STUDIES IN METABOLIC SPECTRA IV

Abstract

Cheng, Lorraine (Radiobiochemistry Department, Chas. Pfizer & Co., Inc., Maywood, N. J.) and J. F. Snell . Studies in metabolic spectra. IV. Effects of tetracyclines, some of their derivatives, and chloramphenicol on accumulation of glutamic acid in Escherichia coli . J. Bacteriol. 83: 711–719. 1962.— Escherichia coli strain 21 was incubated in the Warburg apparatus at 37 C with sodium acetate-2-C ¹⁴ and 0.1 μmole/ml of various test compounds. Up to 1 hr, de novo C ¹⁴ -glutamic acid (synthesized from the C ¹⁴ -acetate precursor) accumulation in the fermentation broth was found to be a common phenomenon for the control cells and cells treated with oxytetracycline, chlortetracycline, tetracycline, and chloramphenicol. Subsequently, C ¹⁴ -glutamic acid continued to accumulate in the broth of the inhibited cells, but began to disappear from the broth of the control cells. During the first half hour, the rate of accumulation was most rapid in the presence of oxytetracycline. At 3 hr the total de nova C ¹⁴ -glutamic acid was found to be the same whether cells were treated with oxytetracycline or not. However, the distribution of this glutamic acid was different. In the oxytetracycline-treated cells, more than 87% of the total de nova C ¹⁴ -glutamic acid was in the broth, and only 13% was incorporated into the cell residue. In the control cells, no C ¹⁴ -glutamic acid was found in the broth, although 67% was in the cell residue. The possibility that the tetracyclines and chloramphenicol have different modes of action, and that oxytetracycline inhibits the incorporation of d -glutamic acid into the cell wall and membrane material in E. coli 21, was discussed.