Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P17174 (aspartate aminotransferase)
 14,872 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The levels of several enzymes have been studied during sporulation of Saccharomyces cerevisia. The specific activities of ribonuclease and aminopeptidase I raised several-fold after transfer of the cells to sporulation medium, whereas the specific activities of phosphofructokinase, glucose-6-phosphate dehydrogenase, tryptophan synthase and pyruvate decarboxylase were not significantly altered. The specific activities of NAD-dependent glutamate dehydrogenase, isocitrate lyase, malate dehydrogenase and fructose bisphosphatase all decreased from the onset of sporulation. The inactivation of these latter enzymes was inhibited by cycloheximide and by inhibitors of energy metabolism. Hexokinase, alcohol dehydrogenase and glutamate oxaloacetate transaminase were partially lost from the cells during the period of ascus maturation. None of the enzyme changes observed proved to be 'sporulation-specific' in that it occurred exclusively in sporulating diploid yeast cells. Therefore it is postulated that the meiotic events and the metabolic changes required for ascospore formation are under separate genetic control in this organism. During sporulation, the cellular content of cytochromes b, c, and aa3 was reduced to 20% or less of that present in vegetative derepressed cells. Since the relative percentage of total to cycloheximide-insensitive mitochondrial protein synthesis was not significantly altered throughout sporulation, and the pattern of mitochondrially synthesized polypeptides was rather similar both in vegetative and in sporulating cells, it appeared that not only degradation but also synthesis and therefore turnover of the mitochondrially coded polypeptides of cytochromes b and aa3 took place during sporulation. The activity ratio of cytochrome c oxidase to F1-ATPase in submitochondrial particles isolated from vegetative cells and from purified asci was almost identical. This indicates that the loss of membrane-bound mitochondrial cytochromes during sporulation is probably due to a nonselective degradation of inner mitochondrial membrane proteins.
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PMID:Protein degradation during yeast sporulation. Enzyme and cytochrome patterns. 18 44

Soluble and membrane-bound aminopeptidase activities in eleven regions of the rat brain were assayed using L-leucine-2-naphthylamide as a substrate. In addition, two metabolic enzymatic activities were compared: lactate dehydrogenase and aspartate aminotransferase. All enzymatic activities showed significant regional differences when the data were analyzed statistically. Soluble aminopeptidase and aspartate aminotransferase activities were significantly lower in cortical than in subcortical areas. Membrane-bound aminopeptidase activity levels were higher in cortical areas. Lactate dehydrogenase activities did no differ between cortical areas and the rest of the zones studied. However, while no wide regional differences were found for the other enzymatic activities, membrane-bound aminopeptidase varied markedly across brain regions: a 5-fold difference was observed between zones. The differential distribution of this enzymatic activity is consistent with the hypothesis that it is responsible for the enzymatic inactivation of some neuroactive peptides.
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PMID:[Regional distribution of brain aminopeptidases in the rat]. 130 96

In 93 alcohol dependent patients following laboratory tests were done: gamma-glutamic transpeptidase (GGTP), aspartate aminotransferase (SGOT), mean erythrocyte volume (MCV), triglycerides (TGL), and HDL-cholesterol to whole-cholesterol ratio (HDLC%). The psychometric evaluation was made by MAST questionnaire and by authors clinical scale for the evaluation of alcohol dependence. Lover values of GGTP and SGOT were shown in patients during abstinence than in subjects continuing drinking. Patients more severely dependent showed higher HDLC%. The more frequent abnormalities reflected: GGTP (33.7%), MCV (33.7%), and HDLC (31.4%). The use of these 3 markers allowed to reveal abnormalities in 72.1% of subjects, while the use of all 5 markers - in 81.4%. The identification significance of markers was different in persons with more and less severe alcohol dependence. Three most sensible markers in the group of less dependent subjects were GGTP, MCV, TGL (60% of subjects showed abnormalities regarding these markers). Among more severe dependent subjects HDLC%, GGTP, and MCV were most sensible markers (78.4% of abnormalities). Using all 5 markers the abnormalities in the group of less severe dependent subjects were found in 71.4%, and in the group of more severe dependent patients--in 88.2%.
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PMID:[Biochemical markers in relation to the degree of alcohol dependence]. 198 82

