When urea is added to Ureaplasma urealyticum, it is hydrolysed internally by a cytosolic urease. Under our measuring conditions, and at an external pH of 6.0, urea hydrolysis caused an ammonia chemical potential equivalent to almost 80 mV and, simultaneously, an increase in proton electrochemical potential (delta p) of about 24 mV with resultant de novo ATP synthesis. Inhibition of the urease w...

This study aimed to elucidate the strategies adopted by the African slender lungfish, Protopterus dolloi, to ameliorate the toxicity of ammonia during short (6 days) or long (40 days) periods of aestivation in a layer of dried mucus in open air in the laboratory. Despite decreases in rates of ammonia and urea excretion, the ammonia content in the muscle, liver, brain and gut of P. dolloi remain...

The x-ray crystal structure of the heterodimeric carbamoyl phosphate synthetase from Escherichia coli has identified an intermolecular tunnel that connects the glutamine binding site within the small amidotransferase subunit to the two phosphorylation sites within the large synthetase subunit. The tunneling of the ammonia intermediate through the interior of the protein has been proposed as a m...

Ammonia stress can inhibit the survival and growth, and even cause mortality of shrimp. In this study, ammonia-metabolizing enzyme activities and gene expression were compared between two strains of L. vannamei under different ammonia-N ([Formula: see text]) concentrations (3.4, 13.8, and 24.6 mg/L). The results showed that elevated ammonia concentrations mainly increased glutamine synthetase (...

A systematic study was carried out to investigate the potential of manganese nitride related materials for ammonia production. A-Mn-N (A= Fe, Co, K, Li) materials were synthesised by nitriding their oxide counterparts at low temperature using NaNH2 as a source of reactive nitrogen. The reactivity of lattice nitrogen was assessed using ammonia synthesis as a model reaction. In the case of Mn3N2,...

Orotic acid, first discovered in ruminant milk, is an intermediate in the pyrimidine biosynthesis pathway of animal cells. Its synthesis is initiated by the formation of carbamoyl phosphate (CP) in the cytoplasm, with ammonia derived from glutamine. Ureotelic species also form CP in the first step of urea synthesis in liver mitochondria. For that, ammonia is derived from tissue fluid. When ther...

The cerebral tricarboxylic acid (TCA) cycle rate and the rate of glutamine synthesis were measured in rats in vivo under normal physiological and hyperammonemic conditions using 13C NMR spectroscopy. In the hyperammonemic animals, blood ammonia levels were raised from control values of approximately 0.05 mM to approximately 0.35 mM by an intravenous ammonium acetate infusion. Once a steady-stat...

Ammonia removal is an important aspect of biological nutrient removal in wastewater treatment processes. However, due to process constraints, inhibiting compounds or more stringent discharge standards the ammonia removal rate can be insufficient. Subsequently, there is an increased need to optimize the functioning of existing treatment facilities. Addition of Archaea bio-systems to wastewater s...

Synchronization of rumen available protein and energy is one of the conceptual methods to increase the efficiency of utilization of nutrients by the ruminants The concept of synchronization energy and protein was first by Jhonson, Implying that maximum microbial protein synthesis could be achieved by matching the rate of Organic Matter and protein degradation. Synchronization of rumen available...

According to current concepts, renal ammonia synthesis may be attributed to the renal extraction and catabolism of certain plasma amino acids. In 1943, Van Slyke and associates demonstrated in the dog that the amide nitrogen of glutamine was removed from arterial plasma in quantities sufficient to account for approximately 60 per cent of the urinary ammonia excreted during metabolic acidosis (1...