Stoicheometries and rates of proton translocation associated with respiratory reduction of NO3- have been measured for spheroplasts of Escherichia coli grown anaerobically in the presence of NO3-. Observed stoicheiometries [leads to H+/NO3- ratio; P. Mitchell (1966) Chemiosmotic Coupling in Oxidative and Photosynthetic Phosphorylation, Glynn Research, Bodmin] were approx. 4 for L-malate oxidati...

Initial velocity studies of immunopurified spinach nitrate reductase have been performed under conditions of controlled ionic strength and pH and in the absence of chloride ions. Increased ionic strength stimulated NADH:ferricyanide reductase and reduced flavin:nitrate reductase activities and inhibited NADH:nitrate reductase, NADH:cytochrome c reductase and reduced methyl viologen:nitrate redu...

Nitrate reductase (NR) activity and nitrite reductase (NiR) mRNA levels were monitored in Black Mexican Sweet maize (Zea mays L.) suspension cultures after the addition of nitrate. Maximal induction occurred with 20 millimolar nitrate and within 2 hours. Both NR and NiR mRNA were transiently induced with levels decreasing after the 2 hours despite the continued presence of nitrate in the medium...

This research investigated spatial-temporal variation in benthic bacterial community structure, rates of denitrification and dissimilatory nitrate reduction to ammonium (DNRA) processes and abundances of corresponding genes and transcripts at three sites-the estuary-head, mid-estuary and the estuary mouth (EM) along the nitrate gradient of the Colne estuary over an annual cycle. Denitrification...

The contents of the lower alimentary tract from rats fed a semisynthetic, pectin-supplemented diet showed increased nitrate reductase activity and an increase in the amount of luminal contents in the intestine and cecum. Nitrate reductase activity was associated with the insoluble fraction of the gut contents which was sedimented by centrifugation (5,100 X g,20 min) and was abolished after trea...

Nucleotide sequences were determined for cDNA clones for squash NADH:nitrate oxidoreductase (EC 1.6.6.1), which is one of the most completely characterized forms of this higher plant enzyme. An open reading frame of 2754 nucleotides began at the first ATG. The deduced amino acid sequence contains 918 residues, with a predicted Mr = 103,376. The amino acid sequence is very similar to sequences d...

Root nodule senescence induced by nitrate and ammonium in Pisum sativum L. was defined by determining nitrogenase activity and leghemoglobin content with the acetylene reduction and pyridine hemochrome assays. Root systems supplied with 100 mm KNO(3) or 100 mm NH(4)Cl exhibited a decrease in nitrogenase activity followed by a decline in leghemoglobin content. Increasing the CO(2) concentration ...

Vibrio cholerae lives in different habitats, varying from aquatic ecosystems to the human intestinal tract. The organism has acquired a set of electron transport pathways for aerobic and anaerobic respiration that enable adaptation to the various environmental conditions. We have inactivated the V. cholerae ccmE gene, which is required for cytochrome c biogenesis. The resulting strain is defici...

1. In rice seedlings synthesis of methyl viologen-nitrite reductase was stimulated by light, as was that of NADH-nitrate oxidoreductase (EC 1.6.6.1). A small residual effect of light on the synthesis of the enzymes persisted in the dark for a short time. 2. In etiolated seedlings exposed to light and nitrate, a lag period of 3 h was necessary before enzyme synthesis commenced, whereas in green ...

Chlorate-resistant mutants corresponding to each known genetic locus (chlA, chlB, chlC, chlD, chlE) were isolated from Escherichia coli K-12. All these mutants showed decreased amounts of membrane-bound nitrate reductase, cytochrome b, and formic dehydrogenase, but all had normal succinic dehydrogenase activity. Proteins from the cytoplasmic membranes of these mutants were compared to those of ...