Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.6.1.1 (aspartate aminotransferase)
21,665 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Comparative biochemical studies on phosphorylase b, aspartate aminotransferase and alanine aminotransferase in muscles of various vertebrates (the lamprey Lampetra fluviatilis, dogfish Squalus acanthias, rays Dasyatis pastinaca and Raja clavata, teleosts Scorpaena porcus, Spicara smaris, Esox lucius, Tinca tinca, Abramis brama, Lucioperca lucioperca, Cyprinus carpio, Salmo ischchan, frog Rana temporaria, tortoise Testudo horsfieldi) revealed some peculiarties of their molecular evolution. It was shown that isoenzyme PH-II, which comprises in most on the investigated lower vertebrates the main bulk of phosphorylase b, disappears in evolution of the type. Isoenzyme PH-I which is found in fisches in small amounts, increases in evolution becoming the sole form of phosphorylase b in skeletal muscles of endothermic animals. Mitochondrial and cytoplasmic isoenzymes of aspartate aminotransferase were found in all the vertebrates studied. Cytoplasmic isoenzyme from ectothermic and endothermic animals does not differ significantly, whereas the mitochondrial one undergoes considerable changes in the evolution of vertebrates.
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PMID:[Molecular evolution of glycogen phosphorylase and aminotransferases of vertebrate muscle tissue]. 1 51

The activities of hexokinase, glucose-6-phosphate dehydrogenase, and glycolytic enzymes were higher in the fetal myocardium of the guinea pig than at birth and fell progressively during the 1st mo of life. The alphaHBDH/LDH ratio of H to M subunits of lactate dehydrogenase, was low in the fetus and continued to rise during the 1st mo after birth. The distinction between the left and right ventricular activities of lactate dehydrogenase, which is clear in adult guinea pigs, was absent in the fetus and appeared during postnatal development. Glycogen phosphorylase activity was low in the fetus and at birth. The activities of beta-hydroxyacylcoenzyme A dehydrogenase, succinate dehydrogenase, malate dehydrogenase, and aspartate aminotransferase were low in the fetus, but had reached, or even temporarily exceeded, normal adult levels at birth. Palmitylcarnitine transferase activity was also low in the fetal heart compared with the newborn but continued to increase substantially during the first 2 wk after birth.
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PMID:Myocardial enzyme activities in guinea pigs during development. 59 69

The present study was undertaken to test the hypothesis that muscle phosphorylase may function as a repository for vitamin B6 in the animal. Since a repository would be expected to accumulate surplus material, one would predict that phosphorylase, which contains stoichio-metric amounts or pyridoxal phosphate, would increase in muscle of animals surfeited with the vitamin. Rats were fed a vitamin B6-free diet supplemented with pyridoxine providing levels 10, 1.0 and 0.1 of those recommended by the National Research Council (NRC). At the high intake level, muscle phosphorylase and total muscle vitamin B6 increased steadily and in almost constant ratio for at least 6 weeks, whereas both alanine and aspartate transaminase increased initially, but reached a plateau within 2 weeks. At the intermediate level of pyridoxine intake, muscle phosphorylase also increased, but less rapidly than in rats fed the higher level. When vitamin B6 intake was restricted to 10% of the NRC-recommended level, no increase in phosphorylase concentration occurred during a period of 10 weeks. These results support the hypothesis that muscle phosphorylase acts as a reservoir for vitamin B6 in the animal and provide experimental evidence that muscle enzyme content expands as vitamin is accumulated during high dietary intake.
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PMID:Increased muscle phosphorylase in rats fed high levels of vitamin B6. 90 52

Calmodulin, a low molecular weight Ca2+ binding protein, regulates a large number of cell activities including cell division. Previous studies from our laboratory indicated excessive accumulation of Ca2+ in hepatocytes succeeded by rapid glycogen breakdown and suppressed cell division in rats receiving CCl4 after previous dietary exposure to 10 ppm chlordecone. Since calmodulin plays a major role in Ca2(+)-regulated events and has been reported to be localized in mitotic apparatus during cell division, we have assessed subcellular distribution of calmodulin and estimated cytosolic phosphorylase a to indicate cytosolic free Ca2+ levels in livers of rats fed 0 ppm or 10 ppm (chlordecone) in the diet for 15 days before CCl4 (100 microliters/kg) administration to understand the role of Ca2(+)-calmodulin in chlordecone + CCl4 toxicity. Hepatotoxicity was assessed by determining serum AST and ALT succeeded by histopathological observations of liver sections. Serum aminotransferases were significantly elevated 6 hr after CCl4 administration to normal rats and returned to control level by 24 hr. However, serum AST and ALT elevations were severalfold higher, and progressive increase was observed starting 4 hr after CCl4 administration to chlordecone rats. Histopathological observations of liver sections for necrotic, swollen and lipid-laden cells provided findings commensurate with the serum enzyme data. These data indicate that normal rats do recover from CCl4 hepatotoxicity. However, the CCl4 hepatotoxicity is progressive in chlordecone rats without recovery. In normal rats, CCl4 administration resulted in a slight increase in phosphorylase a starting at 6 hr.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Carbon tetrachloride-induced alterations of hepatic calmodulin and free calcium levels in rats pretreated with chlordecone. 170 67

