In Saccharomyces cerevisiae, 3-amino-1,2,4-triazole (aminotriazole) competitively inhibits the activity of imidazoleglycerolphosphate dehydratase, the product of the HIS3 gene. Wild-type strains are able to grow in the presence of 10 mM aminotriazole because they induce the level of imidazoleglycerolphosphate dehydratase. However, strains containing gcn4 mutations are unable to grow in medium c...

Seedlings of tobacco (Nicotiana sylvestris) were treated in vivo with 0.03 to 20 millimolar 3-amino-1,2,4-triazole (aminotriazole). There was a rapid loss of catalase (EC 1.11.1.6) activity over the first 5 hours followed by a slower decrease for the next 4 hours to a level that was 15 to 20% of the initial activity, with little or no change for periods up to 3 days. Fifty percent loss of catal...

It was first shown by Heim et al. (2, 3) that 1 hour after S-amino-l ,2,4-triazolel has been injected into rats, there is a marked inhibition of liver and kidney catalase, a lesser inhibition of liver peroxidase, and no inhibition of erythrocyte catalase activity. In view of this rather selective action towards tissue hydroperosidases, it seemed possible that aminotriazole should exhibit antith...

It was first shown by Heim et al. (2, 3) that 1 hour after S-amino-l ,2,4-triazolel has been injected into rats, there is a marked inhibition of liver and kidney catalase, a lesser inhibition of liver peroxidase, and no inhibition of erythrocyte catalase activity. In view of this rather selective action towards tissue hydroperosidases, it seemed possible that aminotriazole should exhibit antith...

Studies were performed to elucidate the nature of the pathway of hepatic thyroxine (T4) metabolism that is activated by inhibitors of liver catalase. For this purpose, the metabolism of T4 in homogenates of rat liver was monitored with T4 labeled with 125I either at the 5'-position of the outer-ring (125I-beta-T4) or uniformly in both the outer and inner rings (125I-U-T4). In homogenates incuba...

The catalase-aminotriazole assay for determination of hydrogen peroxide apparently cannot be used for measuring hydrogen peroxide production in crude preparations from wood decay fungi because of materials in the crude preparations that interfere with the test.

The ability of intact human red cells to scavenge extracellularly generated H2O2 and O2-, and to prevent formation of hydroxyl radicals and hypochlorous acid has been examined. Red cells inhibited oxidation of ferrocytochrome c by H2O2. Cells treated with aminotriazole no longer inhibited, indicating that protection was almost entirely due to intracellular catalase. Contribution by the GSH syst...

Diuron and bentazon are very strong inhibitors of the photosynthetic electron transport in isolated radish chloroplasts. The chlorosis producing herbicide SAN 6706 also inhibited the photosystem II dependent oxygen evolution. Aminotriazole had no effect. The inhibitor concentration for 50% inhibition of photosystem II activity was 10-7 m for diuron and 10-4 m for bentazon and SAN 6706 respectiv...

protein pigment of microsomes and probably have an important role for the oxidation of drugs (4-10). Recently, Granick and Urata demonstrated that the administration of many drugs, including phenobarbital, markedly increased the activities of 6-amino levu Ionic acid synthetase and synthesis of porphyrine (11, 12). These results suggested that the increase in the activities of drug-metabolizing ...