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:2.6.1.2 (alanine aminotransferase)
26,722 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of endurance training (running 90 min/day, 30 m/min, approximately 10% grade) on hepatic gluconeogenesis were studied in 24-h-fasted rats by using the isolated liver perfusion technique. After isolation, livers were perfused (single pass) for 30 min with Krebs-Henseleit bicarbonate buffer and fresh bovine red blood cells (hematocrit 20-24%) with no added substrate. Alanine (10 mM), dihydroxyacetone (20 mM), or glutamine (10 mM) was then added to the reservoir, and perfusions continued for 60 min. No significant differences were observed in perfusate pH, hematocrit, bile production, or serum alanine aminotransferase effluxing from livers from trained or control animals for any perfusion. Livers from trained animals that were perfused with 10 mM alanine demonstrated significantly higher rates of glucose production compared with livers from control animals (0.51 +/- 0.04 vs. 0.40 +/- 0.02 micromol.min-1.g liver-1, respectively). Elevations of a similar magnitude were observed for rates of [14C]alanine incorporation into [14C]glucose in livers from trained vs. control animals (8,797 +/- 728 vs. 6,962 +/- 649 dpm.min-1.g liver-1, respectively). Significant increases were also observed in hepatic alanine uptake (30%), oxygen consumption (23%), urea release (22%), and 14CO2 production (29%) of livers of endurance-trained animals. In contrast, no significant differences between groups were observed for hepatic glucose output after perfusions with either dihydroxyacetone (1.75 +/- 0.06 micromol.min-1.g liver-1) or glutamine (0.62 +/- 0.04 micromol.min-1.g liver-1). Further, during perfusions with dihydroxyacetone and glutamine, training had no significant impact on precursor uptake, oxygen consumption, or urea output. The current findings indicate a training-induced adaptation for hepatic gluconeogenesis located below the level of the triose phosphates.
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PMID:Enhanced hepatic gluconeogenic capacity for selected precursors after endurance training. 884 48

Transamination reaction is the first step in the catabolism of most of the L-amino acids. Alanine is an important molecule in the inter-organ nitrogen transport, conveying them from muscle to the liver. Amino groups from this amino acid are generally first transferred to alpha-ketoglutarate in the cytosol of liver cells to form glutamate and leaving behind the corresponding alpha-keto acid analog. Measurements of the alanine aminotransferase (EC2.6.1.2.) activity were compared in liver, mammary gland and skeletal muscle in virgin, lactating and weaning dam rats. In this study liver was the principal tissue involved in alanine transamination, while muscle showed a reduction in the enzyme activity during lactation. Results indicate an increase in alanine amino-transferase activity in the mammary gland during lactation and weaning when compared with virgin rats. This suggests that mammary gland during lactation is an important extra-hepatic tissue involved in the metabolism of alanine and probably shunted into the pathways for amino group metabolism in terms of nitrogen economy.
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PMID:Alanine aminotransferase activity in mammary tissue, muscle and liver of dam rat during lactation and weaning. 898 75

The idea of a metabolic coupling between neurons and astrocytes in the brain has been entertained for about 100 years. The use recently of simple and well-compartmentalized nervous systems, such as the honeybee retina or purified preparations of neurons and glia, provided strong support for a nutritive function of glial cells: glial cells transform glucose to a fuel substrate taken up and used by neurons. Particularly, in the honeybee retina, photoreceptor-neurons consume alanine supplied by glial cells and exogenous proline. NH4+ and glutamate are transported into glia by functional plasma membrane transport systems. During increased activity a transient rise in the intraglial concentration of NH4+ or of glutamate causes a net increase in the level of reduced nicotinamide adenine dinucleotides [NAD(P)H]. Quantitative biochemistry showed that this is due to activation of glycolysis in glial cells by the direct action of NH4+ and of glutamate, probably on the enzymatic reactions controlled by phosphofructokinase alanine aminotransferase and glutamate dehydrogenase. This activation leads to a massive increase in the production and release of alanine by glia. This constitutes an intracellular signal and it depends upon the rate of conversion of NH4+ and of glutamate to alanine and alpha-ketoglutarate, respectively, in the glial cells. Alanine and alpha-ketoglutarate are released extracellularly and then taken up by neurons where they contribute to the maintenance of the mitochondrial redox potential. This signaling raises the novel hypothesis of a tight regulation of the nutritive function of glia.
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PMID:The nutritive function of glia is regulated by signals released by neurons. 929 50

