Table IV. Kinetic constants of GOX1 and GOX3 for molecular oxygen

Kinetic constants were determined using the standard reaction mix for measurements using the oxygen electrode, varying the substrate concentration from 5 to 10 mm and monitoring the decreasing oxygen concentration; 4 to 10 µg of purified enzyme was used. S0.5 and Vmax values were determined using the nonlinear regression fit to the sigmoidal Hill equation f(x) = axb/cb + xb (Sigma Plot software). Shown are mean values ± se of three independent experiments.

SampleS0.5kcatkcat/KmHill Coefficient
µmmin−1min−1 mm−1
GOX1
 Glycolate187 ± 18831 ± 674,4461.72 ± 0.08
GOX3
 Glycolate202 ± 14538 ± 352,6561.94 ± 0.07
l-Lactate153 ± 6851 ± 295,5541.93 ± 0.06