Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.6.1.2 (alanine aminotransferase)
 26,722 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In previous studies it was found that: (a) aspartate aminotransferase increases the aspartate dehydrogenase activity of glutamate dehydrogenase; (b) the pyridoxamine-P form of this aminotransferase can form an enzyme-enzyme complex with glutamate dehydrogenase; and (c) the pyridoxamine-P form can be dehydrogenated to the pyridoxal-P form by glutamate dehydrogenase. It was therefore concluded (Fahien, L.A., and Smith, S.E. (1974) J. Biol. Chem 249, 2696-2703) that in the aspartate dehydrogenase reaction, aspartate converts the aminotransferase into the pyridoxamine-P form which is then dehydrogenated by glutamate dehydrogenase. The present results support this mechanism and essentially exclude the possibility that aspartate actually reacts with glutamate dehydrogenase and the aminotransferase is an allosteric activator. Indeed, it was found that aspartate is actually an activator of the reaction between glutamate dehydrogenase and the pyridoxamine-P form of the aminotransferase. Aspartate also markedly activated the alanine dehydrogenase reaction catalyzed by glutamate dehydrogenase plus alanine aminotransferase and the ornithine dehydrogenase reaction catalyzed by ornithine aminotransferase plus glutamate dehydrogenase. In these latter two reactions, there is no significant conversion of aspartate to oxalecetate and other compounds tested (including oxalacetate) would not substitute for aspartate. Thus aspartate is apparently bound to glutamate dehydrogenase and this increases the reactivity of this enzyme with the pyridoxamine-P form of aminotransferases. This could be of physiological importance because aspartate enables the aspartate and ornithine dehydrogenase reactions to be catalyzed almost as rapidly by complexes between glutamate dehydrogenase and the appropriate mitochondrial aminotransferase in the absence of alpha-ketoglutarate as they are in the presence of this substrate. Furthermore, in the presence of aspartate, alpha-ketoglutarate can have little or no affect on these reactions. Consequently, in the mitochondria of some organs these reactions could be catalyzed exclusively by enzyme-enzyme complexes even in the presence of alpha-ketoglutarate. Rat liver glutamate dehydrogenase is essentially as active as thebovine liver enzyme with aminotransferases. Since the rat liver enzyme does not polymerize, this unambiguously demonstrates that monomeric forms of glutamate dehydrogenase can react with aminotransferases.
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PMID:Effect of aspartate on complexes between glutamate dehydrogenase and various aminotransferases. 1 47

The quantitative differences between the activity of the 3 common phenotypes of human red cell GPT has been confirmed. In addition, the activity of red cell GPT 1 was found to be greater in young children than in adults. No such difference was found for the GPT 2 phenotype. The activity of the red cell GPT 1 was found to decrease with age, reaching the adult level at the age of 10 to 12 years. Red cell GPT of all the 3 common phenotypes in both adults and children was found to show a similar response to the addition of excess pyridoxal phosphate. A method has been devised for the partial purification of human GPT (cytoplasmic) from liver. GPT 1 and GPT 2 have been purified, and very few significant differences were found amongst the physical and kinetic parameters tested.
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PMID:Comparative studies on the human glutamate-pyruvate transaminase phenotypes--GPT 1, GPT 2-1, GPT 2. 24 1

Coenzymes participate in many of the enzyme analyses performed in the clinical laboratory. Supplementation of assay systems with optimal levels of coenzymes has recently been recommended as part of efforts to achieve interlaboratory standardization of enzyme measurements. Aspartate aminotransferase and alanine aminotransferase require pyridoxal phosphate for expression of enzyme activity. The role of this coenzyme in enzymatic transamination and the effects of its supplementation on the clinical estimation of these two enzymes is reviewed. Other coenzymes discussed are flavins, coenzymes for glutathione reductase, glucose oxidase, cholesterol oxidase and diaphorase, as well as thiamine pyrophosphate, coenzyme for transketolase. Catalase and peroxidase are used as examples of hemoproteins utilized in clinical measurements. Two peptide coenzymes, colipase and glutathione, are also considered. Measurement of apoenzyme stimulation upon supplementation with specific coenzymes is discussed as a valuable technique for quantitative coenzyme measurements or assessment of vitamin nutritional status.
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PMID:Review: the role of coenzymes in clinical enzymology. 33 88

