Proton translocation coupled to carbon monoxide-insensitive and -sensitive electron transport in Pseudomonas carboxydovorans

Abstract The respiration-driven proton translocation has been measured with the oxygen pulse method and whole cells of the carbon monoxide (CO)-insensitive bacterium Pseudomonas carboxydovorans . → H⁺/O ratios of 5 to 6 were determined with endogenous substrates, pyruvate or hydrogen. In the presence of 100% CO → H⁺/O ratios were lowered to about 4. The results indicate that the Co-sensitive electron transport via the cytochromes c and a conserves more energy than the CO-insensitive electron transport via the alternative pathway with cytochrome o as terminal oxidase. The CO-sensitive a -type cytochrome was found to translocate 2 protons per oxygen atom reduced, thus accounting for the difference of the energy yield of the CO-sensitive and the CO-insensitive electron transport in P. carboxydovorans .