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)

Several biochemical and haematological abnormalities are associated with excessive alcohol intake and some are used in the recognition and management of alcoholics. The ideal biological marker for detecting and monitoring alcoholics should be sensitive and highly specific for alcohol abuse; its value should be affected by changes in alcohol intake over relatively short periods of time and it should be quick, simple, convenient and inexpensive to estimate. At the present time no simple reliable marker is available which fulfills these criteria. Measurements of serum aspartate transaminase, serum gamma-glutamyl-transpeptidase and mean corpuscular volume are of proven value however and the majority of alcoholics can be detected and monitored by combining the measurements of these three tests. Blood/breath alcohol measurements are of limited value for detection but are useful for follow up. Measurement of the plasma alpha-amino-n-butyric acid/leucine ratio is of disputed value and not likely to be of great practical use. Measurement of serum alpha-lipoproteins, erythrocyte delta-aminolaevulinic acid dehydrase activity and qualitative estimation of serum transferrin have all been proposed as markers for alcohol abuse and are currently under evaluation.
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PMID:Markers for detecting alcoholism and monitoring for continued abuse. 611 98

Of 33 components analyzed in overnight fasting serum from 30 patients with alcoholic liver cirrhosis, portal hypertension, and bleeding esophageal varices, total serum bile acids, gamma-glutamyltransferase, prealbumin, and tyrosine were the most frequently abnormal 'liver tests'. Total serum bile acids correlated significantly with bilirubin, immunoglobulin M, threonine, glycine, methionine, and tyrosine. Gamma-glutamyltransferase correlated with aspartate aminotransferase, glutamine, and alanine. Prealbumin correlated with albumin and immunoglobulins G and A. Tyrosine correlated with total bile acids, orosomucoid, and 10 amino acids. The amino acid ratio of valine + isoleucine + leucine to tyrosine + phenylalanine was lowered in all patients. It is concluded that the clinical picture and pattern of serum components in patients with alcoholic liver disease are influenced by many complex pathophysiological mechanisms.
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PMID:Total serum bile acids, gamma-glutamyl transferase, prealbumin, and tyrosine: sensitive serum markers of hepatic dysfunction in alcoholic liver cirrhosis. 614 23

Statistical analysis of variance was applied to data from determinations of 14 plasma constituents in 25 rats in order to evaluate the analytical, experimental and biological (inter-and intraindividual) component of variance. Blood was taken seven times in intervals of 8-10 days, the last one by catheter technique and the other by heart puncture. The analytical portion of variance was determined by the concurrent analysis of a pool plasma standard. The experimental component of variance was evaluated by the comparison of the variation of the catheter values with that of the pooled data from heart puncture. The coefficient of variation for the latter may be grouped into three categories: less than 10% for protein, Na+, K+, Ca2+; 10-20% for urea, phosphate and the enzymes as alanine aminotransferase, choline esterase, alkaline phosphatase and leucine arylamidase and 20-65% for the other enzymes lactate dehydrogenase, malate dehydrogenase, aspartate aminotransferase and creatine kinase. The results from the samples taken by catheter technique generally revealed the lower values for the mean as well as for the variance. It became evident that the procedure of heart puncture is afflicted with the most aggravating interference factors, thus accounting for most of the experimental component of variance. The observed differences between the single blood drawings, the non-Gaussian distribution for several constituents, and the interactions between the components of variance do not always fit for the statistical concept of additivity of the single components.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Biological, analytical and experimental components of variance in a long-term study of plasma constituents in rat. 660 70

The precursor of mitochondrial aspartate aminotransferase from pig heart was synthesized in vitro, purified by immunoprecipitation and partially sequenced. The precursor is 24 amino acid residues longer than the mature protein. Methionine, leucine and isoleucine positions on the peptide extension were assigned.
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PMID:The precursor of mitochondrial pig heart aspartate aminotransferase: preliminary sequence data. 667 33

