L-Glutamic Dehydrogenase (NADP) from Proteus sp.

Isoelectric point : 4.6
Michaelis constants : 1.1 X 10^-3M (NH₃), 3.4 X 10^-4M (α-Ketoglutarate)
1.2 X 10^-3M (L-Glutamate), 1.4 X 10^-5M (NADPH), 1.5 X 10^-5M (NADP⁺)
Structure : 6 subunits (M.W.50,000) per mol of enzyme
Inhibitors : Hg⁺⁺, Cd⁺⁺, p-chloromercuribenzoate, pyridine, 4-4′-dithiopyridine,
2,2′-dithiopyridine
Optimum pH : 8.5 (α-KG→L-Glu) 9.8 (L-Glu→α-KG)
Optimum temperature : 45^oC(α-KG−L-Glu) 45-55^oC (L-Glu→α-KG)
pH stability : pH 6.0 - 8.5 (25^oC, 20hr)
Thermal stability : below 50^oC (pH 7.4, 10min)

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 (URH-201) in clinical analysis. In vitro, various activity assays of this enzyme examine the conversion of α-ketoglutarate to L-glutamate, in the presence of excess ammonium ions (NH₄⁺) and NADPH.

L-glutamic dehydrogenase catalyzes the conversion of glutamate to α-ketoglutarate.

Solution in 50 mM Tris HCl, pH 7.8, 5 mM Na₂EDTA containing 0.05% sodium azide

Note: Do not confuse with non-specific L-GLDH, EC 1.4.1.3.

One unit will reduce 1.0 μmole of α-ketoglutarate to L-glutamate per min at pH 8.3 at 30 °C in the presence of ammonium ions and NADPH.