Glucose oxidase

The glucose oxidase enzyme (GOx) (EC 1.1.3.4) binds to beta-D-glucose (an isomer of the six-carbon sugar glucose) and aids in breaking the sugar down into its metabolites. GOx is a dimeric protein that catalyzes the oxidation of beta-D-glucose into D-glucono-1,5-lactone, which then hydrolyzes to gluconic acid.

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The CAS number for this type of the enzyme is [9001-37-0].

In order to work as a catalyst, GOx requires a cofactor, flavin adenine dinucleotide (FAD). FAD is a common component in biological oxidation-reduction (redox reactions). Redox reactions involve a gain or loss of electrons from a molecule. In the GOx-catalyzed redox reaction, FAD works as the initial electron acceptor and is reduced to FADH₂. Then FADH₂ is oxidized by the final electron acceptor, molecular oxygen (O₂), which can do so because it has a higher reduction potential. O₂ is then reduced to hydrogen peroxide (H₂O₂).

The glucose oxidase enzyme is commonly used in biosensors to detect levels of glucose by keeping track of the number of electrons passed through the enzyme by connecting it to an electrode and measuring the resulting charge. When produced commercially for this application, it is often extracted from Aspergillus niger. This has a possible application in the world of nanotechnology when used in conjunction with tiny electrodes as glucose sensors for diabetics.

Glucose oxidase is found in honey and acts as a natural preservative. GOx at the surface of the honey reduces atmospheric O₂ to hydrogen peroxide (H₂O₂), which acts as an antimicrobial barrier.

See also

• Oxidoreductase
• Glucose meter