D-Vinylglycine (2-amino-3-butenoate) functions as a transamination substrate and irreversible inactivator of the homogeneous pyridoxal phosphate-dependent D-amino acid transaminases from Bacillus subtilis and Bacillus sphaericus. In the absence of alpha-ketoglutarate as co-substrate, vinyl-glycine causes little if any inactivation of either enzyme; in the presence of excess alpha-ketoglutarate, both enzymes are inactivated with pseudo-first order kinetics. The limiting rate constant for inactivation of the B. sphaericus enzyme is 1.9 min-1, for the B. subilis enzyme it is 0.36 min-1. The number of catalytic events before inactivation is about 450 for the B. sphaericus enzyme and about 800 for the B. subtilis enzyme; that is, about 0.2% inactivation in each catalytic cycle for the former enzyme and 0.15% for the latter. Comparisons are made with the L-aspartate amino-transferase from pig heart which is inactivated completely in one catalytic cycle and the L-alanine aminotransferase which is not inactivated in many cycles. Comparisons are also made between the likely mode of D-transaminase inactivation produced by vinylglycine and the mode of inactivation induced by beta-chloro-D-alanine.
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PMID:Inactivation of bacterial D-amino acid transaminases by the olefinic amino acid D-vinylglycine. 40 67

Nutritional status of vitamin B6 was investigated in two groups of 102 hospitalized aged. Vitamin B6 intake was estimated. Erythrocyte glutamic-pyruvic transaminase stimulation in vitro with pyridoxal phosphate and SGOT were studied as the biochemical criteria of vitamin B6 status: 18.6% of the subjects consumed less than 0.66 mg of vitamin B6 per day; 28.4% showed a percentage stimulation in vitro with pyridoxal phosphate of more than 15%. There was no significant correlation between basal erythrocyte glutamic-pyruvic transaminase activity and dietary protein, dietary vitamin B6 dietary vitamin B6/100 g of protein, SGOT, hemoglobin, mean corpuscular volume, and iron. All the biochemical parameters used for evaluating vitamin B6 status appeared higher in females, but no statistical difference between male and female groups was noted. Only SGOT levels of female subjects reflected their vitamin B6 status. A large individual variation of vitamin B6 requirement was indicated in both groups studied. Supplements with 2.5 mg of vitamin B6 to deficient subjects caused an increase in transaminase levels, though females showed a higher response. A higher recommended allowance of vitamin B6 for the aged male and female subjects was considered desirable.
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PMID:Vitamin B6 status of the hospitalized aged. 67 75

1. Diets containing graded levels of pyridoxine hydrochloride (to supply 0.26--30 mg pyridoxine/kg) were given to seven duplicate groups of turbot (Scophthalmus maximus) for 12 weeks and their growth rate was measured during this period. 2. Good growth was obtained on all treatments except those groups given less than 1.0 mg pyridoxine/kg diet. These fish grew normally until weeks 8--10 but thereafter their weight gain was significantly less than that for other treatments. 3. Measurements of aspartate aminotransferase (EC 2.6.1.1) in muscle and liver and of alanine amino-transferase (EC 2.6.1.2) in liver of the turbot showed that the activities of these enzymes increased with increasing dietary pyridoxine intake up to a level of 2.5 mg pyridoxine/kg. The activities of these enzymes were not further enhanced by additional dietary pyridoxine. 4. Percentage stimulation of these enzymes by pre-incubation of extracts with pyridoxal phosphate was minimal with those groups of turbot given 2.5 mg pyridoxine/kg diet or more. 5. It is concluded that the dietary requirement of turbot for vitamin B6 can be safely met with a diet containing between 1.0 and 2.5 mg pyridoxine/kg. 6. An eighth group of turbot given the pyridoxine antagonist 4-deoxypyridoxine hydrochloride (20 mg/kg) showed retarded growth after 2 weeks, together with a high mortality rate.
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PMID:Studies on the nutrition of marine flatfish. The pyridoxine requirement of turbot (Scophthalmus maximus). 69 64

Alanine aminotransferase activity in serum increases significantly when serum is incubated with pyridoxal phosphate. The increase depends on the L-alanine concentration in the final assay mixture, being greatest at 800 mmol/liter. Preincubation of 22 normal sera, in a 10:1 ratio with an 8.09 mmol/liter pyridoxal phosphate solution, resulted in an increase in the alanine aminotransferase activity from 10.5 +/- 4.9 U/liter (mean +/- SD) to 28.4 +/- 5.3 U/liter, an increase of 170%. The absolute amount of apoalanine aminotransferase is relatively constant over a wide range of enzyme activities.
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PMID:Activation of alanine aminotransferase in serum by pyridoxal phosphate. 83 80

