Phosphorylation associated with nitrate and nitrite reduction in Micrococcus denitrificans and Pseudomonas denitrificans.

Abstract

Summary In cell-free extracts of Micrococcus denitrificans, phosphorylation associated with the reduction of nitrate was observed with NADH2, succinate, malate, pyruvate or glutamate as hydrogen donors. Nitrite reduction was also shown to be coupled to phosphorylation, but nitric and nitrous oxides and hydroxylamine were ineffective. Specific activities of enzymes concerned with electron transfer to nitrate (NADH2:nitrate oxidoreductase, EC 1.6.6.1), to nitrite, to cytochrome (NADH2:cytochrome c oxidoreductase, EC 1.6.2.1) and to oxygen (cytochrome c:O2 oxidoreductase, EC 1.9.3.1), which were coupled to phosphorylation were maximal in the particulate fraction collected between 70 000 to 144 000 × g. Phosphorylation linked to the reduction of nitrate or nitrite in these particles was inhibited by 2,4-dinitrophenol, arsenate, cyanide and amytal but carbon monoxide was without effect. In cell extracts of Pseudomonas denitrificans, however, phosphorylation did not occur with nitrite as the terminal acceptor.