Experimental evidence for proton motive force-dependent catalysis by the diheme-containing succinate:menaquinone oxidoreductase from the Gram-positive bacterium Bacillus licheniformis.

In Gram-positive bacteria and other prokaryotes containing succinate:menaquinone reductases, it has previously been shown that the succinate oxidase and succinate:menaquinone reductase activities are lost when the transmembrane electrochemical proton potential, Deltap, is abolished by the rupture of the bacteria or by the addition of a protonophore. It has been proposed that the endergonic reduction of menaquinone by succinate is driven by the electrochemical proton potential. Opposite sides of the cytoplasmic membrane were envisaged to be separately involved in the binding of protons upon the reduction of menaquinone and their release upon succinate oxidation, with the two reactions linked…