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)

A chromatographic-videodensitometric assay was found to be appropriate for measuring the activity of glutamate dehydrogenase, aspartate aminotransferase, alanine aminotransferase, ornithine-2-oxoacid aminotransferase and histidine ammonia-lyase in human tissue homogenates. From the assay mixtures containing substrate(s), cofactor(s), buffer and tissue extract, five or ten microliters samples were taken at different time intervals and chromatographed on Dowex 50 X 8 type resin-coated chromatosheets. On each chromatoplate 50 nmoles of the amino acid to be measured were separately run as a reference for videodensitometric evaluation. By comparing the density of the reference amino acid to that of the individual samples the molar amount of amino acids formed or consumed in the reaction could be calculated. The present findings suggest that the chromatographic-videodensitometric microassay (CV-technique) is suitable for measuring the activity of amino acid transforming enzymes in minute amounts of tissue extracts.
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PMID:Determination of enzyme activity by chromatography and videodensitometry. I. Microassay of amino acid transforming enzymes in human tissue homogenates. 54 67

Gyrocotyle fimbriata isolated from the spiral valve of Hydrolagus colliei were washed, then held in a filtered seawater-penicillin-Tris buffer medium. Ammonia and urea release to the medium declined together and ammonia production was minimal when the urea concentration was below detectable limits. Alanine and smaller amounts of glycine were released to the medium at a more constant rate. After 12 hr the alanine-glycine excretion was more than 20 times the ammonia excretion. L-arginine, L-serine, L-histidine, and urea were most effective in stimulating ammonia production by whole worms; other L-amino acids were essentially ineffective. L-glutamate dehydrogenase, L-amino acid oxidase, uricase, and ornithine transcarbamylase were below detectable levels. L-serine dehydrase, L-arginase, L-histidase, and urease were detected in tissue homogenates and probably account for most of the endogenous ammonia production. L-arginase has a molecular weight of 28,000 by Sehpadex gel filtration. The high levels of glutamate-pyruvate transaminase and lower levels of glutamate-oxalacetate transaminase correlate with the high level of alanine excretion. It is concluded that (1) ammonia production is not strongly linked to the overall energy metabolism of Gyrocotyle and is probably a result of a series of unrelated enzymatic reactions such as the action of urease of urea from the tissue of the rat fish, and (2) alanine and glycine are the major nitrogen excretory products and their production is linked to the energy metabolism of Gyrocotyle.
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PMID:Ammonia formation and amino acid excretion by Gyrocotyle fimbriata (Cestoidea). 111 78

A comparative study of the hepatoprotective effect of carnosine and 4-methyluracil under CCl4-induced acute toxic hepatitis has been carried out. The extent of liver injury and its regeneration were established from morphological data as well as from changes in the activities of alanine aminotransferase (ALT) and histidase and the bilirubin content in blood serum. Hyperlipoperoxidation in the liver and serum was assessed by the amount of TBA-active products. It was found that by day 10 of experimental hepatitis ALT and histidase levels in blood sera of untreated animals exceeded the normal values 1.3- and 3.9-fold, whereas those in the carnosine-treated group approximated the values characteristic of intact animals. The activity of serum ALT in animals treated with vitamin B12 or 4-methyluracil exceeded normal values 1.5 and 1.6 times, whereas that of histidase was 2.5 and 2.7 times as high. Carnosine and 4-methyluracil inhibited (in approximately the same degree) the formation of TBA-active products in the liver. According to morphological dta, cessation of CCl4 injections was accompanied by rapid regeneration of liver tissues in all animal groups. Carnosine enhanced regenerative processes in parenchymatous and connective tissues in a far greater degree in comparison with other drugs. The mitotic index in the carnosine-treated group exceeded more than twofold the corresponding parameters in untreated animals. Possible mechanisms of carnosine action on liver repair are discussed.
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PMID:[Effect of carnosine and 4-methyluracil on the development of experimental hepatitis in rats]. 146 55

The effects of feeding a diet deficient in zinc (Zn) to male rats on histidine metabolism were studied. Results showed that significantly higher percentages of DL-histidine-carboxyl-14C and L-histidine-2-(ring)-14C were oxidized by Zn-deficient rats. The incorporation of L-histidine-2-(ring)-14C into the proteins of skin, muscle, and kidney were significantly reduced in Zn-deficient rats as compared to Zn-supplemented rats. Conversely, the radioactivity of liver protein of Zn-deficient rats was significantly increased. Zn deficiency increased the activities of liver histidase and urocanase but had no effect on the activity of liver histidine-pyruvate transaminase. The increases of enzymatic activities were not due to food intake and can be prevented upon Zn repletion. The liver of Zn-deficient rats contained normal amount of histidine but a reduced quantity of histamine. The results on urinary excretion indicated that Zn-deficient rats discharged the same amounts of one-methyl and three-methyl histidine as Zn-supplemented pair-fed rats. Overall findings support in principle the concept that Zn deficiency results in disturbances of protein metabolism and also indicate that Zn is an important factor in regulating histidine metabolism through the urocanic acid pathway.
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PMID:Effect of zinc deficiency on histidine metabolism in rats. 612 Oct 18

Effects of histidine deficiency on muscle carnosine and anserine levels and on activities of enzymes associated with histidine catabolism and protoporphyrin synthesis were investigated. Male Sprague-Dawley (150 g) rats were tube-fed isonitrogenous, isocaloric, defined diets containing 0%, low (0.013%) or adequate (0.45%) histidine for 8-13 days. While histidine-deficient animals maintained body weight, muscle and plasma histidine and carnosine concentrations decreased rapidly and remained low following a 3-day histidine repletion period. Hepatic histidine ammonia-lyase and histidine-pyruvate transaminase activities were decreased in histidine-deficient animals, whereas formiminotransferase activity was unchanged. Hematocrit levels and hemoglobin concentrations declined progressively during histidine depletion and the activity of erythrocyte and hepatic delta-aminolevulinic acid dehydratase also decreased relative to controls. Evidence is presented indicating that decreased histidine catabolism combined with carnosine and hemoglobin degradation can provide sufficient histidine to explain the slow onset of negative nitrogen balance associated with histidine deficiency and that impaired protoporphyrin synthesis may partially explain the anemia observed in the absence of dietary histidine.
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PMID:Metabolic effects of histidine-deficient diets fed to growing rats by gastric tube. 649 66

1. The activities of the enzymes histidase, urocanase and histidine-pyruvate transaminase were studied in rats under conditions of protein malnutrition. Urocanase and histidase activities in liver were markedly lowered in experimental protein malnutrition, but the activity of histidine-pyruvate transaminase was unaffected. There is a metabolic control in vivo of the enzymes involved in the catabolism of histidine. 2. Significant changes in the urinary excretion of histidine, composition of liver and serum were apparent in the protein-malnourished rat. 3. The changes in the activities of the enzymes and other parameters were of a reversible nature and dependent on the nature of the dietary protein. 4. The significance of these findings is discussed in relation to abnormal histidine metabolism in kwashiorkor.
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PMID:Histidine metabolism in experimental protein malnutrition in rats. 1674 19