The effect of oxygen upon the inactivation rate of glucose oxidase was studied. Tests on enzyme stability during catalytic turnover were conducted under a range of oxygen partial pressures. A standard activity assay was used to monitor changes in glucose oxidase activity. Studies revealed that oxygen influenced the inactivation of glucose oxidase. Inactivation rates during catalytic turnover ranged between 0.01143 +/- 0.0016 h-1 under 10 kPa oxygen to 0.04879 + / - 0.0023 h-1 under 101 kPa oxygen. Statistically different inactivation rates were obtained at oxygen partial pressures of 10, 15, 21, 51, and 76 kPa. The enzymatic turnover number decreased from 11.0 x 10(4) to 5.7 x 10(4) when the oxygen partial pressure increased from 10 to 101 kPa, suggesting that enzyme utilization was most efficient at low oxygen partial pressures (< 15 kPa).