ExplorEnz: EC 1.1.1.85

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1.1.1.85

Accepted name:

3-isopropylmalate dehydrogenase

Reaction:

(2R,3S)-3-isopropylmalate + NAD⁺ = 4-methyl-2-oxopentanoate + CO₂ + NADH + H⁺ (overall reaction)
(1a) (2R,3S)-3-isopropylmalate + NAD⁺ = (2S)-2-isopropyl-3-oxosuccinate + NADH + H⁺
(1b) (2S)-2-isopropyl-3-oxosuccinate = 4-methyl-2-oxopentanoate + CO₂ (spontaneous)

For diagram of leucine biosynthesis, click here

Other name(s):

β-isopropylmalic enzyme; β-isopropylmalate dehydrogenase; threo-D_s-3-isopropylmalate dehydrogenase; 3-carboxy-2-hydroxy-4-methylpentanoate:NAD⁺ oxidoreductase

Systematic name:

(2R,3S)-3-isopropylmalate:NAD⁺ oxidoreductase

Comments:

The product decarboxylates spontaneously to yield 4-methyl-2-oxopentanoate.

Links to other databases:

BRENDA, EXPASY, Gene, KEGG, MetaCyc, PDB, CAS registry number: 9030-97-1

References:

1.	Burns, R.O., Umbarger, H.E. and Gross, S.R. The biosynthesis of leucine. III. The conversion of α-hydroxy-β-carboxyisocaproate to α-ketoisocaproate. Biochemistry 2 (1963) 1053. [PMID: 14087358]
2.	Parsons, S.J. and Burns, R.O. Purification and properties of β-isopropylmalate dehydrogenase. J. Biol. Chem. 244 (1969) 996–1003. [PMID: 4889950]
3.	Németh, A., Svingor, Á., Pócsik, M., Dobó, J., Magyar, C, Szilaaagyi, A., Gál, P. and Závodszky, P. Mirror image mutations reveal the significance of an intersubunit ion cluster in the stability of 3-isopropylmalate dehydrogenase. FEBS Lett. 468 (2000) 48–52. [DOI] [PMID: 10683439]
4.	Calvo, J. M., Stevens, C. M., Kalyanpur, M. G., and Umbarger, H. E. The absolute configuration of α-hydroxy-β-carboxyisocaproic acid (3-isopropylmalic acid), an intermediate in leucine biosynthesis. Biochemistry 3 (1964) 2024–2027. [PMID: 14269331]

[EC 1.1.1.85 created 1972, modified 1976]