Biochemical and Clinical Applications of Glucose Oxidase (GOD)

Glucose oxidase (GOD) is a typical oxidoreductase found in honey and molds such as Penicillium notatum. It can highly specifically catalyze the β-D-glucose reaction to generate gluconic acid, which has the function of converting glucose and removing oxygen. Since GOD can quantitatively generate hydrogen peroxide, it is widely used in the field of biochemistry and clinical examination as a quantitative reagent for D-glucose. GOD can be used in biochemical research, and is clinically often used as a diagnostic enzyme, for glucose analysis, preparation of urine glucose and blood glucose test paper, and as a stabilizer for vitamin C and B12 preparations in the pharmaceutical industry. The refined enzyme can be used for clinical diagnosis, quickly and accurately determine the glucose content in body fluids, and provide reliable data for doctors to accurately determine the patient's condition. The commonly used glucose oxidase method for measuring blood sugar includes the following two products: 1. Blood glucose determination kit (glucose oxidase method)rnClinically, blood glucose determination kits (glucose oxidase method) are mainly used to quantitatively determine the content of glucose in human serum. It is small in size, easy to carry, does not require special training, and can quickly detect blood glucose results at any time. The principles of the glucose oxidase method to determine glucose in serum are as follows: (1) GOD uses oxygen and water to oxidize glucose to gluconic acid and release hydrogen peroxide. Peroxidase (POD) decomposes hydrogen peroxide into water and oxygen in the presence of chromogenic oxygen receptors, and makes the chromogenic oxygen receptor 4-aminoantipyrine and phenol dehydrocondensation into red quinone compounds, namely Trinder reaction. The amount of red quinone compounds produced is directly proportional to the glucose content. Due to the poor specificity of the Trinder reaction, some reducing substances such as uric acid, vitamin C, bilirubin and glutathione can compete with chromogenic substances for hydrogen peroxide. Thus, the hydrogen peroxide produced during the reaction is consumed, and competitive inhibition is produced, which makes the measurement result low. (2) GOD catalyzes glucose to produce hydrogen peroxide. Peroxidase catalyzes the decomposition of hydrogen peroxide in the presence of oxygen and oxidizes o-dianisidine to colored substances. The color depth is linearly related to the activity of glucose oxidase. (3) GOD catalyzes glucose to produce hydrogen peroxide, which then reacts with xylenol orange indicator under acidic conditions to produce a purple product. The absorbance at 580nm is directly proportional to the concentration of hydrogen peroxide generated, that is, directly proportional to the GOD activity. 2. Blood glucose test paper (glucose oxidase method) We often see that blood glucose test strips need to be used with a glucose oxidase blood glucose meter, which has high specificity for glucose and relatively accurate results. However, because the reaction process requires the participation of oxygen, the measurement result is easily affected by the blood oxygen content and the result is biased. The test paper is also easy to react with oxygen in the air. Generally, it should be used up within 3 to 4 months after opening, and the shelf life is relatively short.