Title: The effect of 6-mercaptopurine on nucleic acid biosynthesis in Escherichia coli.
Abstract: The growth of Escherichia coli was inhibited partially by the carcinostatic purine analog, 6-mercaptopurine (6-MP), at a concentration of 3 mgm. per liter in a glucose-salts medium, without change in viability or gross morphology of the microorganisms. Simultaneous addition of 5 mgm. of guanine per liter of medium partially reversed this inhibition without the added guanine becoming the sole source of bacterial purines. DNA and RNA purines were isolated from bacteria grown with 5 mgm. of guanine-C 14 in the presence and absence of 3 mgm. of 6-MP per liter. The relative specific activities (RSA9s) of both RNA and DNA adenine obtained from cultures grown in the presence of 6-MP were approximately 60 per cent higher than those of control cultures, whereas the corresponding guanine fractions showed only a slight increase. Utilization of exogenous guanine for the same extent of growth was unaffected by 6-MP. The increase in the RSA9s of bacterial purines was due to a lessened dilution of the labeled exogenous purine by endogenous purine since experiments with labeled formate demonstrated a reduction in endogenous purine synthesis produced by 6-MP. Although this curtailment was approximately equal for adenine and guanine, 6-MP affected the RSA9s of the nucleic acid adenine fractions more than those of the guanine fractions because a larger proportion of adenine than guanine is endogenously synthesized when guanine-C 14 is added to the growth medium.
Publication Year: 1957
Publication Date: 1957-06-01
Language: en
Type: article
Indexed In: ['pubmed']
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Cited By Count: 5
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