On the use of diethyldithiocarbamate for detection of electron-transferring copper proteins in bacterial respiratory chains



Abstract In a previous study on the anaerobic electron transport in the wild-type and a mutant strain of Paracoccus denitrificans, the differences in sensitivity towards the copper-chelating agent diethyldithiocarbamate have been interpreted to arise from a substitution of a soluble copper protein for the absent cytochrome c550. Here it is shown that two factors complicate this interpretation: (i) diethyldithiocarbamate can also inhibit through interaction with (a) site(s) located in the cytoplasmic membrane and (ii) it has the potential of being a good electron donor for c-type cytochromes. The participation of a copper protein in the denitrification pathway thus needs to be verified by independent means.