The purpose of the present study was to investigate the effects of 8 months of a specific and controlled sprint training programme on three groups of young athletes (two groups of males and one of females). Biopsies of vastus lateralis were taken before and after the period of training. The type percentage and diameter of the fibres, as well as the glycogen content and the activities of the enzymes of glycogen metabolism (glycogen synthase and glycogen phosphorylase), glycolysis (phosphofructokinase, pyruvate kinase, aldolase and lactate dehydrogenase), oxidative metabolism (succinate dehydrogenase) and creatine kinase and aminotransferases were studied. The results show an increase in the percentage of type I fibres and an increase in the diameter of both fibre types. A significant increase was also observed in glycogen content, and in the activities of glycogen synthase, glycogen phosphorylase, phosphofructokinase, pyruvate kinase, succinate dehydrogenase, aspartate aminotransferase and alanine aminotransferase. We conclude that a long period of sprint training induces a biochemical muscle adaptation to anaerobic exercise. This metabolic adaptation is followed by a morphological adaptation, although this is probably not as specific as the biochemical one.
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PMID:Biochemical and histochemical adaptation to sprint training in young athletes. 208 3

The erythrocyte aspartate aminotransferase and renal and intestinal glycogen phosphorylase activities in rats are determined as dependent on their provision with vitamin B6. It has been shown that the aspartate aminotransferase activity decreases and the shape of the aspartate concentration-activity curve changes in the vitamin B6-deficient animals. The B6 insufficiency does not affect the intestinal mucosa glycogen phosphorylase. However the renal phosphorylase activity decreases by 30 percent in the vitamin B6 deficient rats. It occurs due to changes in the affinity of phosphorylase A and B to glucose-1-phosphate but not to AMP. The activation of these investigated enzymes by exogenous pyridoxal phosphate reveals no essential differences between the vitamin B6-deficient and normal rats. The possible causes of the observed changes in the aspartate aminotransferase and phosphorylase activity are discussed.
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PMID:[Changes in kinetic properties of pyridoxal-dependent enzymes during dietary vitamin B6 deficiency in rats]. 211 Jun 92

The bloom forming cyanobacterium (blue-green alga) Nodularia spumigena produced a peptide hepatotoxin with an LD50 of 70 micrograms/kg i.p. in mice. The livers of lethally poisoned mice were haemorrhagic and enlarged, the weight doubling to about 10% of total body weight. Histologically there was centrilobular to midzonal disruption and lysis of hepatocytes resulting in haemorrhage and formation of blood lakes. Death occurred approximately 1 hr after i.p. injection. By 30 min significant increases had occurred in the plasma levels of lactate dehydrogenase, aspartate aminotransferase, alanine aminotransferase and glucose paralleling degeneration and necrosis of centrilobular hepatocytes. In vitro the toxin caused rapid dose-dependent deformation of freshly isolated rat hepatocytes, which was accompanied by the activation of phosphorylase a; 125 ng/ml of toxin being sufficient to cause these changes in 10(6) cells. This work demonstrates that, both in vivo and in vitro, Nodularia toxin shares many similarities in its action to the well characterized peptide toxins of another cyanobacterium, Microcystis aeruginosa.
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PMID:Toxicity of the cyanobacterium Nodularia spumigena Mertens. 312 24

The study of patterns of serum AST, ALT, CPK, LDH, and glycogen phosphorylase (GP) activity following bicycle ergometry in 26 male patients 1 to 1.5 months after myocardial infarction demonstrated no increase in AST, ALT and CPK activity, whereas total LDH activity was increased, with a tendency to elevated LDH-1 and LDH-2 fractions, as compared to the baseline, in those cases where exercise was discontinued because of ST depression. Patients with favorable response to bicycle ergometry that continued until the submaximum heart rate for a given age was achieved showed a tendency to elevated LDH-5 that may be a physiological response to exercise. The demonstrated increase in total GP activity, both in patients with exercise-induced ST depression and in those with elevated ST from the leads corresponding to the site of myocardial infarction, may reflect stress-induced reversible ischemia.
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PMID:[Effect of physical loading on serum enzyme activity in post-myocardial infarct patients]. 370 99

