Electrochemistry of drug action I: electrooreduction of ferredoxins.

Ferredoxin serves as an electron carrier in the oxidation-reduction system in anaerobic microorganisms, transferring electrons from a low potential donor to electron-accepting biochemicals. The anaerobicidal activity of some drugs may be due to their interference with the electron transport function of ferredoxin. Two types of ferredoxins (isolated from Clostridium pasteurianum and spinach) were studied, and their electrochemical reduction and biochemical properties were analyzed using a sensitive ac polarographic technique. The reduction potential of both ferredoxins was linearly related to pH. The mechanisms of electron transport in ferredoxin molecules were found to be related to their sulfur-iron bonds. The dissociation of the sulfur-iron bonds resulted in the formation of a free sulfhydryl group and the interruption of the electroactivity of ferredoxin. This sulfur-iron dissociation process was found to be pH dependent. The electroreduction of ferredoxins was an energy-requiring, pH-dependent process.