-Five enzyme activities in midgut cytosol of Manduca sexta last instar larvae are potentially involved in the interconversion of 3fl-hydroxyecdysteroids, 3-oxoeedysteroids, and 3ct-hydroxyeedysteroids. A Sephadex G-25-filtered high-speed supernatant was used to determine some of the characteristics of the corresponding enzymes. The pH optima of eedysone oxidase and NADH-dependent 3-oxoeedystero...

Euglena gracilis contains a protein system which can utilize the reducing power of NADPH in the ribonucleotide reductase-catalyzed reduction of CTP. The proteins required for this reaction are a flavoprotien with a molecular weight of approximately 185,000 which is functionally similar to thioredoxin reductase (NADPH), EC 1.6.4.5, and another protein (Protein I) whose function in the reaction i...

The human pathogen Neisseria meningitidis is capable of growth using the denitrification of nitrite to nitrous oxide under microaerobic conditions. This process is catalyzed by two reductases: nitrite reductase (encoded by aniA) and nitric oxide (NO) reductase (encoded by norB). Here, we show that in N. meningitidis MC58 norB is regulated by nitric oxide via the product of gene NMB0437 which en...

Mycobacterium tuberculosis places an enormous burden on the welfare of humanity. Its ability to grow and its pathogenicity are linked to sulfur metabolism, which is considered a fertile area for the development of antibiotics, particularly because many of the sulfur acquisition steps in the bacterium are not found in the host. Sulfite reduction is one such mycobacterium-specific step and is the...

The nitrite anion is reduced to nitric oxide (NO*) as oxygen tension decreases. Whereas this pathway modulates hypoxic NO* signaling and mitochondrial respiration and limits myocardial infarction in mammalian species, the pathways to nitrite bioactivation remain uncertain. Studies suggest that hemoglobin and myoglobin may subserve a fundamental physiological function as hypoxia dependent nitrit...

adult liver microsomal preparations; neonatal liver microsomal preparations were also active. Kidney microsomal preparations were about 12 % as active, but microsomal suspensions from other tissues had less than 5 % of the adult liver microsomal activity (Table 1). In experiments involving mixing liver and brain microsomal preparations, or supernatants, there was no evidence for an inhibitory e...

Effects of external carbon sources and COD/NO(3)-N on nitrite accumulation through denitrification were studied at a temperature of 28±2.0 °C using mixed activated sludge. Nitrite accumulation was observed for each type of carbon source studied. Glucose resulted in the greatest nitrite accumulation and production rate, which were 14.51±2.41 mg/L and 0.121±0.013 g N/(g VSS d), respectively. More...

Neisseria meningitidis, the causative agent of meningococcal disease in humans, is likely to be exposed to nitrosative stress during natural colonization and disease. The genome of N. meningitidis includes the genes aniA and norB, predicted to encode nitrite reductase and nitric oxide (NO) reductase, respectively. These gene products should allow the bacterium to denitrify nitrite to nitrous ox...

Flavin reductase catalyzes the reduction of free flavins by NAD(P)H. As isolated, Escherichia coli flavin reductase does not contain any flavin prosthetic group but accommodates both the reduced pyridine nucleotide and the flavin substrate in a ternary complex prior to oxidoreduction. The reduction of riboflavin by NADPH catalyzed by flavin reductase has been studied by static and rapid kinetic...