarboxylating and acceptor-2-methylpropanoylating); α-keto-α-methylvalerate dehydrogenase; α-ketoisocaproate dehydrogenase; α-ketoisocaproic dehydrogenase; α-ketoisocaproic-α-keto-α-methylvaleric dehydrogenase; α-ketoisovalerate dehydrogenase; α-oxoisocaproate dehydrogenase; BCKDH (ambiguous); BCOAD; branched chain keto acid dehydrogenase; branched-chain (-2-oxoacid) dehydrogenase (BCD); branched-chain 2-keto acid dehydrogenase; branched-chain 2-oxo acid dehydrogenase; branched-chain α-keto acid dehydrogenase; branched-chain α-oxo acid dehydrogenase; branched-chain keto acid dehydrogenase; branched-chain ketoacid dehydrogenase; dehydrogenase, 2-oxoisovalerate (lipoate); dehydrogenase, branched chain α-keto acid
Systematic name: 3-methyl-2-oxobutanoate:[dihydrolipoyllysine-residue (2-methylpropanoyl)transferase]-lipoyllysine 2-oxidoreductase (decarboxylating, acceptor-2-methylpropanoylating)
Comments: Contains thiamine diphosphate. It acts not only on 3-methyl-2-oxobutanaoate, but also on 4-methyl-2-oxopentanoate and (S)-3-methyl-2-oxopentanoate, so that it acts on the 2-oxo acids that derive from the action of transaminases on valine, leucine and isoleucine. It is a component of the multienzyme 3-methyl-2-oxobutanoate dehydrogenase complex in which multiple copies of it are bound to a core of molecules of EC 2.3.1.168, dihydrolipoyllysine-residue (2-methylpropanoyl)transferase, which also binds multiple copies of EC 1.8.1.4, dihydrolipoyl dehydrogenase. It does not act on free lipoamide or lipoyllysine, but only on the lipoyllysine residue in EC 2.3.1.168.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 9082-72-8
References:
1.  Bowden, J.A. and Connelly, J.L. Branched chain α-keto acid metabolism. II. Evidence for the common identity of α-ketoisocaproic acid and α-keto-β-methyl-valeric acid dehydrogenases. J. Biol. Chem. 243 (1968) 3526–3531. [PMID: 5656388]
2.  Connelly, J.L., Danner, D.J. and Bowden, J.A. Branched chain α-keto acid metabolism. I. Isolation, purification, and partial characterization of bovine liver α-ketoisocaproic:α-keto-β-methylvaleric acid dehydrogenase. J. Biol. Chem. 243 (1968) 1198–1203. [PMID: 5689906]
3.  Danner, D.J., Lemmon, S.K., Beharse, J.C. and Elsas, L.J., II Purification and characterization of branched chain α-ketoacid dehydrogenase from bovine liver mitochondria. J. Biol. Chem. 254 (1979) 5522–5526. [PMID: 447664]
4.  Pettit, F.H., Yeaman, S.J. and Reed, L.J. Purification and characterization of branched chain α-keto acid dehydrogenase complex of bovine kidney. Proc. Natl. Acad. Sci. USA 75 (1978) 4881–4885. [DOI] [PMID: 283398]
5.  Perham, R.N. Swinging arms and swinging domains in multifunctional enzymes: catalytic machines for multistep reactions. Annu. Rev. Biochem. 69 (2000) 961–1004. [DOI] [PMID: 10966480]
[EC 1.2.4.4 created 1972 (EC 1.2.4.3 created 1972, incorporated 1978), modified 2003]
 
