Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.4.1.2 (glutamate dehydrogenase)
 4,380 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Alanine dehydrogenase (AlaDH: EC 1.4.1.1), malate dehydrogenase (MDH: EC 1.1.1.37), and glutamate dehydrogenase (EC 1.4.1.2), all NAD+ dependent, were detected in extracts from a psychrophilic bacterium, strain PA-43, isolated from a sea urchin off the Icelandic coast. Characterization tests suggested that the strain had a close relationship to Vibrio, but sequencing of part of the 16S rDNA gene placed the bacterium among Shewanella species in a constructed phylogenetic tree. The bacterium had an optimum growth temperature of 16.5 degrees C, and maximum dehydrogenase expression was obtained in a rich medium supplemented with NaCl. Both AlaDH and MDH were purified to homogeneity. AlaDH is a hexamer, with an approximate relative molecular mass of 260,000, whereas MDH is dimeric, with an apparent relative molecular mass of approximately 70,000. Both enzymes were thermolabile, and the optimum temperatures for activity were shifted toward lower temperatures than those found in the same enzymes from mesophiles, 37 degrees C for MDH and approximately 47 degrees C for AlaDH. The pH optima for AlaDH in the forward and reverse reactions were 10.5 and 9, respectively, whereas those for MDH were 10-10.2 and 8.8, respectively. Partial amino acid sequences, comprising approximately 30% of the total sequences from each enzyme, were determined for N-terminal, tryptic, and chymotryptic fragments of the enzymes. The AlaDH showed the highest similarity to AlaDHs from the psychrotroph Shewanella Ac10 and the mesophile Vibrio proteolyticus, whereas MDH was most similar to the MDHs from the mesophiles Escherichia coli and Haemophilus influenzae, with lower identity to the psychrophilic malate dehydrogenases from Vibrio 5710 and Photobacterium SS9.
 ...
PMID:Characterization of alanine and malate dehydrogenases from a marine psychrophile strain PA-43. 1145 64

The freshwater snakehead Channa asiatica is an obligatory air-breather that resides in slow-flowing streams and in crevices near riverbanks in Southern China. In its natural habitat, it may encounter bouts of aerial exposure during the dry seasons. In the laboratory, the ammonia excretion rate of C. asiatica exposed to terrestrial conditions in a 12 h:12 h dark:light regime was one quarter that of the submerged control. Consequently, the ammonia contents in the muscle, liver and plasma increased significantly, and C. asiatica was able to tolerate quite high levels of ammonia in its tissues. Urea was not the major product of ammonia detoxification in C. asiatica, which apparently did not possess a functioning ornithine urea cycle. Rather, alanine increased fourfold to 12.6 micromol g(-1) in the muscle after 48 h of aerial exposure. This is the highest level known in adult teleosts exposed to air or an ammonia-loading situation. The accumulated alanine could account for 70% of the deficit in ammonia excretion during this period, indicating that partial amino acid catabolism had occurred. This would allow the utilization of certain amino acids as energy sources and, at the same time, maintain the new steady state levels of ammonia in various tissues, preventing them from rising further. There was a reduction in the aminating activity of glutamate dehydrogenase from the muscle and liver of specimens exposed to terrestrial conditions. Such a phenomenon has not been reported before and could, presumably, facilitate the entry of alpha-ketoglutarate into the Krebs cycle instead of its amination to glutamate, as has been suggested elsewhere. However, in contrast to mudskippers, C. asiatica was apparently unable to reduce the rates of proteolysis and amino acid catabolism, because the reduction in nitrogenous excretion during 48 h of aerial exposure was completely balanced by nitrogenous accumulation in the body. Alanine accumulation also occurred in specimens exposed to terrestrial conditions in total darkness, with no change in the total free amino acid content in the muscle. Exercise on land led to a decrease in glycogen content, and an increase in lactate levels, with no significant effect on ammonia and alanine contents in the muscle of C. asiatica. Hence, unlike the mudskipper Periophthalmodon schlosseri, C. asiatica was incapable of increasing the rate of partial amino acid catabolism to sustain locomotory activities on land. Alanine formation therefore appears to be a common strategy adopted by obligatory air-breathing fishes to avoid ammonia toxicity (not a strategy to detoxify ammonia) on land, but not all of them can utilize it to fuel muscular activities.
 ...
PMID:The snakehead Channa asiatica accumulates alanine during aerial exposure, but is incapable of sustaining locomotory activities on land through partial amino acid catabolism. 1251 87

Mitochondrial Krebs cycle keto acid pool depends upon input from pyruvate and glutamate to maintain homeostasis. We studied the affect of glucose-derived pyruvate removal on compensatory input from glutamine-derived glutamate by accelerated glutamate metabolism via glutamate dehydrogenase (GDH). In glutamine minus glucose media (Gln-Glc), NH(4)(+) production increased 41% without an increase in glutamine uptake consistent with accelerated glutamate metabolism via GDH. Alanine production dropped 40% consistent with a shift of glutamate from alanine aminotransferase (ALT) to GDH. Troglitazone (TRO) added to the Gln-Glc media further enhanced glutamate metabolism via GDH at the expense of glutamate metabolism via ALT since alanine production dropped an additional 70%. TRO reduced cell glutamate content 30% while increasing lactate production 5-fold consistent with blocking of cytosolic pyruvate formed from mitochondrial malate from reentering the cycle and maintaining keto acid pool homeostasis. Consequently mitochondrial keto acid pool deficit pulls glutamate via GDH into the cycle. Additionally TRO reduced cytosolic pH which effectively pushes glutamate via GDH, rather than merely shifting glutamate from ALT to GDH. Providing intramitochondrial pyruvate in the form of methyl pyruvate reduced glutamate metabolism via GDH and elevated glutamate metabolism via ALT to control levels restoring acid-base balance. Our findings are consistent with TRO regulation of anaplerosis dependent upon dual pull (cycle keto-acid deficit)/push (cytosolic acidosis) mechanisms.
 ...
PMID:Troglitazone regulates anaplerosis via a pull/push affect on glutamate dehydrogenase mediated glutamate deamination in kidney-derived epithelial cells; implications for the Warburg effect. 2106 99


<< Previous 1 2 3