Effects of pregnancy superimposed upon a rapid phase of growth in the rat on the vitamin B-6 needs during gestation were examined. Rats were fed 1.2, 2.4, 4.8, 9.6, or 19.2 mg pyridoxine-HCl/kg diet from weaning. Some animals from each dietary treatment were mated at 55 (P-55) and 115 (P-115) days of age; others of the same ages served as nonpregnant controls. Analyses were made on day 21 of gestation. Excepting the 1.2-mg diet treatment, maternal weight gains during gestation were greater for P-55 groups compared with gains of the P-115 groups, possibly reflecting maternal growth. Both maternal weight gains and fetal weights were less for the 1.2-mg, P-55 group; otherwise reproductive performance was similar among the groups. On the basis of stimulation of erythrocyte alanine aminotransferase activity by pyridoxal phosphate added in vitro, the needs in all pregnant and nonpregnant groups were met by 2.4 mg pyridoxine/kg diet. However, on the basis of vitamin B-6 saturation of tissues, the pyridoxine needs were 9.6 mg/kg diet for young growing animals and 4.8 mg/kg diet for older animals in which growth had almost ceased. The needs for both young and older pregnant animals possibly exceeded 19.2 mg pyridoxine/kg diet for vitamin B-6 saturation of maternal liver, fetus, and fetal brain. Pregnancy superimposed upon a rapid phase of growth in conjunction with a restricted intake of pyridoxine resulted in low values for most parameters used in the assessments compared with values for animals fed the same vitamin level but mated after growth velocity had diminished.
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PMID:Effects of different levels of pyridoxine fed during pregnancy superimposed upon growth in the rat. 112 71

The influence of different levels of dietary pyridoxine-HC1 (1.2, 2.4, 4.8, 9.6, 19.2, 38.4, 76.8 and 153.6 mg/kg diet) fed to dams on certain parameters of developing and mature brain was studied in rats. Brain weights and alanine aminotransferase (ALAT) activities (initial and following in vitro addition of pyridoxal phosphate, PLP) were significantly reduced in brains of 12-day-old pups of dams fed the lowest level of pyridoxine compared to other treatments; in vitro addition of PLP significantly stimulated the activities of glutamic acid decarboxylase (GAD) and ALAT. Vitamin B-6 concentrations in brain were higher for 2-day-old pups of dams fed 38.4 or 76.8 mg vitamin/kg diet and for 12-day-old pups of dams fed 2.4 to 153.6 mg compared to the 1.2 mg groups; at weaning, values were greater in groups fed 76.8 or 153.6 mg compared to the 1.2 mg group. As brain developed during the suckling period, the content of bitamin B-6 and protein increased in all groups, except the 1.2 mg group in which values remained the same. The vitamin and protein content in brain had not reached chemical maturity at weaning as evidenced by greater concentrations of each in brains of dams as compared with values for 21-day-old progeny. As brain developed, ALAT activity increased about 30 times from age 2 to 21 days when activities were similar to those observed in mature brains of dams. Activity of GAD in brain increased about four times from age 12 to 21 days.
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PMID:Influence of different levels of dietary pyridoxine on certain parameters of developing and mature brains in rats. 126 75

The erythrocyte alanine aminotransferase (E-ALAT) activity with and without in vitro stimulation by pyridoxal phosphate of 60 healthy adolescents was measured before and after 6 weeks of supplementation with different water-soluble vitamins. The subjects who were divided into six groups received placebo (lactose tablets), pyridoxine, pyridoxine + ascorbic acid, pyridoxine + iron, pyridoxine + riboflavin and multivitamin supplements, respectively. Presupplementation E-ALAT activity increased significantly (p less than 0.05) for all supplemented subjects after 6 weeks. Deficient subjects (E-ALAT) index less than 1.16) however failed to respond to a combination of pyridoxine + ascorbic acid or multivitamins. It is suggested that pyridoxine in multivitamin preparations must exceed 1 mg to produce any useful improvement in vitamin B6 status of adolescents on suboptimal vitamin B6 intakes.
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PMID:Effect of supplementation with water-soluble vitamins on erythrocyte alanine aminotransferase activity of healthy adolescents. 187 96


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