 
EC 1.2.7.1     
Accepted name: pyruvate synthase
Reaction: pyruvate + CoA + 2 oxidized ferredoxin = acetyl-CoA + CO2 + 2 reduced ferredoxin + 2 H+
For diagram of the 3-hydroxypropanoate/4-hydroxybutanoate cycle and dicarboxylate/4-hydroxybutanoate cycle in archaea, click here
Other name(s): pyruvate oxidoreductase; pyruvate synthetase; pyruvate:ferredoxin oxidoreductase; pyruvic-ferredoxin oxidoreductase; 2-oxobutyrate synthase; α-ketobutyrate-ferredoxin oxidoreductase; 2-ketobutyrate synthase; α-ketobutyrate synthase; 2-oxobutyrate-ferredoxin oxidoreductase; 2-oxobutanoate:ferredoxin 2-oxidoreductase (CoA-propionylating); 2-oxobutanoate:ferredoxin 2-oxidoreductase (CoA-propanoylating)
Systematic name: pyruvate:ferredoxin 2-oxidoreductase (CoA-acetylating)
Comments: Contains thiamine diphosphate and [4Fe-4S] clusters. The enzyme also decarboxylates 2-oxobutyrate with lower efficiency, but shows no activity with 2-oxoglutarate. This enzyme is a member of the 2-oxoacid oxidoreductases, a family of enzymes that oxidatively decarboxylate 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 1.2.7.3, 2-oxoglutarate synthase and EC 1.2.7.7, 3-methyl-2-oxobutanoate dehydrogenase (ferredoxin).
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 9082-51-3
References:
1.  Evans, M.C.W. and Buchanan, B.B. Photoreduction of ferredoxin and its use in carbon dioxide fixation by a subcellular system from a photosynthetic bacterium. Proc. Natl. Acad. Sci. USA 53 (1965) 1420–1425. [DOI] [PMID: 5217644]
2.  Gehring, U. and Arnon, D.I. Purification and properties of α-ketoglutarate synthase from a photosynthetic bacterium. J. Biol. Chem. 247 (1972) 6963–6969. [PMID: 4628267]
3.  Uyeda, K. and Rabinowitz, J.C. Pyruvate-ferredoxin oxidoreductase. 3. Purification and properties of the enzyme. J. Biol. Chem. 246 (1971) 3111–3119. [PMID: 5574389]
4.  Uyeda, K. and Rabinowitz, J.C. Pyruvate-ferredoxin oxidoreductase. IV. Studies on the reaction mechanism. J. Biol. Chem. 246 (1971) 3120–3125. [PMID: 4324891]
5.  Charon, M.-H., Volbeda, A., Chabriere, E., Pieulle, L. and Fontecilla-Camps, J.C. Structure and electron transfer mechanism of pyruvate:ferredoxin oxidoreductase. Curr. Opin. Struct. Biol. 9 (1999) 663–669. [DOI] [PMID: 10607667]
[EC 1.2.7.1 created 1972, modified 2003, modified 2013]
 
 
EC 1.2.7.3     
Accepted name: 2-oxoglutarate synthase
Reaction: 2-oxoglutarate + CoA + 2 oxidized ferredoxin = succinyl-CoA + CO2 + 2 reduced ferredoxin + 2 H+
Other name(s): 2-ketoglutarate ferredoxin oxidoreductase; 2-oxoglutarate:ferredoxin oxidoreductase; KGOR; 2-oxoglutarate ferredoxin oxidoreductase; 2-oxoglutarate:ferredoxin 2-oxidoreductase (CoA-succinylating)
Systematic name: 2-oxoglutarate:ferredoxin oxidoreductase (decarboxylating)
Comments: The enzyme contains thiamine diphosphate and two [4Fe-4S] clusters. Highly specific for 2-oxoglutarate. This enzyme is a member of the 2-oxoacid oxidoreductases, a family of enzymes that oxidatively decarboxylate 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 1.2.7.7, 3-methyl-2-oxobutanoate dehydrogenase (ferredoxin).
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 37251-05-1
References:
1.  Buchanan, B.B. and Evans, M.C.W. The synthesis of α-ketoglutarate from succinate and carbon dioxide by a subcellular preparation of a photosynthetic bacterium. Proc. Natl. Acad. Sci. USA 54 (1965) 1212–1218. [DOI] [PMID: 4286833]
2.  Gehring, U. and Arnon, D.I. Purification and properties of α-ketoglutarate synthase from a photosynthetic bacterium. J. Biol. Chem. 247 (1972) 6963–6969. [PMID: 4628267]
3.  Dorner, E. and Boll, M. Properties of 2-oxoglutarate:ferredoxin oxidoreductase from Thauera aromatica and its role in enzymatic reduction of the aromatic ring. J. Bacteriol. 184 (2002) 3975–3983. [DOI] [PMID: 12081970]
4.  Mai, X. and Adams, M.W. Characterization of a fourth type of 2-keto acid-oxidizing enzyme from a hyperthermophilic archaeon: 2-ketoglutarate ferredoxin oxidoreductase from Thermococcus litoralis. J. Bacteriol. 178 (1996) 5890–5896. [DOI] [PMID: 8830683]
5.  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 1.2.7.3 created 1972, modified 2005]
 
 
EC 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, 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]
 
