Experiments were conducted with intact rat hepatocytes to identify inhibitors and incubation conditions that cause selective inhibition of alanine aminotransferase or aspartate aminotransferase. Satisfactory results were obtained by preincubating cells with L-cycloserine or L-2-amino-4-methoxy-trans-but-3-enoic acid in the absence of added substrates. When cells were incubated for 20 min with 5...

The blue-green alga Anacystis nidulans (strain L 1402-1) was grown at +37 degrees C in air (0.03 vol% CO2 and in air enriched with 3.0 vol% CO2. The effects of several inhibitors on the activity of aminotransferases, 14CO2 fixation and radioactive photosynthetic products of Anacystis were studied. No serine-pyruvate aminotransferase activity could be found in 10-2 M isonicotinyl hydrazide (INH)...

Dexamethasone induces the synthesis of tyrosine aminotransferase in hepatoma tissue culture (HTC) cells, an established line of rat hepatoma cells in tissue culture. The addition of insulin or dialyzed serum to cells previously induced with dexamethasone in a serum-free medium causes a further doubling in tyrosine aminotransferase activity, which is not dependent on concomitant RNA synthesis. T...

The activities of the amino acid-catabolizing enzymes, serine dehydratase (EC 4.2.1.16), ornithine aminotransferase (EC 2.6.1.13), tyrosine aminotransferase (EC 2.6.1.5), and alanine aminotransferase (EC 2.6.1.12), were measured in the livers of rats bearing the Morris 7800 hepatoma for varying periods. A relatively rapid decrease in the activities of hepatic serine dehydratase and orni thine a...

Organelles in spinach leaves were isolated in sucrose gradients by isopycnic centrifugation. The peroxisomal fraction was the only cellular site for two different and irreversible aminotransferases which utilized glyoxylate as the amino acceptor in the formation of glycine. These were a serine:glyoxylate aminotransferase with a specific activity of 1.54 pmoles X min-1 X mg-1 peroxisomal protein...

We examined the effect of pyridoxal phosphate supplementation on the apparent aspartate aminotransferase (EC 2.6.1.1.) activity of human serum. Supplementation by 25 mol/liter effected an average increase of 16% in the results for kinetic assay. The increase was not the result of increased enzymatic or nonenzymatic blanks, and, within a small range, sample dilution had no significant effect. Pa...

1. Alanine Aminotransferase (ALT) Alanine aminotransferase measurements are used in the diagnosis and treatment of certain liver diseases (e.g., viral hepatitis and cirrhosis) and heart diseases. Elevated levels of the transaminases can indicate myocardial infarction, hepatic disease, muscular dystrophy, or organ damage. Serum elevations of ALT activity are rarely observed except in parenchymal...

We measured the activities of two mitochondrial enzymes, the mitochondrial form of aspartate aminotransferase (EC 2.6.1.1) and glutamate dehydrogenase (EC 1.4.1.2), in the serum of apparently healthy persons (n = 84) and patients suffering from chronic liver diseases (n = 43). The distribution of activities for glutamate dehydrogenase, but not mitochondrial aspartate aminotransferase, was sex-d...

Two clonal lines of rat hepatoma cells, in tissue culture, that have steroid-inducible tyrosine aminotransferase (TAT) activities were shown to have different responses to amphotericin B. One of the cell lines (HTC) was relatively resistant to the growth-inhibiting effects of amphotericin B and demonstrated an inhibition of only its steroid-inducible TAT activity when exposed to the antifungal ...

Subcutaneous administration of L-thyroxine (75 pg/lOO g of body weight per day) to rats for 10 to 14 days caused a decrease in the activity of kynurenine 3-hydroxylase to about 50% of the control value. Enzymic properties of kynurenine 3-hydroxylase of mitochondrial outer membrane preparations isolated from normal and L-thyroxine-treated rats were almost identical, suggesting that L-thyroxine a...