Reduction of ferredoxin:thioredoxin reductase by artificial electron donors.

The ferredoxin:thioredoxin reductase is an essential enzyme of the light dependent regulatory system in oxygenic photosynthesis. It is composed of two dissimilar subunits and contains a 4Fe-4S cluster and a redox-active disulfide bridge. Artificial electron donors of redox potentials below -300 mV are capable of reducing the disulfide bridge. Based on our results we speculate that a group of more negative potential than the disulfide bridge is the first acceptor of the electrons in FTR. The chemical reduction of FTR has been used successfully for the detection of the enzyme during its purification.