CYCLIC VOLTAMMETRY OF 2 FE-FERREDOXINS FROM HALOBACTERIUM OF THE DEAD SEA

The charge transferred during the reduction of halobacterial ferredoxin on a dropping mercury electrode has been measured by cyclic voltametry. In fresh native ferredoxin, one electron was transferred at -0.62 V relative to 0.1 M Ag/AgCl electrode. The potential varies by about 30 mV per pH unit. Up to 3.5 electrons were transferred around this potential per ferredoxin molecule, after long storing or denaturation by exposure to low pH. The charge transferred together with the pH dependence of the reduction potential indicated reduction of the preoxidized crysteine on the mercury surface. The method allows analytical determination of ferredoxin at concentrations as low as 5×10-7 mol l-1. © 1979 Elsevier Sequoia S.A.