Oxidation-reduction properties of the two Fe4S4 clusters in Clostridium pasteurianum ferredoxin

The ferredoxin from Clostridium pasteurianum contains two Fe4S4 clusters. In this paper we determine their oxidation-reduction midpoint potentials; we find them to be essentially identical (within 10 mV) and to have pH-independent Em values of -412 +/- 11 mV from pH 6.3 to 10.0.