Two isozymes of aspartate aminotransferase have been demonstrated biochemically. One isozyme is found in the mitochondrial fraction of the cytoplasm, the other ("soluble") in the supernatant. Both isozymes can be demonstrated by the cytochemical technique of Lee and Torack, as reported in the preceding report. Aldehyde fixation rapidly inactivates both isozymes, especially the soluble one. Inactivation can be delayed by addition of ketoglutarate to the fixative. The ketoglutarate probably competes with the fixative for the active site of the enzyme, thus protecting that region of the molecule. This enables adequate tissue preservation with enough remaining enzymatic activity to be demonstrated by the precipitation of oxaloacetate as the lead salt from a medium containing alpha-ketoglutaric acid aspartic acid, and lead nitrate. Electron-opaque material was found not only in mitochondria but, as the result of substrate protection, on the plasma membranes of many cells including erythrocytes and bacteria, the limiting membrane of peroxisomes, and the transverse tubular system of striated muscle. Occasional centrioles, neurotubules, tubules in the tails of spermatozoa, the A-I band junction in myofibrils of striated muscle, and the ground substance between cisternae of endoplasmic reticulum in intestinal goblet cells also showed precipitate. In all cases, replacement of L-aspartic acid by D-aspartic acid in the medium resulted in unstained sections. The sensitivity of extramitochondrial sites to fixation, the need of ketoglutarate as an agent for protecting the enzymatic activity during the fixation process, and the known presence of only soluble isozyme in erythrocytes indicate that enzymatic activity at these sites can be attributed to the soluble isozyme. Localization of the soluble isozyme on the plasma membrane may be related to possible involvement in depolarization phenomena, amino acid transport, or synthesis of plasma membrane-bound mucopolysaccharides.
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PMID:The ultrastructural localization of the isozymes of aspartate aminotransferase in murine tissues. 553 35

The site of synthesis of the higher molecular weight precursor of mitochondrial aspartate aminotransferase (Sonderegger, P., Jaussi, R., and Christen, P. (1980) Biochem. Biophys. Res. Commun. 94, 1256-1260) has been determined by separation of free and membrane-bound polysomes under ionic conditions imitating the intracellular milieu and in vitro read-out translation of the two polysome fractions in a rabbit reticulocyte lysate. The amounts of the precursor of mitochondrial aspartate aminotransferase synthesized by free and membrane-bound polysomes were compared with the relative extent of the synthesized of cytosolic aspartate aminotransferase in the same fractions. Only a small (less than 10% of total) and for both isoenzymes quantitatively equivalent fraction was found to be produced by the membrane-bound polysome fraction; very likely, it has to be attributed to contaminating free polysomes. Apparently, the import of mitochondrial aspartate aminotransferase into the mitochondria does not involve an association of polysomes with intracellular membranes.
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PMID:Biosynthesis of aspartate aminotransferases. Both the higher molecular weight precursor of mitochondrial aspartate aminotransferase and the cytosolic isoenzyme are synthesized on free polysomes. 706 79

Little is known about the kinetics of most serum enzymes during the first hours of life, and even less about the effect on such enzyme activities of perinatal hypoxia-ischaemia. It was the aim of the present study to evaluate the serum kinetics of seven differently located cell enzymes in healthy and asphyxiated newborns during the 1st week of life. The serum activities of cytoplasmic and mitochondrial [aspartate aminotransferase (ASAT), creatine kinase (CK), glutamate dehydrogenase (GLDH), lactate dehydrogenase (LDH), and hydroxybutyrate dehydrogenase (HBDH)] and membrane-bound (gamma-glutamyl-transferase and leucine arylaminidase) enzymes were prospectively measured in full-term asphyxiated (n = 49) and healthy (n = 87) newborns during the first 144 h of life. The blood samples were taken serially at five fixed times: 0 (cord), 12, 24, 72, and 144 h postpartum. The asphyxiated newborns had significantly increased serum activities of ASAT, LDH, and HBDH up to 72 h postpartum, whereas healthy newborns showed higher CK and GLDH activities. Only the activities of ASAT, LDH, and HBDH seemed to depend on the oxygen supply of the fetus or newborn. If other causes of increased serum enzyme activities, e.g. liver diseases, haemolytic disorders, tumours, or inborn errors of metabolism, are excluded, elevated serum activities of ASAT, LDH, and HBDH should draw one's attention to a perinatal hypoxic-ischaemic insult of the newborn.
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PMID:Serum enzyme activities in full-term asphyxiated and healthy newborns: enzyme kinetics during the first 144 hours of life. 791 42

