NOX hyperactivation induced by thermal incubation. (A) NOX was incubated at different temperatures (37, 70 and 80°C) for 1 h and then measured at 65°C, in 50 mM sodium phosphate at pH 7 under either limited (white bars) or saturated (black bars) flavin cofactor conditions (150 μM). The relative activity was calculated for each condition (limited or saturated flavin cofactor), taking as fraction 1 the initial activity observed without thermal incubation. (B) Arrhenius' plot of the reaction catalyzed by soluble NOX which was thermal incubated at 80°C for 45 minutes (squares) and by soluble NOX which did not undergo to thermal incubation (rhombus). The negative linear regressions were calculated for each sample, resulting the following equations: for thermally incubated NOX (y = -4339,9 × + 16,52. R2 = 0,987) and for non thermally incubated NOX (y = -5828,8 × + 20,571. R2 = 0,995).