A rubredoxin and a flavodoxin have been purified and characterized from soluble extracts of a sulfate-reducing bacterium able to grow with N2 as the only nitrogen source: Desulfovibrio desulfuricans strain Berre-Eau. These two electron carriers have characteristics similar to homologous proteins found in other Desulfovibrio species (molecular mass, absorption spectrum, extinction coefficient and amino acid composition). In contrast to rubredoxin, flavodoxin mediates electron transfer in the reduction of sulfite to sulfide and in hydrogen evolution from pyruvate, when in the presence of hydrogenase