Stimulation of mitochondrial aspartate aminotransferase (mAAT) activity by testosterone was determined in organ cultures of rat ventral prostate. The effect of testosterone on citrate accumulation in the culture medium was also determined. Testosterone stimulation of citrate accumulation and mAAT occurred in a dose dependent manner. Stimulation of mAAT activity occurred after a 1-3 h lag period and appeared to involve the synthesis of specific RNA since the response was inhibited by actinomycin D. Studies utilizing [3H]L-leucine indicated that unlike the total tissue, testosterone stimulated the incorporation of [3H]leucine into proteins of the mitochondrial fraction. The results suggested that mitochondrial proteins may be more sensitive to testosterone stimulation than cytosol proteins. The response was specific for mAAT since testosterone had no effect on mitochondrial malic dehydrogenase activity. The data suggested that testosterone may regulate prostate citrate content by the induction of mAAT in prostate mitochondria, which results in a source oxalacetic acid for citrate synthesis through transamination of aspartate by alpha ketoglutarate.
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PMID:Testosterone stimulation of mitochondrial aspartate aminotransferase in organ cultures of rat ventral prostate. 670 48

L-Leucine and its nonmetabolized analogue, 2-aminobicyclo-[2,2,1]heptane-2-carboxylic acid (BCH) activate glutamate dehydrogenase in pancreatic islets, whether the reaction velocity is measured in the direction of glutamate synthesis or glutamate deamination. The rate of glutamate oxidative deamination is increased by ADP and inhibited by 2-ketoglutarate, NH4+ and GTP. The islet homogenate catalyzes the transamination between L-glutamate and either 2-ketoisocaproate or pyruvate, and between 2-ketoglutarate and L-leucine, L-aspartate, L-alanine, L-isoleucine, L-valine, L-norvaline or L-norleucine, but not b (+/-) BCH. The glutamate-aspartate transaminase is preferentially located in mitochondria relative to other transaminases. The parallel effects of L-leucine and BCH on glutamate dehydrogenase and their vastly different abilities to act as transamination partners may account for both analogies and discrepancies in the metabolic and functional responses of the islets to these two branched-chain amino acids.
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PMID:The stimulus-secretion coupling of amino acid-induced insulin release. XI. Kinetics of deamination and transamination reactions. 675 75

Normal serum concentrations of methionine, leucine, isoleucine and valine have been found in 10 anaesthetists using nitrous oxide under their regular working conditions without scavenging of patients' exhaled gas. Mean inhaled concentrations of nitrous oxide ranged from 150 to 400 p.p.m. The results indicate either that there was no significant inhibition of methionine synthase (attributable to oxidation of vitamin B12 by nitrous oxide) or that methionine concentrations were maintained by dietary intake or by the alternative betaine pathway of methylation of homocysteine. In either case, anaesthetists working under these conditions should not be at risk from reduced methionine concentrations. We also report normal serum activities of aspartate transaminase and gamma glutamyl transpeptidase.
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PMID:Serum methionine and hepatic enzyme activity in anaesthetists exposed to nitrous oxide. 708 22

The apoenzyme form of cytosolic aspartate aminotransferase of pig hearts was allowed to react at room temperature with 1 equiv of pyridoxal 5'-sulfate. The resulting covalently modified enzyme was degraded with pepsin. Fluorescent tri-, tetra-, and hexapeptides were isolated and characterized as fragments of the active site sequence: Phe-Ser-Lys-Asn-Phe-Gly-Leu. This sequence contains a modified form (Lys) of lysine-258 that is known to form a Schiff base with pyridoxal phosphate in the active site. The peptides were further degraded by acid hydrolysis to give a fluorescent derivative of lysine with light absorption and chemical properties similar to those of the original modified enzyme. A related series of peptides were obtained from apoenzyme after reaction with the 5-carboxyethenyl analogue of pyridoxal 5'-phosphate.
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PMID:Covalently modified peptides isolated from aspartate aminotransferase after reaction with pyridoxal 5'-sulfate. 717 51

The rates of synthesis of aspartate aminotransferase isozymes in the liver and skeletal muscle in pyridoxine-deficient rats were examined. The rates of synthesis were compared in rats given pyridoxine-deficient diet ad libitum, rats given control diet ad libitum and rats pair-fed with those on the deficient diet. The rates of incorporation of 3H-L-leucine by both cytosolic and mitochondrial enzymes were highest in pair-fed controls. Incorporation of radioactivity into the cytosolic enzyme was higher in deficient rat liver than in that of controls fed ad libitum, but the rate of incorporation into the mitochondrial enzyme was similar in these two groups. In muscle the rates of incorporation of labeled leucine into both isozymes were similar in all groups when expressed relative to total protein synthesis. It was suggested that increase of glucocorticoid receptor might result in increased synthesis of cytosolic aspartate aminotransferase in pyridoxine-deficient rat liver.
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PMID:Effect of pyridoxine-deficiency on the syntheses of aspartate aminotransferase in rat liver and muscle in vivo. 717 38

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


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