Although glutamine is a major carbon source for mammalian cells in culture, its chemical decomposition or cellular metabolism leads to an undesirable excess of ammonia. This limits the shelf-life of glutamine-supplemented media and may reduce the cell yield under certain conditions. We have attempted to develop a less ammoniagenic medium for the growth of BHK-21 cells by a mole-to-mole substitution of glutamine by glutamate. This results in a medium that is thermally stable but unable to support an equivalent growth yield. However, supplementation of the glutamate-based medium with asparagine (3 mM) and a minimal level of glutamine (0.5 mM) restored the original growth capacity of the cultures. Substitution of the low level of glutamine with the glutamine dipeptides, ala-gln (1 mM), or gly-gln (3 mM) resulted in an equivalent cell yield and in a thermally stable medium. The ammonia accumulation in cultures with glutamate-based medium was reduced significantly (>60%). Factors mediating growth and adaptation in medium substituted with glutamate were also investigated. The maximum growth capacity of the BHK-21 cells in glutamate-based medium (without glutamine) was achieved after a period of adaptation of 5 culture passages from growth in glutamine-based cultures. Adaptation was not influenced by increases in glutamate uptake which was constitutively high in BHK cells. Adaptation was associated with changes in the activities of enzymes involved in glutamate or glutamine metabolism. The activities of glutamine synthetase (GS) and alanine aminotransferase (ALT) increased significantly and the activity of phosphate-activated glutaminase (PAG) decreased significantly. The activity of glutamate dehydrogenase (GDH) showed no significant change after adaptation to glutamate. These changes resulted in an altered metabolic profile which included a reduced ammonia production but an increased alanine production. Alanine production is suspected of being an alternative route for removal of excess nitrogen.
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PMID:The adaptation of BHK cells to a non-ammoniagenic glutamate-based culture medium. 1039 67

The effect of prolonged treatment with the standardized Panax ginseng extract G115 on the antioxidant capacity of the liver was investigated. For this purpose, rats that had received G115 orally at different doses for 3 months and untreated control rats were subjected to exhaustive exercise on a treadmill. A bell-shaped dose response on running time was obtained. The results showed that the administration of G115 significantly increases the hepatic glutathione peroxidase activity (GPX) and the reduced glutathione (GSH) levels in the liver, with a dose-dependent reduction of the thiobarbituric acid reactant substances (TBARS). After the exercise, there is reduced hepatic lipid peroxidation, as evidenced by the TBARS levels in both the controls and the treated animals. The GPX (glutathione peroxidase) and SOD (superoxide dismutase) activity are also significantly increased in the groups receiving G115, compared with the controls. The hepatic transaminase levels, ALT (Alanine-amino-transferase) and AST (Aspartate-amino-transferase), in the recuperation phase 48 h after the exercise, indicate a clear hepatoprotective effect related to the administration of the standardized Panax ginseng extract G115. At hepatic level, G115 increases the antioxidant capacity, with a marked reduction of the effects of the oxidative stress induced by the exhaustive exercise.
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PMID:Effects of administration of the standardized Panax ginseng extract G115 on hepatic antioxidant function after exhaustive exercise. 1044 26

