Figure 2.

EPR spectra of NADH-reduced purified complex I from P. denitrificans. (a) Complex I (5.8 mg mL^–1) was reduced anaerobically with 15 mM NADH. EPR spectra were recorded at 100 kHz modulation frequency with a modulation amplitude of 7 G and a microwave power of 2.02 mW at the temperatures indicated. Vertical lines correspond to the g factors for the individual FeS clusters. (b) Simulation of the EPR spectrum of purified Pd-CI at 16 K. The total simulation of the combined FeS cluster signals is shown in red, with the individual simulations labelled according to the established nomenclature. FeS clusters N1b-N4 were simulated at a 1:1 ratio. Simulation parameters are given in SI Table S2.