 
EC 1.2.7.8     
Accepted name: indolepyruvate ferredoxin oxidoreductase
Reaction: (indol-3-yl)pyruvate + CoA + 2 oxidized ferredoxin = S-2-(indol-3-yl)acetyl-CoA + CO2 + 2 reduced ferredoxin + H+
Other name(s): 3-(indol-3-yl)pyruvate synthase (ferredoxin); IOR
Systematic name: 3-(indol-3-yl)pyruvate:ferredoxin oxidoreductase (decarboxylating, CoA-indole-acetylating)
Comments: Contains thiamine diphosphate and [4Fe-4S] clusters. Preferentially utilizes the transaminated forms of aromatic amino acids and can use phenylpyruvate and p-hydroxyphenylpyruvate as substrates. This enzyme, which is found in archaea, is a member of the 2-oxoacid oxidoreductases, a family of enzymes that oxidatively decarboxylate 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 1.2.7.3, 2-oxoglutarate synthase and EC 1.2.7.7, 3-methyl-2-oxobutanoate dehydrogenase (ferredoxin).
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 158886-06-7
References:
1.  Mai, X.H. and Adams, M.W.W. Indolepyruvate ferredoxin oxidoreductase from the hyperthermophilic archaeon Pyrococcus furiosus - a new enzyme involved in peptide fermentation. J. Biol. Chem. 269 (1994) 16726–16732. [PMID: 8206994]
2.  Siddiqui, M.A., Fujiwara, S. and Imanaka, T. Indolepyruvate ferredoxin oxidoreductase from Pyrococcus sp. K0d1 possesses a mosaic: Structure showing features of various oxidoreductases. Mol. Gen. Genet. 254 (1997) 433–439. [PMID: 9180697]
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 1.2.7.8 created 2003]
 
 
EC 1.2.7.11     
Accepted name: 2-oxoacid oxidoreductase (ferredoxin)
Reaction: a 2-oxocarboxylate + CoA + 2 oxidized ferredoxin = an acyl-CoA + CO2 + 2 reduced ferredoxin + 2 H+
Other name(s): OFOR
Systematic name: 2-oxocarboxylate:ferredoxin 2-oxidoreductase (decarboxylating, CoA-acylating)
Comments: Contains thiamine diphosphate and [4Fe-4S] clusters [2]. This enzyme is a member of the 2-oxoacid oxidoreductases, a family of enzymes that oxidatively decarboxylate different 2-oxoacids to form their CoA derivatives, and are differentiated based on their substrate specificity. For example, see EC 1.2.7.3, 2-oxoglutarate synthase and EC 1.2.7.7, 3-methyl-2-oxobutanoate dehydrogenase (ferredoxin).
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB
References:
1.  Kerscher, L. and Oesterhelt, D. Purification and properties of two 2-oxoacid:ferredoxin oxidoreductases from Halobacterium halobium. Eur. J. Biochem. 116 (1981) 587–594. [DOI] [PMID: 6266826]
2.  Zhang, Q., Iwasaki, T., Wakagi, T. and Oshima, T. 2-oxoacid:ferredoxin oxidoreductase from the thermoacidophilic archaeon, Sulfolobus sp. strain 7. J. Biochem. 120 (1996) 587–599. [PMID: 8902625]
3.  Fukuda, E., Kino, H., Matsuzawa, H. and Wakagi, T. Role of a highly conserved YPITP motif in 2-oxoacid:ferredoxin oxidoreductase: heterologous expression of the gene from Sulfolobus sp.strain 7, and characterization of the recombinant and variant enzymes. Eur. J. Biochem. 268 (2001) 5639–5646. [DOI] [PMID: 11683888]
4.  Fukuda, E. and Wakagi, T. Substrate recognition by 2-oxoacid:ferredoxin oxidoreductase from Sulfolobus sp. strain 7. Biochim. Biophys. Acta 1597 (2002) 74–80. [DOI] [PMID: 12009405]
5.  Nishizawa, Y., Yabuki, T., Fukuda, E. and Wakagi, T. Gene expression and characterization of two 2-oxoacid:ferredoxin oxidoreductases from Aeropyrum pernix K1. FEBS Lett. 579 (2005) 2319–2322. [DOI] [PMID: 15848165]
6.  Park, Y.J., Yoo, C.B., Choi, S.Y. and Lee, H.B. Purifications and characterizations of a ferredoxin and its related 2-oxoacid:ferredoxin oxidoreductase from the hyperthermophilic archaeon, Sulfolobus solfataricus P1. J. Biochem. Mol. Biol. 39 (2006) 46–54. [PMID: 16466637]
[EC 1.2.7.11 created 2013]
 
 
EC 1.4.1.8     
Accepted name: valine dehydrogenase (NADP+)
Reaction: L-valine + H2O + NADP+ = 3-methyl-2-oxobutanoate + NH3 + NADPH + H+
Other name(s): valine dehydrogenase (nicotinanide adenine dinucleotide phosphate); valine dehydrogenase (NADP)
Systematic name: L-valine:NADP+ oxidoreductase (deaminating)
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 37255-39-3
References:
1.  Kagan, Z.S., Kretovich, V.L. and Polyakov, V.A. Biosynthesis of valine by reductive amination of its keto analogue in plants. Enzymologia 30 (1966) 343–366. [PMID: 6005410]
2.  Kagan, Z.S., Polyakov, V.A. and Kretovich, V.L. Soluble valine dehydrogenase from roots of plant seedings. Biochemistry (Mosc.) 33 (1968) 74–84. [PMID: 4385962]
3.  Kagan, Z.S., Polyakov, V.A. and Kretovich, V.L. Purification and properties of valine dehydrogenase. Biochemistry (Mosc.) 34 (1969) 47–51. [PMID: 4389825]
[EC 1.4.1.8 created 1972]
 
