Information on EC 1.1.1.382 - ketol-acid reductoisomerase (NAD+)

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The expected taxonomic range for this enzyme is: Bacteria, Archaea

EC NUMBER
COMMENTARY hide
1.1.1.382
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RECOMMENDED NAME
GeneOntology No.
ketol-acid reductoisomerase (NAD+)
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REACTION
REACTION DIAGRAM
COMMENTARY hide
ORGANISM
UNIPROT
LITERATURE
(2R)-2,3-dihydroxy-3-methylbutanoate + NAD+ = (2S)-2-hydroxy-2-methyl-3-oxobutanoate + NADH + H+
show the reaction diagram
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SYSTEMATIC NAME
IUBMB Comments
(2R)-2,3-dihydroxy-3-methylbutanoate:NAD+ oxidoreductase (isomerizing)
The enzyme, characterized from the bacteria Thermacetogenium phaeum and Desulfococcus oleovorans and from the archaeon Archaeoglobus fulgidus, is specific for NADH [cf. EC 1.1.1.86, ketol-acid reductoisomerase (NADP+) and EC 1.1.1.383, ketol-acid reductoisomerase [NAD(P)+]].
ORGANISM
COMMENTARY hide
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
cf. EC 1.1.1.86
UniProt
Manually annotated by BRENDA team
cf. EC 1.1.1.86
UniProt
Manually annotated by BRENDA team
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SwissProt
Manually annotated by BRENDA team
SUBSTRATE
PRODUCT                       
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
(2S)-2-hydroxy-2-methyl-3-oxobutanoate + NADH + H+
(2R)-2,3-dihydroxy-3-methylbutanoate + NAD+
show the reaction diagram
COFACTOR
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
KM VALUE [mM]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
0.005 - 1.1
NADH
additional information
NADH
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Km-value for NADH is below 0.001 mM, pH 7, temperature not specified in the publication, cosubstrate: (2S)-2-hydroxy-2-methyl-3-oxobutanoate
TURNOVER NUMBER [1/s]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
0.1 - 0.46
NADH
kcat/KM VALUE [1/mMs-1]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
8 - 200
NADH
8
additional information
NADH
Thermacetogenium phaeum
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kcat/Km for NADH is at least 460 /mM*s, pH 7, temperature not specified in the publication, cosubstrate: (2S)-2-hydroxy-2-methyl-3-oxobutanoate
8
pH OPTIMUM
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
Crystallization/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
in complex with substrate analog L-tartaric acid, to 2.5 A resolution. The enzyme displays a six-member specificity loop, with residues Arg48 and Ser52 forming hydrogen bonds to the NAD(H) phosphate
apo-enzyme, to 1.39 A resolution, and in complex with NADP+. Enzyme accepts both cofactors NADH and NADPH. Insertions near the N-terminus of the specificity loop probably determine cofactor specificity, the laboratory engineering of NADH preference involved specific loop substitution
in complex with NADH, to 1.54 A resolution. The specificity loop differs significantly from any other crystallized ketol-acid reductoisomerases. Glu46, the first residue of the beta2alphaB-loop, lies along the N3 edge of the adenine moiety and forms a bi-dentate interaction with the O2' hydroxy of the ribose. The position of this glutamate is stabilized by a hydrogen bond interaction with Asn55
to 1.54 A resolution. Structure contains 2 Mg2+ ions and NADH. Glu46, the first residue of the beta2alphaB-loop, lies along the N3 edge of the adenine moiety and forms a bi-dentate interaction with the O2 hydroxy of the ribose. The position of this glutamate is stabilized by a hydrogen bond interaction with Asn55
Cloned/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
expression in Escherichia coli