Soluble and membrane-bound aminopeptidase activities in 11 regions of the rat brain were assayed using L-Leucine-2-naphthylamide as a substrate. In addition, two metabolic enzymatic activities were compared: lactate dehydrogenase and aspartate aminotransferase. All enzymatic activities showed significant regional differences when the data were analyzed statistically. Soluble aminopeptidase and aspartate aminotransferase activities were significantly lower in cortical than in subcortical areas. Membrane-bound aminopeptidase activity levels were higher in cortical areas. Lactate dehydrogenase activities did not differ between cortical areas and the rest of the zones studied. However, although no wide regional differences were found for the other enzymatic activities, membrane-bound aminopeptidase varied markedly across brain regions: a fivefold difference was observed between zones such as parietotemporal cortex and medulla. The differential distribution of this enzymatic activity is consistent with the hypothesis that it could be responsible for the enzymatic inactivation of some neuroactive peptides.
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PMID:Regional distribution of soluble and membrane-bound aminopeptidase activities in rat brain. 849 Jul 37

The possible contribution of the mature portion of a mitochondrial precursor protein to its interaction with membrane lipids is unclear. To address this issue, we examined the interaction of the precursor to mitochondrial aspartate aminotransferase (pmAAT) and of a synthetic peptide corresponding to the 29-residue presequence peptide (mAAT-pp) with anionic phospholipid vesicles. The affinity of mAAT-pp and pmAAT for anionic vesicles is nearly identical. Results obtained by analyzing the effect of mAAT-pp or full-length pmAAT on either the permeability or microviscosity of the phospholipid vesicles are consistent with only a shallow insertion of the presequence peptide in the bilayer. Analysis of the quenching of Trp-17 fluorescence by brominated phospholipids reveals that this presequence residue inserts to a depth of approximately 9 A from the center of the bilayer. Furthermore, in membrane-bound pmAAT or mAAT-pp, both Arg-8 and Arg-28 are accessible to the solvent. These results suggest that the presequence segment lies close to the surface of the membrane and that the mature portion of the precursor protein has little effect on the affinity or mode of binding of the presequence to model membranes. In the presence of vesicles, mAAT-pp adopts considerable alpha-helical structure. Hydrolysis by trypsin after Arg-8 results in the dissociation of the remaining 21-residue C-terminal peptide fragment from the membrane bilayer, suggesting that the N-terminal portion of the presequence is essential for membrane binding. Based on these results, we propose that the presequence peptide may contain dual recognition elements for both the lipid and import receptor components of the mitochondrial membrane.
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PMID:Interaction of the precursor to mitochondrial aspartate aminotransferase and its presequence peptide with model membranes. 1093 77

Plastid stromules are membrane-bound protrusions of the plastid envelope that contain soluble stroma. Stromules are often found connecting plastids within a cell and fluorescence recovery after photobleaching (FRAP) experiments have demonstrated that green fluorescent protein (GFP) can move between plastids via these connections. In this report, the ability of endogenous plastid proteins to travel through stromules was investigated. The motility of GFP-labelled plastid aspartate aminotransferase and the Rubisco small subunit was studied in stromules by FRAP. Both fusion proteins assemble into protein complexes that appear to behave similarly to their endogenous counterparts. In addition, both enzymes are capable of trafficking between plastids via stromules.
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PMID:GFP-labelled Rubisco and aspartate aminotransferase are present in plastid stromules and traffic between plastids. 1475 18

One of the most intriguing phenomena observed during adriamycin (ADR) toxicity has been attributed to ADR-induced oxidative stress. The study was aimed to assess the protective effect of lipoic acid (LA) against ADR-induced damage to erythrocytes. Male albino rats (Wistar strain) were subjected to ADR (1 mg/kg body weight/day i.v.) once a week for a period of 12 weeks. Haematological indices like haemoglobin levels (Hb) and haematocrit (Ht) were also lowered along with a marked increase in the activities of serum glutamate pyruvate transaminase (SGPT) and serum glutamate oxaloacetate transaminase (SGOT). These rats demonstrated enhanced erythrocyte membrane lipid peroxidation (LPO) and an onslaught in the antioxidant defence armoury, witnessed by lowered activities of superoxide dismutase (SOD), glutathione peroxidase (GPx), vitamin A, vitamin C and vitamin E. Rats administered with ADR showed a marked decline in the activities of membrane-bound ATPases. Abnormal LPO and decreased deformability led to increased osmotic fragility of the red blood cells. Pretreatment with LA (35 mg/kg body weight/day i.p.) 24 hours prior to the administration of ADR once a week for a period of 12 weeks was effective in counteracting these biochemical disturbances, thereby minimizing the toxic side effects of ADR.
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PMID:Effect of lipoic acid on the oxidoreductive status of red blood cells in rats subject to oxidative stress by chronic administration of adriamycin. 1511 32


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