 
EC 1.4.1.23     
Accepted name: valine dehydrogenase (NAD+)
Reaction: L-valine + H2O + NAD+ = 3-methyl-2-oxobutanoate + NH3 + NADH + H+
Systematic name: L-valine:NAD+ oxidoreductase (deaminating)
Comments: The enzyme from Streptomyces spp. has no activity with NADP+ [cf. EC 1.4.1.8, valine dehydrogenase (NADP+)].
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Vancurová, I., Vancura, A., Volc, J., Neuzil, J., Flieger, M., Basarová, G. and Behal, V. Isolation and characterization of valine dehydrogenase from Streptomyces aureofaciens. J. Bacteriol. 170 (1988) 5192–5196. [DOI] [PMID: 3182727]
2.  Navarrete, R.M., Vara, J.A. and Hutchinson, C.R. Purification of an inducible L-valine dehydrogenase of Streptomyces coelicolor A3(2). J. Gen. Microbiol. 136 (1990) 273–281. [DOI] [PMID: 2324704]
[EC 1.4.1.23 created 2012]
 
 
EC 1.8.1.4     
Accepted name: dihydrolipoyl dehydrogenase
Reaction: protein N6-(dihydrolipoyl)lysine + NAD+ = protein N6-(lipoyl)lysine + NADH + H+
For diagram of glycine cleavage system, click here, for diagram of the citric acid cycle, click here and for diagram of oxo-acid dehydrogenase complexes, click here
Glossary: dihydrolipoyl = (6R)-6,8-disulfanyloctanoyl
For structure of dihydrolipoyl, click here
Other name(s): LDP-Glc; LDP-Val; dehydrolipoate dehydrogenase; diaphorase; dihydrolipoamide dehydrogenase; dihydrolipoamide:NAD+ oxidoreductase; dihydrolipoic dehydrogenase; dihydrothioctic dehydrogenase; lipoamide dehydrogenase (NADH); lipoamide oxidoreductase (NADH); lipoamide reductase; lipoamide reductase (NADH); lipoate dehydrogenase; lipoic acid dehydrogenase; lipoyl dehydrogenase; protein-6-N-(dihydrolipoyl)lysine:NAD+ oxidoreductase
Systematic name: protein-N6-(dihydrolipoyl)lysine:NAD+ oxidoreductase
Comments: A flavoprotein (FAD). A component of the multienzyme 2-oxo-acid dehydrogenase complexes. In the pyruvate dehydrogenase complex, it binds to the core of EC 2.3.1.12, dihydrolipoyllysine-residue acetyltransferase, and catalyses oxidation of its dihydrolipoyl groups. It plays a similar role in the oxoglutarate and 3-methyl-2-oxobutanoate dehydrogenase complexes. Another substrate is the dihydrolipoyl group in the H-protein of the glycine-cleavage system (click here for diagram), in which it acts, together with EC 1.4.4.2, glycine dehydrogenase (decarboxylating), and EC 2.1.2.10, aminomethyltransferase, to break down glycine. It can also use free dihydrolipoate, dihydrolipoamide or dihydrolipoyllysine as substrate. This enzyme was first shown to catalyse the oxidation of NADH by methylene blue; this activity was called diaphorase. The glycine cleavage system is composed of four components that only loosely associate: the P protein (EC 1.4.4.2), the T protein (EC 2.1.2.10), the L protein (EC 1.8.1.4) and the lipoyl-bearing H protein [6].
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 9001-18-7
References:
1.  Massey, V. Lipoyl dehydrogenase. In: Boyer, P.D., Lardy, H. and Myrbäck, K. (Ed.), The Enzymes, 2nd edn, vol. 7, Academic Press, New York, 1963, pp. 275–306.
2.  Massey, V., Gibson, Q.H. and Veeger, C. Intermediates in the catalytic action of lipoyl dehydrogenase (diaphorase). Biochem. J. 77 (1960) 341–351. [PMID: 13767908]
3.  Savage, N. Preparation and properties of highly purified diaphorase. Biochem. J. 67 (1957) 146–155. [PMID: 13471525]
4.  Straub, F.B. Isolation and properties of a flavoprotein from heart muscle tissue. Biochem. J. 33 (1939) 787–792. [PMID: 16746974]
5.  Perham, R.N. Swinging arms and swinging domains in multifunctional enzymes: catalytic machines for multistep reactions. Annu. Rev. Biochem. 69 (2000) 961–1004. [DOI] [PMID: 10966480]
6.  Nesbitt, N.M., Baleanu-Gogonea, C., Cicchillo, R.M., Goodson, K., Iwig, D.F., Broadwater, J.A., Haas, J.A., Fox, B.G. and Booker, S.J. Expression, purification, and physical characterization of Escherichia coli lipoyl(octanoyl)transferase. Protein Expr. Purif. 39 (2005) 269–282. [DOI] [PMID: 15642479]
[EC 1.8.1.4 created 1961 as EC 1.6.4.3, modified 1976, transferred 1983 to EC 1.8.1.4, modified 2003, modified 2006]
 
