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)

1. The cultured, epimastigote-form of Trypanosoma cruzi contains NADP-linked glutamate dehydrogenase (EC 1.4.1.4), with a molecular weight of about 280,000, similar to the enzyme from Plasmodium chabaudi and different from the enzymes from higher animal sources. 2. T. cruzi also contains aspartate aminotransferase (EC 2.6.1.1), with properties similar to those of the enzyme from mammals. 3. The concerted action of the transaminase and glutamate dehydrogenase might be responsible for the production of NH3 which characterizes the protein catabolism in T. cruzi.
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PMID:Glutamate dehydrogenase and aspartate aminotransferase in Trypanosoma cruzi. 40 Sep 47

In experiments on 6 sheep the authors found the following enzyme activities in bacteria in the rumen fluid, bacteria adhering to the epithelium of the rumen wall and bacteria adhering to food particles in the rumen (given in nkat X g-1 bacterial dry weight): GDH (NADH): 725 +/- 165, 558 +/- 127, 661 +/- 153; GDH (NADPH): 558 +/- 338, 255 +/- 88, 565 +/- 139; GOAT (NADH): 46 +/- 23, 67 +/- 31, 66 +/- 14; GOGAT/NADPH: 58 +/- 27, 56 +/- 15, 65 +/- 29; GS: 153 +/- 65, 69 +/- 35, 71 +/- 32; ALT: 71 +/- 25, 43 +/- 20, 52 +/- 11; AST: 52 +/- 12, 33 +/- 16, 28 +/- 15. The results show that, except for GDH (NADPH), there were no significant differences between the given enzyme activities in the rumen fluid and in bacteria adhering to the rumen wall and to food. Adherent rumen bacteria have the same potential possibilities as the rumen fluid bacteria for the utilization of ammonia, particularly for the synthesis of glutamic acid, glutamine, alanine and aspartic acid, with the above enzymes as catalysts. By means of the GS/GOGAT system, adherent rumen bacteria can probably synthesize glutamic acid in the presence of a limited NH3 concentration in the rumen.
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PMID:Ammonia-utilizing enzymes of adherent bacteria in the sheep's rumen. 286 70

The spatial structure of cytosolic chicken aspartate aminotransferase (AAT) has been determined by X-ray crystallographic analysis at 2.8 A resolution. AAT consists of two chemically identical subunits. Each subunit can be subdivided into the large pyridoxal phosphate (PLP) binding domain and the small domain. The two active sites of AAT are situated in deep clefts at the subunit interface. The binding of PLP and 2-oxoglutarate is described. Conformations of the following enzyme forms have been compared by difference Fourier syntheses: the nonliganded PLP-form in phosphate and acetate buffers; the non-liganded pyridoxamine phosphate (PMP) form; complexes of the PLP-form with glutarate and 2-oxoglutarate. Lattice-induced dynamic asymmetry of the dimeric AAT molecules was revealed. In one subunit the small domain is mobile and shifted either toward the active site ("closed" conformation) or in the opposite direction ("open" conformation). The closed conformation is induced by the binding of dicarboxylate anions. In the second subunit the small domain is immobile and shifted toward the active site in all enzyme forms or complexes studied. In this subunit, there occurs a rotation of the PLP ring by approximately 20 degrees toward the substrate site. The rotation is observed when crystals are soaked in 0.6 saturated (NH4)2SO4 solution buffered with 0.3 M potassium phosphate, pH 7.5; it was explained by formation of an external aldimine between PLP and NH3. This aldimine is not formed in the presence of dicarboxylates or acetate. It was inferred that dicarboxylate or acetate anions stabilize the internal PLP-lysine aldimine and prevent its reaction with ammonia. Conversion of AAT from the PLP- to PMP-form is accompanied by rotation of the coenzyme ring by approximately 20 degrees; the rotation occurs in both subunits.
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PMID:[Cytosol aspartate aminotransferase from the chicken heart: three-dimensional structure at 2.8 angstroms resolution and the characteristic conformation of various enzyme forms]. 398 8

The activity of certain key enzymes involved in glutamic acid metabolism was studied in purified brain mitochondria and in mitochondrial subfractions separated in a discontinuous 1.2--1.6 mol/l sucrose gradient. Alanine aminotransferase and glutamate dehydrogenase were found to be matrix enzymes and aspartate aminotransferase to be associated with the inner mitochondrial membranes. After the purified mitochondria had been separated into 5 subfractions, aspartate aminotransferase and NAD+-dependent isocitrate dehydrogenase were found to be bound to the lighter mitochondrial subfractions settling at the 1.4--1.5 mol/l sucrose boundary while alanine aminotransferase, 4-aminobutyrate transaminase and glutamate dehydrogenase were associated with the heavier subfractions settling below 2.4 mol/l sucrose. The highest specific activity of the given enzymes was found in the subfraction settling at the 1.4--1.5 mol/l sucrose boundary, the only exception being alanine aminotransferase activity, whose maximum was found in the subfractions settling in 1.5 and 1.6 mol/l sucrose. It was concluded that alanine aminotransferase, in conjunction with glutamate dehydrogenase, is linked to NH3 binding and to the oxidation of reduced adenine nucleotides; in addition, alanine aminotransferase is presumed to have the function of transporting glutamate from the mitochondria to the extramitochondrial space.
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PMID:Alanine aminotransferase and some other enzymes in different populations of free brain cortex mitochondria. 645 52

