Description
Glutamate dehydrogenase (GLDH) is an enzyme, present in most microbes and the mitochondria of eukaryotes, as are some of the other enzymes required for urea synthesis, that converts glutamate to α-ketoglutarate, and vice versa. In animals, the produced ammonia is usually used as a substrate in the urea cycle. Typically, the α-ketoglutarate to glutamate reaction does not occur in mammals, as glutamate dehydrogenase equilibrium favours the production of ammonia and α-ketoglutarate.
Abbr
GLDH (NADP) (Proteus sp.)
Applications
This enzyme is useful for enzymatic determination of NH₃, α-ketoglutaric acid and L-glutamic acid, and for assay of leucine aminopeptidase and urease. This enzyme is also used for enzymatic determination of urea when coupled with urease in clinical analysis.
Appearance
Solution with 50mM Tris-HCl buffer containing 0.05% NaN₃ and 5.0mM EDTA, pH 7.8
Enzyme Commission Number
EC 1.4.1.4
Activity
GradeⅡ∙Ⅲ 300U/mg-protein or more (9,000U/ml or more)
Contaminants
NADPH oxidase < 1.0×10⁻²% Glutathione reductase < 1.0×10⁻²% (GradeⅡ-209) < 1.0×10⁻¹% (GradeⅢ-309)
Molecular Weight
approx. 300 kDa
pH Stability
pH 6.0-8.5 (25°C, 20hr)
Michaelis Constant
1.1×10⁻³M (NH₃), 3.4×10⁻⁴M (α-Ketoglutarate), 1.2×10⁻³M (L-Glutamate), 1.4×10⁻⁵M (NADPH), 1.5×10⁻⁵M (NADP⁺)
Structure
6 subunits (M.W.50,000) per mol of enzyme
Optimum pH
8.5 (α-KG→L-Glu) 9.8 (L-Glu→α-KG)
Optimum temperature
45°C (α-KG→L-Glu) 45-55°C (L-Glu→α-KG)
Thermal stability
below 50°C (pH 7.4, 10min)
Stability
Stable at 5°C for at least 6 months
Stabilizers
Ethylenediaminetetraacetic acid (EDTA)
Inhibitors
Hg⁺⁺, Cd⁺⁺, p-chloromercuribenzoate, pyridine, 4-4'-dithiopyridine, 2,2'-dithiopyridine
Synonyms
glutamate dehydrogenase (NADP+); glutamic dehydrogenase; dehydrogenase; glutamate (nicotinamide adenine dinucleotide (phosphate)); glutamic acid dehydrogenase; L-glutamate dehydrogenase; L-glutamic acid dehydrogenase; NAD(P)-glutamate dehydrogenase; NAD(P)H-dependent glutamate dehydrogenase; glutamate dehydrogenase (NADP); EC 1.4.1.4; GLDH
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