How can I calculate hydrogen peroxide production (g/L) and glucose consumption (mg/dL) by glucose oxidase reaction. Where can I get this information? For example, if I have 100mg/dL, then how much H2O2 will generate with respective time and temperature? Thank you in advance
Dear Colleague,
Glucose concentration can be easily determined spectrophotometricaly with a kit sold by Sigma (Glucose assay kit) which costs 60 euros for 20 determinations.This kit is for the quantitative, enzymatic determination of glucose in food and other material. Glucose is phosphorylated by adenosine triphosphate (ATP) in the reaction catalyzed by hexokinase. Glucose-6-phosphate (G6P) is then oxidized to 6-phospho-gluconate in the presence of oxidized nicotinamide adenine dinucleotide (NAD) in a reaction catalyzed by glucose-6-phosphate dehydrogenase (G6PDH). During this oxidation, an equimolar amount of NAD is reduced to NADH. The consequent increase in absorbance at 340 nm is directly proportional to glucose concentration.
Glucose concentration, alternatively, is monitored in our microroganism culture conditions by using a glucose-determination special electrode set on a monitoring device similar to a pH-meter. The special electrode is not cheap but it works quite well (for repeated numerous determinations).
Peorxide production can be also followed by a special electrode (peroxide-specific). But, most time, people in my lab are using a phenol/4-aminoantipyrene solution which yields an adduxt upon reacting with peroxides that specifically abosrb light at 510 nm.
Both glucose and peroxides can thus be spectrophotometrically determines.
Good luck with your experiments,
Prof P. Urban
For the enzyme GOase, each mole of glucose is oxidized to a mole of H202. Calculate the molar concentration of glucose you have and using the Km and Vmax (kinetic constants) for the specific GOase (e.g. fungal) used you can get an idea of the amount of H202 produced at the temperature the constants were recorded. For rough approximation, assume the reaction rate doubles for each 10 C increase in temp.
Hi again,
Yes, Wayne made a good point.
Just to give you an idea of what you can expect. You have a glucose solution at 100 mg/dL , as you mention. Given the molecular weight of glucose at 180 g/mole, that is a 5.55 mM glucose solution. If all the glucose is transformed in glucunolactone in your experiment (that is, you do not look at kinetics but you just let the reaction goes to completion), you will get 5.55 mM in H2O2 at the end. That is a solution at 0.19 g/L (if I'm corect) since the molecular weight of hydrogen peroxide is 34 g/mole.
Best regards
Phil Urban
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