 
EC 2.1.2.11     
Accepted name: 3-methyl-2-oxobutanoate hydroxymethyltransferase
Reaction: 5,10-methylenetetrahydrofolate + 3-methyl-2-oxobutanoate + H2O = tetrahydrofolate + 2-dehydropantoate
For diagram of the early stages of CoA biosynthesis, click here
Other name(s): α-ketoisovalerate hydroxymethyltransferase; dehydropantoate hydroxymethyltransferase; ketopantoate hydroxymethyltransferase; oxopantoate hydroxymethyltransferase; 5,10-methylene tetrahydrofolate:α-ketoisovalerate hydroxymethyltransferase
Systematic name: 5,10-methylenetetrahydrofolate:3-methyl-2-oxobutanoate hydroxymethyltransferase
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 56093-17-5
References:
1.  Powers, S.G. and Snell, E.E. Ketopantoate hydroxymethyltransferase. II. Physical, catalytic, and regulatory properties. J. Biol. Chem. 251 (1976) 3786–3793. [PMID: 6463]
2.  Teller, J.H., Powers, S.G. and Snell, E.E. Ketopantoate hydroxymethyltransferase. I. Purification and role in pantothenate biosynthesis. J. Biol. Chem. 251 (1976) 3780–3785. [PMID: 776976]
[EC 2.1.2.11 created 1982]
 
 
EC 2.3.1.168     
Accepted name: dihydrolipoyllysine-residue (2-methylpropanoyl)transferase
Reaction: 2-methylpropanoyl-CoA + enzyme N6-(dihydrolipoyl)lysine = CoA + enzyme N6-(S-[2-methylpropanoyl]dihydrolipoyl)lysine
For diagram of oxo-acid-dehydrogenase complexes, click here
Glossary: dihydrolipoyl group
Other name(s): dihydrolipoyl transacylase; enzyme-dihydrolipoyllysine:2-methylpropanoyl-CoA S-(2-methylpropanoyl)transferase; 2-methylpropanoyl-CoA:enzyme-6-N-(dihydrolipoyl)lysine S-(2-methylpropanoyl)transferase
Systematic name: 2-methylpropanoyl-CoA:enzyme-N6-(dihydrolipoyl)lysine S-(2-methylpropanoyl)transferase
Comments: A multimer (24-mer) of this enzyme forms the core of the multienzyme 3-methyl-2-oxobutanoate dehydrogenase complex, and binds tightly both EC 1.2.4.4, 3-methyl-2-oxobutanoate dehydrogenase (2-methylpropanoyl-transferring) and EC 1.8.1.4, dihydrolipoyl dehydrogenase. The lipoyl group of this enzyme is reductively 2-methylpropanoylated by EC 1.2.4.4, and the only observed direction catalysed by EC 2.3.1.168 is that where this 2-methylpropanoyl is passed to coenzyme A. In addition to the 2-methylpropanoyl group, formed when EC 1.2.4.4 acts on the oxoacid that corresponds with valine, this enzyme also transfers the 3-methylbutanoyl and S-2-methylbutanoyl groups, donated to it when EC 1.2.4.4 acts on the oxo acids corresponding with leucine and isoleucine.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 102784-26-9
References:
1.  Massey, L.K., Sokatch, J.R. and Conrad, R.S. Branched-chain amino acid catabolism in bacteria. Bacteriol. Rev. 40 (1976) 42–54. [PMID: 773366]
2.  Chuang, D.T., Hu, C.C., Ku, L.S., Niu, W.L., Myers, D.E. and Cox, R.P. Catalytic and structural properties of the dihydrolipoyl transacylase component of bovine branched-chain α-keto acid dehydrogenase. J. Biol. Chem. 259 (1984) 9277–9284. [PMID: 6746648]
3.  Wynn, R.M., Davie, J.R., Zhi, W., Cox, R.P. and Chuang, D.T. In vitro reconstitution of the 24-meric E2 inner core of bovine mitochondrial branched-chain α-keto acid dehydrogenase complex: requirement for chaperonins GroEL and GroES. Biochemistry 33 (1994) 8962–8968. [PMID: 7913832]
4.  Perham, R.N. Swinging arms and swinging domains in multifunctional enzymes: catalytic machines for multistep reactions. Annu. Rev. Biochem. 69 (2000) 961–1004. [DOI] [PMID: 10966480]
[EC 2.3.1.168 created 2003]
 
