Fig. 4
X-band continuous-wave EPR measurements of AOX-SMPs during NADH:O2 turnover in the presence of respiratory chain inhibitors. 16 K (left) and 40 K (right) EPR spectra of AOX-SMPs (25 mg/mL SMP protein and 0.01 mg AOX mg− 1) reduced by 20 mM NADH in presence of the inhibitors marked and supplemented by additional O2 flow where stated. Sample A was prepared aerobically, without additional O2. The main respiratory chain enzymes that contribute to the SQ signal at g ~ 2 in each sample are indicated on the right-hand panel. Inhibitor concentrations: 100 μM carboxin (complex II Q-site inhibitor), 100 μM antimycin A (complex III Qi site inhibitor),100 μM piericidin A (complex I Q-site inhibitor). EPR measurement conditions: 2.02 mW microwave power