Abstract
Minimum →H+/2e− ratios for both the NO→1/2N2O and NO→1/2N2 reactions were about 3.7 with denitrifying Paracoccus denitrificans. These ratios are only slightly less than those obtained with other N-oxides similarly linked to the oxidation of endogenous substrate. Active transport of [14C]L-proline was supported by the above two reactions of NO in denitrifying cells. NO failed to promote proline uptake with aerobically grown cells. The uncoupler, carbonyl cyanide m-chlorophenylhydrazone, abolished proline uptake and greatly diminished proton translocation with NO and other N-oxides. The results directly demonstrate for the first time that reduction of exogenous NO is energy yielding in a denitrifying bacterium.