 
EC 2.3.1.182      
Transferred entry: (R)-citramalate synthase. Now classified as EC 2.3.3.21, (R)-citramalate synthase.
[EC 2.3.1.182 created 2007, deleted 2021]
 
 
EC 2.3.3.13     
Accepted name: 2-isopropylmalate synthase
Reaction: acetyl-CoA + 3-methyl-2-oxobutanoate + H2O = (2S)-2-isopropylmalate + CoA
For diagram of leucine-biosynthesis pathway, click here
Other name(s): 3-carboxy-3-hydroxy-4-methylpentanoate 3-methyl-2-oxobutanoate-lyase (CoA-acetylating); α-isopropylmalate synthetase; α-isopropylmalate synthase; α-isopropylmalic synthetase; isopropylmalate synthase; isopropylmalate synthetase
Systematic name: acetyl-CoA:3-methyl-2-oxobutanoate C-acetyltransferase (thioester-hydrolysing, carboxymethyl-forming)
Comments: Requires K+.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 9030-98-2
References:
1.  Kohlhaw, G., Leary, T.R. and Umbarger, H.E. α-Isopropylmalate synthase from Salmonella typhimurium. Purification and properties. J. Biol. Chem. 244 (1969) 2218–2225. [PMID: 4976555]
2.  Webster, R.E. and Gross, S.R. The α-isopropylmalate synthetase of Neurospora. I. The kinetics and end product control of α-isopropylmalate synthetase function. Biochemistry 4 (1965) 2309–2327.
3.  Cole, F.E., Kalyanpur, M. G. and Stevens, C. M. Absolute configuration of α-isopropylmalate and the mechanism of its conversion to β-isopropylmalate in the biosynthesis of leucine. Biochemistry 12 (1973) 3346–3350. [PMID: 4270046]
[EC 2.3.3.13 created 1972 as EC 4.1.3.12, transferred 2002 to EC 2.3.3.13]
 
 
EC 2.3.3.21     
Accepted name: (R)-citramalate synthase
Reaction: acetyl-CoA + pyruvate + H2O = CoA + (2R)-2-hydroxy-2-methylbutanedioate
Glossary: (2R)-2-hydroxy-2-methylbutanedioate = (2R)-2-methylmalate = (–)-citramalate
3-methyl-2-oxobutanoate = α-ketoisovalerate
2-oxobutanoate = α-ketobutyrate
4-methyl-2-oxopentanoate = α-ketoisocaproate
2-oxohexanoate = α-ketopimelate
2-oxoglutarate = α-ketoglutarate
Other name(s): CimA
Comments: One of the enzymes involved in a pyruvate-derived pathway for isoleucine biosynthesis that is found in some bacterial and archaeal species [1,2]. The enzyme can be inhibited by isoleucine, the end-product of the pathway, but not by leucine [2]. The enzyme is highly specific for pyruvate as substrate, as the 2-oxo acids 3-methyl-2-oxobutanoate, 2-oxobutanoate, 4-methyl-2-oxopentanoate, 2-oxohexanoate and 2-oxoglutarate cannot act as substrate [1,2].
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Howell, D.M., Xu, H. and White, R.H. (R)-citramalate synthase in methanogenic archaea. J. Bacteriol. 181 (1999) 331–333. [DOI] [PMID: 9864346]
2.  Xu, H., Zhang, Y., Guo, X., Ren, S., Staempfli, A.A., Chiao, J., Jiang, W. and Zhao, G. Isoleucine biosynthesis in Leptospira interrogans serotype 1ai strain 56601 proceeds via a threonine-independent pathway. J. Bacteriol. 186 (2004) 5400–5409. [DOI] [PMID: 15292141]
[EC 2.3.3.21 created 2007 as EC 2.3.1.182, transferred 2021 to EC 2.3.3.21]
 
 
EC 2.6.1.32     
Accepted name: valine—3-methyl-2-oxovalerate transaminase
Reaction: L-valine + (S)-3-methyl-2-oxopentanoate = 3-methyl-2-oxobutanoate + L-isoleucine
For diagram of EC 2.6.1, click here
Other name(s): valine—isoleucine transaminase; valine-3-methyl-2-oxovalerate aminotransferase; alanine-valine transaminase; valine-2-keto-methylvalerate aminotransferase; valine-isoleucine aminotransferase
Systematic name: L-valine:(S)-3-methyl-2-oxopentanoate aminotransferase
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 9023-14-7
References:
1.  Kagan, Z.S., Dronov, A.S. and Kretovich, V.L. [Some properties of valine-isoleucine- and valine-glutamate-aminotransferases of pea sprouts.] Dokl. Akad. Nauk S.S.S.R. 179 (1968) 1236–1239. (in Russian)
[EC 2.6.1.32 created 1972, modified 1976]
 