This paper is the seventh in a series dealing with reference procedures for the measurement of catalytic activity concentrations of enzymes at 37 degrees C and the certification of reference preparations. Other parts deal with: Part 1. The Concept of Reference Procedures for the Measurement of Catalytic Activity Concentrations of Enzymes; Part 2. Reference Procedure for the Measurement of Catalytic Concentration of Creatine Kinase; Part 3. Reference Procedure for the Measurement of Catalytic Concentration of Lactate Dehydrogenase; Part 4. Reference Procedure for the Measurement of Catalytic Concentration of Alanine Aminotransferase; Part 5. Reference Procedure for the Measurement of Catalytic Concentration of Aspartate Aminotransferase; Part 6. Reference Procedure for the Measurement of Catalytic Concentration of Gamma-Glutamyltransferase. A document describing the determination of preliminary reference values is also in preparation. The certification of the catalytic activity concentrations as determined by the recently elaborated IFCC primary reference methods at 37 degrees C of four enzyme preparations, namely IRMM/IFCC 452 (gamma-glutamyltransferase), IRMM/IFCC 453 (lactate dehydrogenase 1), IRMM/IFCC 454 (alanine aminotransferase) and IRMM/IFCC 455 (creatine kinase) is described. Homogeneity data were derived from previous results. Stability was assessed using recently obtained data as well as data from previous stability studies. The collaborative study for value assignment was performed under a strict quality control scheme to ensure traceability to the primary reference method. Uncertainty of the materials was assessed in compliance with the Guide to the Expression of Uncertainty in Measurement. The certified values obtained at 37 degrees C are 1.90 microkat/l +/- 0.04 microkat/l (114.1 U/l +/- 2.4 U/l), for gamma-glutamyltransferase, 8.37 microkat/l +/- 0.12 microkat/l (502 U/l +/- 7 U/l), for lactate dehydrogenase 1, 3.09 microkat/l +/- 0.07 microkat/l (186 U/l +/- 4 U/l), for alanine aminotransferase and 1.68 microkat/l +/- 0.07 microkat/l (101 U/l +/- 4 U/l), for creatine kinase. The materials are intended for internal quality control as well as for the evaluation of test systems as required by recent European Union legislation. Furthermore, the materials can be used to transfer accuracy from a reference method to a routine procedure provided the procedures exhibit the same analytical specificity and the certified materials are commutable.
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PMID:IFCC primary reference procedures for the measurement of catalytic activity concentrations of enzymes at 37 degrees C. International Federation of Clinical Chemistry and Laboratory Medicine. Part 7. Certification of four reference materials for the determination of enzymatic activity of gamma-glutamyltransferase, lactate dehydrogenase, alanine aminotransferase and creatine kinase accord. 1224 Oct 24

This study sought to investigate the ameliorating effects of soy 11S protein on the impacts of alcohol consumption in rat hepatocytes and in reducing total cholesterol levels and total lipid levels in the serum. Liver histology and the clinically important enzyme markers (Aspartate Aminotransferase: AST and Alanine Aminotransferase: ALT) of rats, administered with both alcohol and soy 11S protein treatments, were compared with those in the control group. The treatment regimen (11S soy protein extract) significantly reduced serum ALT and AST levels, indicating the hepato-protective effects of soy 11S protein. Furthermore, total cholesterol and total lipid levels were significantly reduced. In addition to preventing the presence of lipid droplets and secondary lysosomes, electron microscopy indicated that the administration of the soy 11S protein treatment preserved important hepatocyte structures. These results indicate that soy 11S protein can positively mediate the effects of alcohol on hepatocytes and general liver functions.
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PMID:Ameliorative effects of soy 11S protein on liver damage and hyperlipidemia in alcohol-fed rats. 1546 10

