Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.4.1.4 (glutamate dehydrogenase)
 4,358 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Synthesis of wild-type Neurospora crassa assimilatory nitrate reductase is induced in the presence of nitrate ions and repressed in the presence of ammonium ions. Effects of several Neurospora mutations on the regulation of this enzyme are shown: (i) the mutants, nit-1 and nit-3, involving separate lesions, lack reduced nicotinamide adenine dinucleotide (NADPH)-nitrate reductase activity and at least one of three other activities associated with the wild-type enzyme. The two mutants do not require the presence of nitrate for induction of their aberrant nitrate reductases and are constitutive for their component nitrate reductase activities in the absence of ammonium ions. (ii) An analog of the wild-type enzyme (similar to the nit-1 enzyme) is formed when wild type is grown in a medium in which molybdenum has been replaced by vanadium or tungsten; the resulting enzyme lacks NADPH-nitrate reductase activity. Unlike nit-1, wild type produced this analog only in the presence of nitrate. Contaminating nitrate does not appear to be responsible for the observed mutants' activities. Nitrate reductase is proposed to be autoregulated. (iii) Mutants (am) lacking NADPH-dependent glutamate dehydrogenase activity partially escape ammonium repression of nitrate reductase. The presence of nitrate is required for the enzyme's induction. (iv) A double mutant, nit-1 am-2, proved to be an ideal test system to study the repressive effects of nitrogen-containing metabolites on the induction of nitrate reductase activity. The double mutant does not require nitrate for induction of nitrate reductase, and synthesis of the enzyme is not repressed by the presence of high concentrations of ammonium ions. It is, however, repressed by the presence of any one of six amino acids. Nitrogen metabolites (other than ammonium) appear to be responsible for the mediation of "ammonium repression."
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PMID:Induction and repression of nitrate reductase in Neurospora crassa. 14

The efficacy of a molybdate formulation and a zinc oxide bolus as prophylactic agents for enzootic icterus was evaluated in sheep. Before copper loading, liver biopsies were performed on 12 male, 6-month-old, Mutton Merino sheep to determine hepatic copper (Cu) and zinc (Zn) concentrations. The animals were restrictively randomised according to liver copper concentrations to 3 treatment groups (n = 4) to achieve similar mean liver copper concentrations per group. All sheep received 4 ml/kg of a 0.5 % aqueous solution of CuSO4 5H2O intraruminally 7 days per week for 10 weeks. On Day 0 the sheep in the Mo-group were injected subcutaneously with 42 mg molybdenum (Mo) contained in a commercial molybdate formulation. The animals in the Zn-group each received a zinc oxide bolus, containing 43 g zinc oxide, via a rumen cannula. Treatment was repeated on Day 42. Four animals served as untreated controls. Urinary copper excretion, plasma copper concentration, haematocrit and glutamate dehydrogenase (GLDH) activity were determined throughout the trial. The animals were sacrificed after 10 weeks and liver samples were submitted for histopathological examination. Liver and kidney copper and zinc concentrations were determined. Neither the molybdate treatment nor the zinc oxide boluses prevented hepatic copper accumulation. The urinary copper excretion, plasma copper concentration, haematocrit and GLDH activity were not significantly different (P > 0.05) from the controls.
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PMID:Evaluation of a commercially available molybdate formulation and zinc oxide boluses in preventing hepatic copper accumulation and thus enzootic icterus in sheep. 1221 12

Patients affected by sulfite oxidase (SO) deficiency present severe seizures early in infancy and progressive neurological damage, as well as tissue accumulation of sulfite, thiosulfate and S-sulfocysteine. Since the pathomechanisms involved in the neuropathology of SO deficiency are still poorly established, we evaluated the effects of sulfite on redox homeostasis and bioenergetics in cerebral cortex, striatum, cerebellum and hippocampus of rats with chemically induced SO deficiency. The deficiency was induced in 21-day-old rats by adding 200ppm of tungsten, a molybdenum competitor, in their drinking water for 9weeks. Sulfite (70mg/kg/day) was also administered through the drinking water from the third week of tungsten supplementation until the end of the treatment. Sulfite decreased reduced glutathione concentrations and the activities of glutathione reductase and glutathione S-transferase (GST) in cerebral cortex and of GST in cerebellum of SO-deficient rats. Moreover, sulfite increased the activities of complexes II and II-III in striatum and of complex II in hippocampus, but reduced the activity of complex IV in striatum of SO-deficient rats. Sulfite also decreased the mitochondrial membrane potential in cerebral cortex and striatum, whereas it had no effect on mitochondrial mass in any encephalic tissue evaluated. Finally, sulfite inhibited the activities of malate and glutamate dehydrogenase in cerebral cortex of SO-deficient rats. Taken together, our findings indicate that cerebral cortex and striatum are more vulnerable to sulfite-induced toxicity than cerebellum and hippocampus. It is presumed that these pathomechanisms may contribute to the pathophysiology of neurological damage found in patients affected by SO deficiency.
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PMID:Higher susceptibility of cerebral cortex and striatum to sulfite neurotoxicity in sulfite oxidase-deficient rats. 2752 30