Enhancement of stability of immobilized glucose oxidase by modification of free thiols generated by reducing disulfide bonds and using additives

Stability of glucose oxidase (GOD) immobilized with lysozyme has been considerably enhanced by modification of free thiols generated by reducing disulfide bonds using β-mercaptoethanol and N-ethylmaleimide in conjunction with additives like antibiotics and salts. Thermal stability of immobilized GOD was quantified by means of the transition temperature, T m and the operational stability by half-life t 1/2 at 70 °C. Modification of the free thiols in the enzyme coupled with the presence of kanamycin, NaCl, and K 2SO 4, led to increase in T m, to 80, 82 and 84 °C (compared to 75 °C in control) and t 1/2 by 7.7-, 11- and 22-fold, respectively, indicating that this method can be effectively used for enhancing the stability of enzymes.