Description
Glucose-6-phosphate dehydrogenase (G6PD or G6PDH) (EC 1.1.1.49) is a cytosolic enzyme that catalyzes the chemical reaction:D-glucose 6-phosphate + NADP+ ↔ 6-phospho-D-glucono-1,5-lactone + NADPH + H+. This enzyme is in the pentose phosphate pathway, a metabolic pathway that supplies reducing energy to cells (such as erythrocytes) by maintaining the level of the co-enzyme nicotinamide adenine dinucleotide phosphate (NADPH).
Abbr
Chemically modified G6PDH, Recombinant (Leuconostoc mesenteroides)
Species
Leuconostoc mesenteroides
Applications
Use Glucose-6-phosphate Dehydrogenase for the determination of blood glucose or creatine kinase.
Appearance
White lyophilizate
Activity
>30 U/mg lyophilizate
Contaminants
ATPase: <0.02 Creatine kinase: <0.001 Glutamate dehydrogenase: <0.01 Glutathione reductase: <0.001 Hexokinase and GIucose dehydrogenase: <0.05 Myokinase: <0.05 ''NADH oxidase'': <0.02 ''NADPH oxidase'': <0.0005 6-Phosphogluconate dehydrogenase: <0.001 Phophoglucose isomerase : <0.01 Phosphoglucomutase: <0.001 Glucose: <0.3 μg/mg lyophilizate
Molecular Weight
110 kD (2 identical subunits 55,000 D)
Michaelis Constant
NAD: 1.4 x 10-4 mmol/l NADP: 3.7 x 10-5 mmol/l Glucose-6-P: 3.7 x 10-4 mmol/l (NAD as coenzyme) Glucose-6-P: 2.0 x 10-4 mmol/l (NAD as coenzyme)
Specificity
G6P-DH is highly specific for glucose-6-phosphate and does not react with fructose-6-P, fructose-1,6-P2 or glucose-1P. 2-Deoxyglucose-6-P is slowly oxidized with NAD (5%) and with NADP (4%).
Activators
Phosphate, 5 mmol/l: 100% (NAD), 80% (NADP) Phosphate, 50 mmol/l: 100% (NAD), 80% (NADP) Without Mg2+: 90% (NAD), 80% (NADP) Mg2+, 3 mmol/l: 100% (NAD), 100% (NADP) Mg2+, 30 mmol/l: 100% (NAD), 100% (NADP) HCO3-, 3 mmol/l: 100% (NAD), 100% (NADP)
Thermal stability
Up to +40°C for native G6P-DH, up to +50°C for modified G6P-DH
Stability
At +2 to +8°C within specification range for 18 months. Store dry.
Inhibitors
NADPH is a competitive inhibitor in the NAD-dependent reaction. Unlike the yeast enzyme, myristic acid, dehydroepiandrosterone and palmitoyl CoA do not inhibit.
Synonyms
D-glucose 6-phosphate dehydrogenase; glucose 6-phosphate dehydrogenase (NADP); NADP-dependent glucose 6-phosphate dehydrogenase; 6-phosphoglucose dehydrogenase; Entner-Doudoroff enzyme; glucose-6-phosphate 1-dehydrogenase; G6PDH; GPD; glucose-6-phosphate dehydrogenase