OXIDATION OF GLUCOSE TO GLUCONIC ACID AND REGENERATION OF NADP CATALYZED BY GLUCOSE OXIDASE AND DEHYDROGENASES

摘要

This work dealt with the determination of catalytic activity and kinetic constants of glucose oxidase ( K_M = 15.6 mM; V_(max) = 34.1×10~(-3) mg H_2O_2/min.mL), glucose 6-phosphate dehydrogenase-NADP dependent (G6PDH; K_M = 15.3 μM; V_(max) = 0.110 μM/s) and glutamate dehydrogenase-NADPH dependent (GLUDH; K_M = 0.052 μM; V_(max) = 0.192 μM/s). It was shown that, through the discontinuous process (pH 5.0, 37°C and total duration of 90 min), the interchanging of the coenzymes (NADP and NADPH) occurred. The oxidation of glucose (32 g/L) by glucose oxidase (7.000 U) through a fed-batch process (carried out for 4h at pH 5.0 and 37°C) occurred at a yield of 80%. The volume inside the reactor was varied from 100 mL up to 400 mL by adding the glucose solution according to the equation: V_(ad) = 0.15.t – 0.01875.t2 [V_(ad) = added volume up to a given time (t)].