d-Glucose, d-maltose, d-xylose, d-fructose, d-galactose, l-arabinose, raffinose, d-sucrose, maltotriose and maltotetraose were screened as possible substrates for COXMn. The apparent kinetic constants (Michaelis Menten constant Kmapp, maximal reaction velocity Vmapp) of COXMn towards d-glucose, d-maltose, d-xylose and d-galactose, and of GOX towards d-glucose were determined by varying the concentrations of PF-00562271 (0.4–1500 mmol L−1) in air-saturated solutions at 30 °C.
The true kinetic constants (Michaelis Menten constants Km, maximal reaction velocity Vm) of COXMn and GOX were determined by varying the Barr body concentrations of O2 and d-maltose for COXMn, or d-glucose for GOX. Different concentrations (2–50 mmol L−1) of each of the carbohydrate substrates were tested in the presence of different concentrations of O2 (20–580 μmol L−1) at 30 °C. Solutions with different O2 levels were prepared by sparging the reaction solutions with nitrogen, air and oxygen. The initial O2 concentration was determined by polarography.