GLUCOSE TESTING
An improved glucose oxidase enhances glucose detection in test strips
Glucose oxidase is a component of solid phase enzymes used in the glucose testing market. There is a need for better enzymes to make more reliable, accurate and reproducible tests. ZA Biotech/CSIR have shown that they can couple glucose oxidase to Spherezymes and retain activity. Glucose oxidase is coupled to Horse Radish Peroxidase and it is important to demonstrate that both enzymes can be coupled to Spherezymes.
Glucose oxidase (EC 1.1.3.4) binds to beta-D-glucopyranose (a hemiacetal form of the six-carbon sugar glucose) and aids in breaking the sugar down into its metabolites. Glucose oxidase is a dimeric protein that catalyzes the oxidation of beta-D-glucose into D-glucono-1,5-lactone, which then hydrolyzes to gluconic acid.
In order to work as a catalyst, Glucose oxidase 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 Glucose oxidase-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 detecting electrons passed through the enzyme by connecting it to an electrode and measuring the resulting charge. ZA Biotech uses Glucose oxidase extracted from Aspergillus niger together with horse radish peroxidase in its glucose sensor. The two enzymes are coupled to each other using the SphereZymes technology. Glucose is detected by the generation of a brown product by the coupled enzymes which id detected colourimetrically. In this way ZA Biotech uses its nanotechnology as glucose sensors for diabetics.
The use of the new formulation of glucose oxidase particles promises to improve the accuracy, reliability and precision of the measurements together with a reduction in blood volume.
Product information and other details can be obtained from Dr R D Gordon, email bobgordon@zabiotech.com.