Any feedback?
Please rate this page
(literature.php)
(0/150)

BRENDA support

Literature summary for 1.1.1.86 extracted from

  • Leung, E.W.; Guddat, L.W.
    Conformational changes in a plant ketol-acid reductoisomerase upon Mg2+ and NADPH binding as revealed by two crystal structures (2009), J. Mol. Biol., 389, 167-182.
    View publication on PubMed

Cloned(Commentary)

Cloned (Comment) Organism
overexpression in Escherichia coli strain BL21(DE3) Oryza sativa

Crystallization (Commentary)

Crystallization (Comment) Organism
enzyme KARI in complex with Mg2+ or with Mg2+ and NADPH, hanging-drop method by vaporphase diffusion at 18°C, 0.003 ml of protein solution containing 6 mg/ml enzyme, 50 mM Hepes, pH 7.5, 5 mM NADPH, and 5 mM MgCl2, is mixed with 0.001 ml of reservoir solution containing 0.2 M magnesium chloride hexahydrate, 0.1 M Tris-HCl, pH 8.5, and 15% w/v PEG 4000, a few days to 3 months, X-ray diffraction structure determination and analysis at 1.55 A and 2.80 A resolution, respectively, molecular replacement Oryza sativa

Inhibitors

Inhibitors Comment Organism Structure
ethylene glycol exhibits competitive and uncompetitive inhibition Oryza sativa

Metals/Ions

Metals/Ions Comment Organism Structure
Mg2+ required for the alkyl migration reaction, Km is 0.0072 mM, binding structure, overview Oryza sativa
additional information the enzyme catalyzes a two-step reaction: an alkyl migration that requires Mg2+, and a reduction reaction involving NADPH. For the reduction reaction, a divalent metal ion is also required, with any of Mg2+, Mn2+, Co2+, or Ni2+ utilized in this role Oryza sativa

Natural Substrates/ Products (Substrates)

Natural Substrates Organism Comment (Nat. Sub.) Natural Products Comment (Nat. Pro.) Rev. Reac.
(R)-2,3-dihydroxy-3-methylbutanoate + NADP+ Oryza sativa
-
(S)-2-hydroxy-2-methyl-3-oxobutanoate + NADPH + H+
-
r

Organism

Organism UniProt Comment Textmining
Oryza sativa Q65XK0
-
-

Reaction

Reaction Comment Organism Reaction ID
(2R)-2,3-dihydroxy-3-methylbutanoate + NADP+ = (2S)-2-hydroxy-2-methyl-3-oxobutanoate + NADPH + H+ active site structure and catalytic mechanism, mechanism of induced fit, overview Oryza sativa

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
(R)-2,3-dihydroxy-3-methylbutanoate + NADP+
-
Oryza sativa (S)-2-hydroxy-2-methyl-3-oxobutanoate + NADPH + H+
-
r
(R)-2,3-dihydroxy-3-methylbutanoate + NADP+ conformational changes in a plant ketol-acid reductoisomerase upon Mg2+ and NADPH binding, overview Oryza sativa (S)-2-hydroxy-2-methyl-3-oxobutanoate + NADPH + H+
-
r
2-aceto-2-hydroxybutyrate + NADP+
-
Oryza sativa (2R,3R)-2,3-dihydroxy-3-methylvalerate + NADPH + H+
-
r
2-acetolactate + NADP+
-
Oryza sativa (2R)-2,3-dihydroxy-3-isovalerate + NADPH + H+
-
r
additional information KARI catalyzes two reactions: alkyl migration and reduction. Structure-function relationship, effects of ligand binding, MG2+ and NADPH, on the enzyme conformation, overview Oryza sativa ?
-
?

Subunits

Subunits Comment Organism
dimer structure-function relationship, effects of ligand, Mg2+ and NADPH, binding on the enzyme conformation, overview Oryza sativa

Synonyms

Synonyms Comment Organism
KARI
-
Oryza sativa

Temperature Optimum [°C]

Temperature Optimum [°C] Temperature Optimum Maximum [°C] Comment Organism
30
-
assay at Oryza sativa

pH Optimum

pH Optimum Minimum pH Optimum Maximum Comment Organism
8
-
assay at Oryza sativa

Cofactor

Cofactor Comment Organism Structure
NADP+
-
Oryza sativa
NADPH required, the majority of the NADP+ molecule binds to the N-domain of KARI with polar contacts with 11 residues, including W133, G134, S135, Q136, R162, S165, S167, S201, D202, Q205, and G254. There are also contacts with the C-domain, although these are much fewer and involve only the phosphoryl oxygen atoms and the oxygen and nitrogen atoms of the nicotinamide group in NADPH, forming contacts with C517, S518, and T519, and with R589 in the polypeptide Oryza sativa

Ki Value [mM]

Ki Value [mM] Ki Value maximum [mM] Inhibitor Comment Organism Structure
0.0025
-
ethylene glycol pH 8.0, 30°C, recombinant enzyme, competitive mode Oryza sativa
0.0032
-
ethylene glycol pH 8.0, 30°C, recombinant enzyme, uncompetitive mode Oryza sativa

General Information

General Information Comment Organism
metabolism the enzyme is involved in the branched-chain amino acid biosynthesis pathway Oryza sativa