Electrochemical titrations of a ferredoxin-ferredoxin:NADP+ oxidoreductase complex

Potentiometric titrations employing an electrochemical thin-layer cell indicate that complex formation between ferredoxin and ferredoxin:NADP+ oxidoreductase alters the midpoint oxidation-reduction potentials of both proteins. The midpoint potential of ferredoxin the complex becomes 22 +/- 6 mV more negative compared to ferredoxin alone while the midpoint potential of ferredoxin:NADP+ oxidoreductase becomes 23 +/- 4 mV more positive on complex formation.