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EC 1.2.4.4 Details

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EC number

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

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)

CAS registry number

9082-72-8

Comment

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.

History

created 1972 (EC 1.2.4.3 created 1972, incorporated 1978), modified 2003

EC Tree

1 Oxidoreductases

1.1 Acting on the CH-OH group of donors

1.2 Acting on the aldehyde or oxo group of donors

1.2.1 With NAD⁺ or NADP⁺ as acceptor

1.2.2 With a cytochrome as acceptor

1.2.3 With oxygen as acceptor

1.2.4 With a disulfide as acceptor

1.2.5 With a quinone or similar compound as acceptor

1.2.7 With an iron-sulfur protein as acceptor

1.2.98 With other, known, physiological acceptors

1.2.99 With unknown physiological acceptors

1.2.99.1 created 1961, deleted 1984

1.2.99.2 carbon-monoxide dehydrogenase (acceptor)

1.2.99.3 aldehyde dehydrogenase (pyrroloquinoline-quinone)

1.2.99.4 formaldehyde dismutase

1.2.99.5 formylmethanofuran dehydrogenase

1.2.99.6 carboxylate reductase

1.2.99.7 aldehyde dehydrogenase (FAD-independent)

1.2.99.8 glyceraldehyde dehydrogenase (FAD-containing)

1.2.99.9 formate dehydrogenase (coenzyme F₄₂₀)

1.2.99.10 4,4′-diapolycopenoate synthase

1.3 Acting on the CH-CH group of donors

1.4 Acting on the CH-NH₂ group of donors

1.5 Acting on the CH-NH group of donors

1.6 Acting on NADH or NADPH

1.7 Acting on other nitrogenous compounds as donors

1.8 Acting on a sulfur group of donors

1.9 Acting on a heme group of donors

1.10 Acting on diphenols and related substances as donors

1.11 Acting on a peroxide as acceptor

1.12 Acting on hydrogen as donor

1.12.1 With NAD⁺ or NADP⁺ as acceptor

1.12.2 With a cytochrome as acceptor

1.12.5 With a quinone or similar compound as acceptor

1.12.7 With an iron-sulfur protein as acceptor

1.12.98 With other, known, physiological acceptors

1.12.99 With unknown physiological acceptors

1.13 Acting on single donors with incorporation of molecular oxygen (oxygenases)

1.14 Acting on paired donors, with incorporation or reduction of molecular oxygen

1.15 Acting on superoxide as acceptor

1.16 Oxidizing metal ions

1.17 Acting on CH or CH₂ groups

1.18 Acting on iron-sulfur proteins as donors

1.19 Acting on reduced flavodoxin as donor

1.20 Acting on phosphorus or arsenic in donors

1.21 Catalysing the reaction X-H + Y-H = X-Y

1.21.1 With NAD⁺ or NADP⁺ as acceptor

1.21.3 With oxygen as acceptor

1.21.4 With a disulfide as acceptor

1.21.98 With other, known, physiological acceptors

1.21.99 With unknown physiological acceptors

1.22 Acting on halogen in donors

1.23 Reducing C-O-C group as acceptor

1.97 Other oxidoreductases

1.98 Enzymes using H₂ as reductant (deleted subclass)

1.99 Other enzymes using O₂ as oxidant (deleted subclass)

2 Transferases

2.1 Transferring one-carbon groups

2.2 Transferring aldehyde or ketonic groups

2.3 Acyltransferases

2.4 Glycosyltransferases

2.5 Transferring alkyl or aryl groups, other than methyl groups

2.6 Transferring nitrogenous groups

2.7 Transferring phosphorus-containing groups

2.8 Transferring sulfur-containing groups

2.9 Transferring selenium-containing groups

2.10 Transferring molybdenum- or tungsten-containing groups