1.9.6.1	2 ferrocytochrome + 2 H+ + nitrate	-	
1.9.6.1	additional information	an insertion in the napA gene leads to a complete loss of enzyme activity but does not abolish the ability of Alcaligenes eutrophus to use nitrate as a nitrogen source or as an electron acceptor in anaerobic respiration. Nevertheless, the NAP-deficient mutant shows delayed growth after transition from aerobic to anaerobic respiration, suggesting a role for periplasmic nitrate reductase in the adaptation to anaerobic metabolism	
1.9.6.1	additional information	NapABC enzyme is responsible for nitrate dissimilation. Periplasmic nitrate reductase (NapABC enzyme) can function in anaerobic respiration but does not constitute a site for generating proton motive force. napF-lacZ is expressed preferentially at relatively low nitrate concentrations in continuous cultures. This finding support the hypothesis that NapABC enzyme may function in Escherichia coli when low nitrate concentrations limit the bioenergetic efficiency of nitrate respiration via NarGHI enzyme	
1.9.6.1	additional information	the nap operon encodes the only nitrate reductase in Campylobacter jejuni and that it is essential in mediating growth using nitrate as a terminal electron acceptor under oxygen-limited conditions	
1.9.6.1	nitrate + ferrocytochrome	-	
1.9.6.1	nitrate + ferrocytochrome	NapG and H, but not NapF, are essential for electron transfer from ubiquinol to NapAB. NapC is essential for electron transfer from both ubiquinol and menaquinol to NapAB. It is proposed that NapG and H form an energy conserving quinol dehydrogenase functioning as either components of a proton pump or in a Q cycle, as electrons are transferred from ubiquinol to the membrane-bound cytochrome NapC	
1.9.6.1	nitrate + ferrocytochrome	periplasmic nitrate reductase is expressed under nitrate-limiting conditions. NapG and NapH form a quinol dehydrogenase that couples electron transfer from the high midpoint redox potential ubiquinone-ubiquinol couple via cytochrome NapC and NapB to NapA	
1.9.6.1	nitrate + ferrocytochrome	the periplasmic cytochrome c-linked nitrate reductase is encoded by the napFDAGHBC operon. The napF operon apparently encodes a low-substrate-induced reductase that is maximally expressed only at low levels of nitrate. Expression is suppressed under high-nitrate conditions. In contrast, the narGHJI operon is only weakly expressed at low nitrate levels but is maximally expressed when nitrate is elevated. The narGHJI operon is therefore a high-substrate-induced operon that somehow provides a second and distinct role in nitrate metabolism by the cell. Nitrite, the end product of each enzyme, has only a minor effect on the expression of either operon. Finally, nitrate, but not nitrite, is essential for repression of napF gene expression. These studies reveal that nitrate rather than nitrite is the primary signal that controls the expression of these two nitrate reductase operons in a differential and complementary fashion	
1.9.6.1	nitrate + reduced acceptor	the enzymes EC 1.7.99.4 and EC 1.9.6.1 are probably identical, in vivo cytochrome serves as electron donor in the electron transport chain to nitrate	
1.9.6.1	nitrate + reduced acceptor	electron transport chain in vivo: Fe3 + via specific cytochrome-nitrate reductase to NO3-