Muscle ATP loss with exercise has implications both to the causes of fatigue and muscle damage. To study this at the single muscle fibre level, five trained thoroughbred horses performed consecutive 90 second gallops on an inclined treadmill followed by a final gallop to fatigue. Biopsies of the m. gluteus medius were taken at rest, post-exercise and during 24 hour recovery. Blood lactate was 20.0 mmol litre-1 or more, and plasma NH3 300-800 mumol litre-1, following the final gallop. Minimal changes occurred in the plasma markers, CK and AST. ATP loss with exercise was 32.2 (SD 12.2) per cent. Following exercise single fibre ATP contents showed a much broader distribution than at rest, with contents in some close to zero. Following five and 24 hour recovery, however, frequency distribution curves were close to those seen at rest. There was no difference in the ATP contents of types I, IIa and IIb at rest of with exercise or recovery. The results pointed to marked heterogeneity between individual fibres in their biochemical response with exercise, independent of fibre type.
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PMID:ATP loss with exercise in muscle fibres of the gluteus medius of the thoroughbred horse. 949 49

The mass transfers of O2, glucose, NH3, urea and amino acids across the portal-drained viscera (PDV) and the liver were quantified, by arterio-venous techniques, during the last 4 h of a 100 h infusion of 0 (basal), 150 or 400 mumol NH4HCO3/min into the mesenteric vein of three sheep given 800 g grass pellets/d and arranged in a 3 x 3 Latin-square design. Urea irreversible loss rate (ILR) was also determined by continuous infusion of [14C]urea over the last 52 h of each experimental period. PDV and liver movements of glucose, O2 and amino acids were unaltered by NH4HCO3 administration, although there was an increase in PDV absorption of non-essential amino acids (P = 0.037) and a trend for higher liver O2 consumption and portal appearance of total amino acid-N, glucogenic and non-essential amino acids at the highest level of infusion. PDV extraction of urea-N (P = 0.015) and liver removal of NH3 (P < 0.001), release of urea-N (P = 0.002) and urea ILR (P = 0.001) were all increased by NH4HCO3 infusion. Hepatic urea-N release (y) and NH3 extraction (x) were linearly related (R2 0.89), with the slope of the regression not different from unity, both for estimations based on liver mass transfers (1.16; SE 0.144; P(b) not equal to 1 = 0.31) and [14C]urea (0.97; SE 0.123; P(b) not equal to 1 = 0.84). The study indicates that a sustained 1.5 or 2.4-fold increase in the basal NH3 supply to the liver did not impair glucose or amino acid supply to non-splanchnic tissues; nor were additional N inputs to the ornithine cycle necessary to convert excess NH3 to urea. Half of the extra NH3 removed by the liver was, apparently, utilized by periportal glutamate dehydrogenase and aspartate aminotransferase for sequential glutamate and aspartate synthesis and converted to urea as the 2-amino moiety of aspartate.
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PMID:Influence of hepatic ammonia removal on ureagenesis, amino acid utilization and energy metabolism in the ovine liver. 1088 19

Biochemical changes, total proteins, glycogen, aspartate and alanine (AAT and ALAT) amino transferases were studied with exposure of sublethal concentrations of NH3-N, NO2-N and NO3-N to the freshwater fish Catla catla (Hamilton), Labeo rohita (Hamilton) and Cirrhinus mrigala (Hamilton). Depletion in the food reserves and enzyme activity was observed in all the three fish species exposed to these toxicants. Hence, the concentrations of NH3, NO2 and NO3 in water need to be monitored in water quality in aquaculture practices.
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PMID:Studies of some biochemical changes in the tissues of Catla catla (Hamilton), Labeo rohita (Hamilton) and Cirrhinus mrigala (Hamilton) exposed to NH3-N, NO2-N and NO3-N. 1267 77

There have been many fatal occupational accidents of skin exposure to monochloroacetic acid (MCA). However, there have been no reports of dermatological findings and the lethal consequences have not yet been demonstrated. Therefore, harmful local and systemic effects were investigated after dermal exposure to MCA. A 0.5 mL aliquot of MCA solution (40% w/w) was applied to the abdominal skin of ten 10-week-old male SD rats under anesthesia. The exposure area (25 x 25 mm2) was 1.6% of the total surface area. The dose of MCA per area was 34.1 mg/cm2. Saline was similarly administered to 10 control rats. Histopathological findings after 10 min were observed by light microscopy. Blood samples were collected by exsanguinations from the carotid arteries after 4 h. Skin samples were collected 10 min after the initial exposure. Histological findings showed severe degeneration of collagen bundles in the epidermis and subcutaneous tissues. P(CO2), HCO(3)-, TCO2, BE and glucose levels were decreased in the MCA group. AST, m-AST, ALT, BUN, Cr, NH3, lactic acid, pyruvic acid, RBC, Hb, Hct, total protein and albumin were increased in the MCA group. The burn was determined to be a third-degree burn on the basis of the histopathological findings. The severe toxicity was probably a consequence of the rapid permeability. Biochemical parameters were a consequence of hepatocellular injuries, renal dysfunction, dysglyconeogenesis and dysfunction of ammonia metabolism. MCA reportedly enters the TCA cycle and inhibits aconitase. MCA metabolites also inhibit pyruvate carboxylase in the gluconeogenesis pathway. Therefore, the important serum biochemical abnormalities such as hypoglycemia and lactic acidosis should be monitored to find the acute systemic disorders.
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PMID:Systemic effects and skin injury after experimental dermal exposure to monochloroacetic acid. 1574 77