1. The activities of gluconeogenic and glycolytic enzymes and the concentrations of citrate, ammonia, amino acids, glycogen, glucose 6-phosphate, acetyl-CoA, lactate and pyruvate were measured in kidney cortex of normal, diabetic, cortisone-treated and growth hormone-treated rats. 2. In kidney cortex of diabetic, cortisone-treated and growth hormone-treated rats the activities of glucose 6-phosphatase (EC 3.1.3.9), fructose 1,6-diphosphatase (EC 3.1.3.11) and phosphopyruvate carboxylase (EC 4.1.1.32) were increased. 3. The activities of glutamate dehydrogenase (EC 1.4.1.3), alanine aminotransferase (EC 2.6.1.2), aspartate aminotransferase (EC 2.6.1.10) and pyruvate carboxylase (EC 6.4.1.1) were increased in diabetic and cortisone-treated rats. In growth hormone-treated rats the activity of aspartate aminotransferase was depressed but those of the other three enzymes were unchanged. 4. The activity of hexokinase (EC 2.7.1.1) was not altered in any of these conditions. Phosphofructokinase (EC 2.7.1.11) activity was depressed only in growth hormone-treated rats. Pyruvate kinase (EC 2.7.1.40) activity was depressed in cortisone-treated and growth hormone-treated rats but unchanged in diabetic rats. 5. Amino acids, acetyl-CoA and glucose 6-phosphate contents were increased in rat kidneys in all these three conditions. Ammonia content was increased in diabetic and cortisone-treated rats but was markedly diminished in growth hormone-treated rats. 6. The [lactate]/[pyruvate] ratio was elevated in diabetic and cortisone-treated rats but unchanged in growth hormone-treated rats. Citrate content was increased in the kidney cortex of diabetic and growth hormone-treated rats but was unchanged in cortisone-treated rats. The activity of ATP citrate lyase (EC 4.1.3.8) was depressed in diabetic and growth hormone-treated rats but was increased in cortisone-treated rats. 7. Glycogen content was moderately elevated in growth hormone-treated rats and markedly elevated in diabetic rats, whereas no change in glycogen content was observed in cortisone-treated rats. Glycogen synthetase (EC 2.4.1.11) activity was unchanged in all these three conditions. Phosphorylase (EC 2.4.1.1) activity was not affected in cortisone-treated rats but was depressed in diabetic and growth hormone-treated rats.
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PMID:Evaluation of the rate-limiting steps in the pathway of glucose metabolism in kidney cortex of normal, diabetic, cortisone-treated and growth hormone-treated rats. 434 56

Inactivation of the beta 2 subunit and of the alpha 2 beta 2 complex of tryptophan synthase of Escherichia coli by the arginine-specific dicarbonyl reagent phenylglyoxal results from modification of one arginyl residue per beta monomer. The substrate L-serine protects the holo beta 2 subunit and the holo alpha 2 beta 2 complex from both inactivation and arginine modification but has no effect on the inactivation or modification of the apo forms of the enzyme. This result and the finding that phenylglyoxal competes with L-serine in reactions catalyzed by both the holo beta 2 subunit and the holo alpha 2 beta 2 complex indicate that L-serine and phenylglyoxal both bind to the same essential arginyl residue in the holo beta 2 subunit. The apo beta 2 subunit is protected from phenylglyoxal inactivation much more effectively by phosphopyridoxyl-L-serine than by either pyridoxal phosphate or pyridoxine phosphate, both of which lack the L-serine moiety. The phenylglyoxal-modified apo beta 2 subunit binds pyridoxal phosphate and the alpha subunit but cannot bind L-serine or L-tryptophan. We conclude that the alpha-carboxyl group of L-serine and not the phosphate of pyridoxal phosphate binds to the essential arginyl residue in the beta 2 subunit. The specific arginyl residue in the beta 2 subunit which is protected by L-serine from modification by phenyl[2-14C]glyoxal has been identified as arginine-148 by isolating a labeled cyanogen bromide fragment (residues 135-149) and by digesting this fragment with pepsin to yield the labeled dipeptide arginine-methionine (residues 148-149). The primary sequence near arginine-148 contains three other basic residues (lysine-137, arginine-141, and arginine-150) which may facilitate anion binding and increase the reactivity of arginine-148. The conservation of the arginine residues 141, 148, and 150 in the sequences of tryptophan synthase from E. coli, Salmonella typhimurium, and yeast supports a functional role for these three residues in anion binding. The location and role of the active-site arginyl residues in the beta 2 subunit and in two other enzymes which contain pyridoxal phosphate, aspartate aminotransferase and glycogen phosphorylase, are compared.
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PMID:L-serine binds to arginine-148 of the beta 2 subunit of Escherichia coli tryptophan synthase. 641 46


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