Literature summary for 1.1.1.85 extracted from

Yamada, T.; Akutsu, N.; Miyazaki, K.; Kakinuma, K.; Yoshida, M.; Oshima, T.
Purification, catalytic properties, and thermal stability of threo-Ds-3-isopropylmalate dehydrogenase coded by leuB gene from an extreme thermophile, Thermus thermophilus strain HB8 (1990), J. Biochem., 108, 449-456.

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Crystallization (Commentary)

Crystallization (Comment)	Organism
recombinant enzyme expressed in Escherichia coli, ammonium sulfate precipitation	Thermus thermophilus

General Stability

General Stability	Organism
complete loss of activity in presence of 4 M urea	Thermus thermophilus

Inhibitors

Inhibitors	Comment	Organism	Structure
1,2-Cyclohexanediamine-N,N,N',N'-tetraacetate	-	Thermus thermophilus

KM Value [mM]

KM Value [mM]	KM Value Maximum [mM]	Substrate	Comment	Organism	Structure
0.08	-	threo-Ds-3-Isopropylmalate	60°C	Thermus thermophilus
0.63	-	NAD+	60°C	Thermus thermophilus

Metals/Ions

Metals/Ions	Comment	Organism	Structure
K+	in 1.1 M potassium phosphate buffer, pH 7.6, the activity is over 20times that in 0.1 M sodium phosphate. Optimal KCl concentration is above 2 M, enhances activity 20times	Thermus thermophilus
Mg2+	divalent cation required, most active in presence of 0.1 mM Mn2+ or 1 mM Mg2+	Thermus thermophilus
Mn2+	divalent cation required, most active in presence of 0.1 mM Mn2+ or 1 mM Mg2+	Thermus thermophilus
NH4+	NH4Cl, optimal concentration is about 0.4 M, enhances activity 18times	Thermus thermophilus
Rb+	RbCl enhances activity	Thermus thermophilus

Organism

Organism	UniProt	Comment	Textmining
Thermus thermophilus	-	-	-

Purification (Commentary)

Purification (Comment)	Organism
gene cloned in Escherichia coli	Thermus thermophilus

Renatured (Commentary)

Renatured (Comment)	Organism
enzyme solution containing 3.2 M urea is diluted 10times with a urea-free buffer. In samples containing 0.2 mM MnCl2 the activity is restored to 55-60%, full activity is recovered in absence of MnCl2	Thermus thermophilus

Storage Stability

Storage Stability	Organism
-20°C, stable for at least 6 months when frozen quickly, 40% inactivation when frozen slowly	Thermus thermophilus
4°C , 50 mM potassium phosphate buffer pH 7.6, 0.5 mM EDTA, 6 months, stable	Thermus thermophilus

Substrates and Products (Substrate)

Substrates	Comment Substrates	Organism	Products	Comment (Products)	Rev.	Reac.
(2R,3S)-3-isopropylmalate + NAD+	-	Thermus thermophilus	2-oxoisocaproate + NADH + H+ + CO2	-	?

Subunits

Subunits	Comment	Organism
dimer	2 * 35000-40000, SDS-PAGE	Thermus thermophilus

Temperature Stability [°C]

Temperature Stability Minimum [°C]	Temperature Stability Maximum [°C]	Comment	Organism
additional information	-	high concentrations of KCl considerably protect the enzyme from irreversible thermal denaturation	Thermus thermophilus
87	-	denaturation temperature is higher than 87°C	Thermus thermophilus

pH Optimum

pH Optimum Minimum	pH Optimum Maximum	Comment	Organism
7.2	-	at 75°C, in presence of K+	Thermus thermophilus
9	-	75°C, without K+	Thermus thermophilus

Cofactor

Cofactor	Comment	Organism	Structure
NAD+	-	Thermus thermophilus

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Release 2026.1 (March 2026)