Fig. 6
Comparison of SQ EPR signals in antimycin A- and carboxin-inhibited SMPs and AOX-SMPs. X-band EPR spectra of SMPs (red) and AOX-SMPs (black, 0.01 mg AOX mg− 1) frozen immediately or following a 2-min incubation with 40 mM NADH under high O2 flow. Samples were treated with 100 μM carboxin and 100 μM antimycin A. Pre-activated samples were mixed with 1 mM NADH and incubated at room temperature for 5 min in an aerobic atmosphere prior to EPR sample preparation. The anaerobic AOX-SMP sample was incubated in a Braun UniLab-plus glovebox (O2 < 0.5 ppm, N2 atmosphere) at room temperature (22 °C) for 1 h prior to addition of 20 mM NADH. The sample was frozen within 30 s of substrate mixing. EPR measurement conditions: 2.02 mW microwave power, 40 K