Twenty-four growing male buffalo calves (one year of age; 88.54 +/- 3.81 kg average body weight) were divided into three comparable groups (I, II and III) on the basis of their body weight (BW) in a completely randomised design to study the effect of long term feeding of ammoniated wheat straw (AWS) and hydrochloric acid treated ammoniated wheat straw (HCl-AWS) on blood biochemical changes. The animals were offered a concentrate mixture (CM) along with wheat straw (WS), ammoniated wheat straw (AWS) (4% urea at a 50% moisture level) and hydrochloric acid treated ammoniated wheat straw (HCI-AWS) (4% urea at a 50% moisture level and HCI added to trap 30% of NH3 evolved) in groups I, II and III, respectively for an average daily gain (ADG) of 500 g. All the diets were made iso-nitrogenous by preparing three types of concentrate mixtures of different CP levels. The blood was collected from the jugular vein randomly from three animals of each group initially after 8 months post feeding and subsequently after two months interval up to 14 months of experimental feeding. Due to urea ammoniation, the CP content of WS increased from 3.66 to 8.51 and was further increased to 11.35 due to the addition of HCl during urea-ammoniation of wheat straw. The cumulative period mean plasma glucose values (mg %), in group II (53.13) were significantly (P < 0.001) higher than those in groups I (48.44) and III (50.60). The cumulative period mean values of serum albumin and globulin (g %) were not significantly different and were comparable among the groups I (3.33 and 3.06), II (3.53 and 2.97) and III (3.49 and 2.94). The cumulative period mean values of serum albumin: globulin ratio and total protein values were not significantly different among the different groups. Serum urea and creatinine values were significantly (P < 0.001) higher in group III (58.66 and 2.24) as compared to groups I and II. The cumulative period mean values of serum alkaline phosphatase (ALP) (KA units) did not differ significantly, but serum glutamate pyruvate transaminase (SGPT) and glutamate oxaloacetate transaminase (SGOT) values (units x mL(-1) were significantly (P < 0.001) higher in groups II and III than in group I. The cumulative period mean values of T3 (ng x mL(-1)) did not differ significantly among the groups, but T4 values were significantly (P < 0.001) higher in group III (22.74) than in groups 1 (21.41) and II (20.89), respectively. Since the mean values of all the blood parameters were within the normal range, it may be concluded that feeding of ammoniated wheat straw treated with and without HCl to growing male buffalo calves for fourteen months has no adverse effect on the blood biochemical parameters.
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PMID:Effect of long term feeding of ammoniated wheat straw treated with or without HCl on blood biochemical parameters in growing male buffalo (Bubalus bubalis) calves. 1595 22

Seven dairy cows fitted with ruminal and duodenal cannulae were used to investigate the influence of the amount of ruminally available N (Ruminal N-Balance, RNB) on the rumen metabolism and to answer the question on the lowest N-amount in the rumen, without negative effects on the fermentation. Animals were fed a ration on the basis of 7.9 kg corn silage and 7.2 kg concentrates related to dry matter, intended to meet the animals mean NEL and protein requirements. RNB amounted to -0.6 g/MJ ME in the basis ration. The other 3 rations were adjusted to RNB-values of -0.3, 0 and + 0.3 g/MJ ME by urea supplements in the concentrates. The increase in RNB resulted in higher NH3-N concentrations in the rumen fluid and in the duodenal digesta and higher urea concentrations in the blood and milk. The significantly highest amount of protein at the duodenum was detected when RNB showed an equilibrium (RNB = 0). The efficiency of microbial protein (MP) synthesis (gMP/kg fermented organic matter) was the same, g MP/d and g MP/MJ ME were significantly lower with RNB = -0.6g/MJ ME as compared to RNB = 0. The group with thelowest RNB showed the highest level of feedprotein degradation as well as the lowest organic matter, NDF and ADF fermentation. An effect on cholesterol, total bilirubin and gammaGT due to different RNB was not detected. The activities of GLDH and AST were highest when the RNB was -0.6 g/MJ ME. From the results, it can be concluded that significantly negative effects on rumen fermentation occur when RNB-values are below -0.3 g/MJ ME. However, a positive RNB did not increase t he degradation and synthesis capacity of the rumen micro-organisms as compared to RNB = 0.
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PMID:Investigations on the effect of the ruminal N-balance on rumen metabolism, urea content in blood serum and milk as well as some liver parameters of lactating cows. 1664 73


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