Does dexamethasone inhibit glucose oxidase: an analysis in kinetics and molecular study.

Objectives: Glucose oxidase is an enzyme that is widely used in biosensors, especially kits for measuring blood sugar. Many diabetics use this type of kit to determine their blood sugar level. Aspergillus niger is the most important source of glucose oxidase for use in biosensors. Diabetes causes secondary diseases in patients for which medications are prescribed to improve them. Dexamethasone, a corticosteroid, is one of the drugs prescribed to diabetics to cure some secondary diseases. In this study, the effect of this drug on glucose oxidase was investigated from a kinetic and molecular point of view.

Methods: In this study, the kinetics of drug binding to the enzyme was measured and the type of inhibition was determined by Lineweaver-Burk plot. The Ki value of the drug was determined by drawing the secondary curve. Using fluorescence spectrophotometry and molecular docking, the binding of the drug to the enzyme was confirmed.

Results: The results showed that the drug inhibits the enzyme non-competitively. Determining the kinetics parameters of the drug-enzyme interaction showed that the drug acts as a potent inhibitor. Study at the molecular level by fluorescence spectrophotometer showed that the drug attachment alters the enzyme conformation to more compaction. In silico results showed that the drug is placed between two helices that are outside the active site and binds to the enzyme by three hydrogen bonds.

Conclusions: The result of this study is useful because it suggests that in diabetic patients taking dexamethasone, the amount of glucose declared by the kit may not be real due to the inhibition of glucose oxidase.