Table 5.

DQ cellular redox reaction

NQO1-mediated two electron DQ reduction to DQH2

$DQ+NAD(P)H+H^{+}\to DQ{H}_2+NAD{(P)}^{+}$

Complex III-mediated DQH2 oxidation to DQ

$DQ{H}_2+2Cyt{C}_o\to DQ+\text{ 2 }Cyt{C}_r$

One electron DQ reduction to $\mathbf{\text{D}}{\mathbf{\text{Q}}}^{\text{•}-}$

$DQ+\frac{1}{2}RH\to D{Q}^{•-}+\frac{1}{2}{R}^{+}+\frac{1}{2}{H}^{+}$

$\mathbf{\text{D}}{\mathbf{\text{Q}}}^{•-}$ autooxidation, superoxide dismutation to H2O2

$2D{Q}^{•-}+O_2+2H^{+}\to H_2{O}_2+2DQ$

Peroxidase-mediated DQH2 oxidation to DQ

$DQ{H}_2+H_2{O}_2{}^{+}\to DQ+2H_{2}O$

$\mathbf{\text{D}}{\mathbf{\text{Q}}}^{•-}$ disproportionation to DQH2 and DQ

$2D{Q}^{•-}+2H^{+}\to DQ{H}_2+DQ$

RH and R⁺ are the reduced and oxidized forms of electron donor(s) for one-electron DQ reductases; $D{Q}^{•-}$ is durosemiquinone. CytC_o and CytC_r are the oxidized and reduced forms of cytochrome C, respectively.