Description
In enzymology, a leucine dehydrogenase (EC 1.4.1.9) is an enzyme that catalyzes the chemical reaction: L-leucine + H2O + NAD+ ↔ 4-methyl-2-oxopentanoate + NH3 + NADH + H+. The 3 substrates of this enzyme are L-leucine, H2O, and NAD+, whereas its 4 products are 4-methyl-2-oxopentanoate, NH3, NADH, and H+. This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-NH2 group of donors with NAD+ or NADP+ as acceptor. This enzyme participates in valine, leucine and isoleucine degradation and valine, leucine and isoleucine biosynthesis.
Abbr
Leucine dehydrogenase (Bacillus sp.)
Applications
This enzyme is useful for enzyme determination of L-leucine and the activity of leucine amino-peptidase.
Appearance
White amorphous powder, lyophilized
Enzyme Commission Number
EC 1.4.1.9
Activity
GradeⅡ 20U/mg-solid or more (containing approx. 70% of stabilizers)
Contaminants
Leucylpeptide decomposing enzymes (Leu-Val) < 1.0×10⁻²% (Leu-Gly-Gly) < 1.0×10⁻²% NADH oxidase < 1.0×10⁻²%
pH Stability
pH 5.5-10.5 (25°C, 20hr)
Michaelis Constant
1.0×10⁻³M (L-Leucine), 3.9×10⁻⁴M (NAD⁺), 3.5×10⁻⁵M (NADH), 3.1×10⁻⁴M [α-Ketoisocaproate (α-KIC)], 2.0×10⁻¹M (NH₃)
Structure
6 subunits per mol of enzyme
Optimum pH
10.5-10.8 (L-Leu→α-KIC), 9.4 (α-KIC→L-Leu)
Optimum temperature
above 70°C
Thermal stability
below 60°C (pH 6.9, 10min)
Stability
Stable at-20°C for at least one year
Stabilizers
2-Mercaptoethanol, L-cysteine, dithiothreitol, ethylenediaminetetraacetate
Inhibitors
Na₂S, Hg⁺⁺, Cu⁺⁺, Co⁺⁺, Mg⁺⁺, p-chloromercuribenzoate
Synonyms
EC 1.4.1.9; Leucine dehydrogenase; L-leucine: NAD+ oxidoreductase (deaminating); L-leucine dehydrogenase; L-leucine: NAD+ oxidoreductase (deaminating); LeuDH
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