Study of the effect of some organic solvents on the activity and stability of glucose oxidase

The relative activity and thermal stability of native and covalently immobilized glucose oxidase (GOD) onto polyamide-6 (PA-6) membrane was studied at temperatures of 28, 45 and 60 °C for 10 h and in the presence of organic solvents (methylol, ethyleneglycol, glycerol) with concentrations 10%, 30% and 60%. It was proven that immobilized GOD had better stability than the native one in all the three organic solvents. At 28 °C, the strongest activating and stabilizing effect on the free GOD was observed with 10% methylol and on the immobilized GOD with 10% and 30% methylol. The addition of certain concentrations of ethyleneglycol and glycerol to the enzyme at higher temperatures was found to stabilize the enzyme molecule. At temperatures of 45 and 60 °C, the strongest stabilizing effect on both forms of the enzyme was exerted by glycerol (optimal stabilizing concentration of 10%). It was concluded that the most stable form of the enzyme was GOD covalently immobilized onto PA-6 membrane in the presence of 10% solution of glycerol.