 
EC 2.6.1.66     
Accepted name: valine—pyruvate transaminase
Reaction: L-valine + pyruvate = 3-methyl-2-oxobutanoate + L-alanine
For diagram of reaction, click here, of isoleucine and valine biosynthesis, click here and for diagram of mechanism, click here
Other name(s): transaminase C; valine-pyruvate aminotransferase; alanine-oxoisovalerate aminotransferase
Systematic name: L-valine:pyruvate aminotransferase
Comments: Different from EC 2.6.1.42, branched-chain-amino-acid-transaminase.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 73379-50-7
References:
1.  Falkinham, J.O. , III Identification of a mutation affecting an alanine-α-ketoisovalerate transaminase activity in Escherichia coli K-12. Mol. Gen. Genet. 176 (1979) 147–149. [PMID: 396446]
2.  Rudman, D. and Meister, A. Transamination in Escherichia coli. J. Biol. Chem. 200 (1953) 591–604. [PMID: 13034817]
[EC 2.6.1.66 created 1984]
 
 
EC 2.7.1.37      
Transferred entry: protein kinase. Now divided into EC 2.7.11.1 (non-specific serine/threonine protein kinase), EC 2.7.11.8 (Fas-activated serine/threonine kinase), EC 2.7.11.9 (Goodpasture-antigen-binding protein kinase), EC 2.7.11.10 (IκB kinase), EC 2.7.11.11 (cAMP-dependent protein kinase), EC 2.7.11.12 (cGMP-dependent protein kinase), EC 2.7.11.13 (protein kinase C), EC 2.7.11.21 (polo kinase), EC 2.7.11.22 (cyclin-dependent kinase), EC 2.7.11.24 (mitogen-activated protein kinase), EC 2.7.11.25 (mitogen-activated protein kinase kinase kinase), EC 2.7.11.30 (receptor protein serine/threonine kinase) and EC 2.7.12.1 (dual-specificity kinase)
[EC 2.7.1.37 created 1961 (EC 2.7.1.70 incorporated 2004), deleted 2005]
 
 
EC 2.7.1.115      
Transferred entry: [3-methyl-2-oxobutanoate dehydrogenase (lipoamide)] kinase. Now EC 2.7.11.4, [3-methyl-2-oxobutanoate dehydrogenase (acetyl-transferring)] kinase
[EC 2.7.1.115 created 1986, deleted 2005]
 
 
EC 2.7.11.4     
Accepted name: [3-methyl-2-oxobutanoate dehydrogenase (acetyl-transferring)] kinase
Reaction: ATP + [3-methyl-2-oxobutanoate dehydrogenase (acetyl-transferring)] = ADP + [3-methyl-2-oxobutanoate dehydrogenase (acetyl-transferring)] phosphate
Other name(s): BCK; BCKD kinase; BCODH kinase; branched-chain α-ketoacid dehydrogenase kinase; branched-chain 2-oxo acid dehydrogenase kinase; branched-chain keto acid dehydrogenase kinase; branched-chain oxo acid dehydrogenase kinase (phosphorylating); STK2
Systematic name: ATP:[3-methyl-2-oxobutanoate dehydrogenase (acetyl-transferring)] phosphotransferase
Comments: The enzyme has no activating compound but is specific for its substrate. It is a mitochondrial enzyme associated with the branched-chain 2-oxoacid dehydrogenase complex. Phosphorylation inactivates EC 1.2.4.4, 3-methyl-2-oxobutanoate dehydrogenase (2-methylpropanoyl-transferring).
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 82391-38-6
References:
1.  Paxton, R. and Harris, R.A. Isolation of rabbit liver branched chain α-ketoacid dehydrogenase and regulation by phosphorylation. J. Biol. Chem. 257 (1982) 14433–14439. [PMID: 7142221]
2.  Wynn, R.M., Chuang, J.L., Cote, C.D. and Chuang, D.T. Tetrameric assembly and conservation in the ATP-binding domain of rat branched-chain α-ketoacid dehydrogenase kinase. J. Biol. Chem. 275 (2000) 30512–30519. [DOI] [PMID: 10903321]
3.  Chuang, J.L., Wynn, R.M. and Chuang, D.T. The C-terminal hinge region of lipoic acid-bearing domain of E2b is essential for domain interaction with branched-chain α-keto acid dehydrogenase kinase. J. Biol. Chem. 277 (2002) 36905–36908. [DOI] [PMID: 12189132]
4.  Popov, K.M., Hawes, J.W. and Harris, R.A. Mitochondrial α-ketoacid dehydrogenase kinases: a new family of protein kinases. Adv. Second Messenger Phosphoprotein Res. 31 (1997) 105–111. [PMID: 9344245]
[EC 2.7.11.4 created 1986 as EC 2.7.1.115, transferred 2005 to EC 2.7.11.4]
 