Fatty liver at ultrasounds, with/ without raised plasma levels of hepatic enzymes, is common in obesity. In most cases, it is the hallmark of non-alcoholic fatty liver disease (NAFLD), a potentially progressive disease associated with insulin resistance and the metabolic syndrome (MS). We tested the hypothesis that insulin resistance per se might be associated with hepatocellular necrosis. Alanine and aspartate aminotransferases (ALT and AST; no.=799) and gamma-glutamyltranspeptidase (GGT; no.=459) were analyzed in a group of treatment-seeking obese patients recruited in 12 Italian medical centers. Insulin resistance was calculated by the homeostasis model assessment method (HOMA-IR; no.=522). Median ALT and AST increased with increasing obesity class (p=0.001 and p=0.005) and exceeded normal limits in 21.0% of cases. Also HOMA-IR increased with the obesity class (p<0.0001), and was higher in subjects with elevated ALT (median, 4.93 vs 2.89; p<0.0001). A significant correlation was observed between HOMA-IR and ALT (R2=0.208; p<0.0001), as well as between HOMA-IR and AST or GGT (R2=0.112 and R2=0.080; p<0.0001). The correlation was maintained when cases with elevated enzyme levels were omitted from analysis. Diabetes and hypertriglyceridemia were the features of the MS most commonly associated with raised liver enzymes. In logistic regression, after correction for age, gender, BMI and features of the MS, HOMA-IR maintained a highly predictive value for raised ALT, AST and GGT. We conclude that in obesity insulin resistance is a risk factor for raised liver enzyme levels, possibly related to NAFLD.
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PMID:Aminotransferase and gamma-glutamyltranspeptidase levels in obesity are associated with insulin resistance and the metabolic syndrome. 1596 6

Alanine is the most effective precursor for gluconeogenesis among amino acids, and the initial reaction is catalyzed by alanine aminotransferase (AlaAT). Although the enzyme activity increases during fasting, this effect has not been studied extensively. The present study describes the purification and characterization of an isoform of AlaAT from rat liver under fasting. The molecular mass of the enzyme is 17.7 kD with an isoelectric point of 4.2; glutamine is the N-terminal residue. The enzyme showed narrow substrate specificity for L-alanine with Km values for alanine of 0.51 mM and for 2-oxoglutarate of 0.12 mM. The enzyme is a glycoprotein. Spectroscopic and inhibition studies showed that pyridoxal phosphate (PLP) and free -SH groups are involved in the enzymatic catalysis. PLP activated the enzyme with a Km of 0.057 mM.
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PMID:A novel low molecular weight alanine aminotransferase from fasted rat liver. 2116 50

Soybean (Glycine max [L.] Merr) leaves contain a low level (0.05 micromole per gram fresh weight) of gamma-aminobutyric acid (Gaba) but the concentration of this non-protein amino acid increased to 1 to 2 micromoles per gram fresh weight within 5 minutes after transfer of plants or detached leaves from 33 degrees C to 22 degrees C or lower temperatures. A parallel decrease occurred in the concentration of glutamate. Accumulation of Gaba was also triggered by mechanical damage to the soybean leaves, but in plants subjected to a gradual reduction in temperature (2 degrees C per minute) only a small increase in Gaba occurred. A rapid increase in the concentration of alanine and decrease in glycine occurred upon transfer of the soybean plants to darkness and was not influenced by temperature. When plants were returned to normal growing conditions, all changes in amino acid concentrations were fully reversed in 1 hour.In soybean leaf discs incubated with [(14)C]glutamate, a rapid accumulation of [(14)C]Gaba was detected, and glutamate decarboxylase activity of the soybean leaf considerably exceeded (>30-fold) that of Gaba pyruvate transaminase. Part of the transaminase was localized in the mitochondria, but glutamate decarboxylase was not associated with any organelle or membrane component of the leaf cell. We consider that Gaba accumulation results from some change in intracellular compartmentation of the cell triggered by low temperature shock or mechanical damage. The accumulation of alanine due to a light-dark transition could be accounted for by transamination. [(14)C]Alanine formation was demonstrated when soybean leaf extracts were incubated with glutamate, aspartate, or serine and [(14)C]pyruvate.The changes in amino acid concentrations described for soybean leaves were demonstrated for all the vegetative tissues of the soybean plant and at variable rates in the leaves of a range of plant species. The response in detached tomato (Lycopersicon esculentum Mill.) leaves was of a similar magnitude to soybean. Thus, precautions are necessary to minimize changes in amino acid composition induced by manipulation and extraction of plant material.
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PMID:Rapid Accumulation of gamma-Aminobutyric Acid and Alanine in Soybean Leaves in Response to an Abrupt Transfer to Lower Temperature, Darkness, or Mechanical Manipulation. 1666 65


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