Characterization of the electron transport system in Brucella abortus

The electron transport system in Brucella abortus has been characterized. Spectral studies of membrane preparations have indicated the presence of cytochromes a + a3 (maxima at 612 nm), cytochrome b (maxima at 560, 530, and 428 nm), cytochrome c (maxima at 552 and 522 nm), cytochrome o (maxima of carbon monoxide complex at 418 nm), and flavoproteins (minimum at 582 and 450 nm). Cytochromes a + a3 appeared only after cells had reached late log phase, possibly due to lowered oxygen tension in the medium. Dehydrogenases were shown to be present for D-erythritol 1-phosphate, L-lactate, reduced nicotinamide adenine dinucleotide, and succinate. All of the above substrates reduced the electron transport chain and at least some of the flavoproteins, indicating similar pathways of electron transport. N-ethylmaleimide, p-chloromercuribenzoate, and KCN were the only electron transport inhibitors that blocked electron transport by 100%. The system seemed to be uniquely resistant to other electron transport inhibitors.