 
EC 3.1.3.52     
Accepted name: [3-methyl-2-oxobutanoate dehydrogenase (2-methylpropanoyl-transferring)]-phosphatase
Reaction: [3-methyl-2-oxobutanoate dehydrogenase (2-methylpropanoyl-transferring)] phosphate + H2O = [3-methyl-2-oxobutanoate dehydrogenase (2-methylpropanoyl-transferring)] + phosphate
Glossary: lipoyl group
Other name(s): branched-chain oxo-acid dehydrogenase phosphatase; branched-chain 2-keto acid dehydrogenase phosphatase; branched-chain α-keto acid dehydrogenase phosphatase; BCKDH (ambiguous); [3-methyl-2-oxobutanoate dehydrogenase (lipoamide)]-phosphatase; [3-methyl-2-oxobutanoate dehydrogenase (lipoamide)]-phosphate phosphohydrolase
Systematic name: [3-methyl-2-oxobutanoate dehydrogenase (2-methylpropanoyl-transferring)]-phosphate phosphohydrolase
Comments: A mitochondrial enzyme associated with the 3-methyl-2-oxobutanoate dehydrogenase complex. Simultaneously dephosphorylates and activates EC 1.2.4.4 3-methyl-2-oxobutanoate dehydrogenase (2-methylpropanoyl-transferring), that has been inactivated by phosphorylation.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 87244-20-0, 88086-29-7
References:
1.  Fatania, H.R., Patston, P.A. and Randle, P.J. Dephosphorylation and reactivation of phosphorylated purified ox-kidney branched-chain dehydrogenase complex by co-purified phosphatase. FEBS Lett. 158 (1983) 234–238. [DOI] [PMID: 6307746]
2.  Reed, L.J., Damuni, Z. and Merryfield, M.L. Regulation of mammalian pyruvate and branched-chain α-keto acid dehydrogenase complexes by phosphorylation-dephosphorylation. Curr. Top. Cell. Regul. 27 (1985) 41–49. [DOI] [PMID: 3004826]
[EC 3.1.3.52 created 1986]
 
 
EC 4.1.2.12     
Accepted name: 2-dehydropantoate aldolase
Reaction: 2-dehydropantoate = 3-methyl-2-oxobutanoate + formaldehyde
Glossary: pantoate = 2,4-dihydroxy-3,3-dimethylbutanoate
Other name(s): ketopantoaldolase; 2-dehydropantoate formaldehyde-lyase
Systematic name: 2-dehydropantoate formaldehyde-lyase (3-methyl-2-oxobutanoate-forming)
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 9024-51-5
References:
1.  McIntosh, E.N., Purko, M. and Wood, W.A. Ketopantoate formation by a hydroxymethylation enzyme from Escherichia coli. J. Biol. Chem. 228 (1957) 499–510. [PMID: 13475336]
[EC 4.1.2.12 created 1965, modified 2002]
 
 
EC 4.2.1.9     
Accepted name: dihydroxy-acid dehydratase
Reaction: 2,3-dihydroxy-3-methylbutanoate = 3-methyl-2-oxobutanoate + H2O
For diagram of isoleucine and valine biosynthesis, click here
Other name(s): acetohydroxyacid dehydratase; α,β-dihydroxyacid dehydratase; 2,3-dihydroxyisovalerate dehydratase; α,β-dihydroxyisovalerate dehydratase; dihydroxy acid dehydrase; DHAD; 2,3-dihydroxy-acid hydro-lyase
Systematic name: 2,3-dihydroxy-3-methylbutanoate hydro-lyase (3-methyl-2-oxobutanoate-forming)
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 9024-32-2
References:
1.  Kanamori, M. and Wixom, R.L. Studies in valine biosynthesis. V. Characteristics of the purified dihydroxyacid dehydratase from spinach leaves. J. Biol. Chem. 238 (1963) 998–1005. [PMID: 13962154]
2.  Myers, J.W. Dihydroxy acid dehydrase: an enzyme involved in the biosynthesis of isoleucine and valine. J. Biol. Chem. 236 (1961) 1414–1418. [PMID: 13727223]
[EC 4.2.1.9 created 1961]
 
 
EC 5.4.99.3     
Accepted name: 2-acetolactate mutase
Reaction: 2-acetolactate = 3-hydroxy-3-methyl-2-oxobutanoate
Other name(s): acetolactate mutase; acetohydroxy acid isomerase
Systematic name: 2-acetolactate methylmutase
Comments: Requires ascorbic acid; also converts 2-aceto-2-hydroxybutanoate to 3-hydroxy-3-methyl-2-oxopentanoate.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 37318-52-8
References:
1.  Allaudeen, H.S. and Ramakrishnan, T. Biosynthesis of isoleucine and valine in Mycobacterium tuberculosis H37 Rv. Arch. Biochem. Biophys. 125 (1968) 199–209. [DOI] [PMID: 4384955]
[EC 5.4.99.3 created 1972]
 
 


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