Yamamoto Itaru
Jun 1, 1969
Citations
0
Influential Citations
27
Citations
Quality indicators
Journal
Biochemical Pharmacology
Abstract
Abstract 4(or 5)-Diazoimidazole-5(or 4)-carboxamide (Diazo-ICA) and dialkyl-triazenoimidazoles tested at concentrations of 1 μg/ml and 10 μg/ml, completely inhibit the growth of Escherichia coli B without causing cell lysis. With the latter compounds there is a lag period before growth inhibition. After exposing growing cells to 0.1–0.5 μg/ml of Diazo-ICA for 60 min, the number of viable cells was only about 5 per cent of that before exposure. This compound also affects resting cells. The inhibitory effect of Diazo-ICA can be abolished by the addition of cysteine, but 4(or 5)-aminoimidazole-5(or 4)-carboxamide, hypoxanthine, DNA, RNA, protein and leucine have no affect on the inhibition. At relatively high concentration, 2- azahypoxanthine, which is a cyclized product of Diazo-ICA, also inhibits cell growth, but its effect is abolished by the addition of hypoxanthine. Diazo-ICA, at a concentration of 0.05 μg/ml, inhibits the biosynthesis of DNA in the cells, whereas synthesis of RNA is slightly stimulated and synthesis of protein is not affected. In E. coli B cells incubated with Diazo-ICA (0.01 μg/ml), the incorporation of thymidine-3H into DNA is severely inhibited. However, the incorporation of uridine-3H into RNA is slightly stimulated and that of leucine-3H into protein is not inhibited. These results suggest that the major action of Diazo-ICA in E. coli B is to inhibit DNA synthesis, by interfering with SH-groups in biological systems.