Relationship Between Escherichia coli B Titer and the Level of Deoxycytidylate Deaminase Activity Induced on Bacteriophage T2r+ Infection

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RESUMO

The activities of six bacteriophage T2r+-induced enzymes (thymidylate synthetase, deoxycytidylate deaminase, thymidylate kinase, deoxycytidylate hydroxymethylase, deoxycytidine pyrophosphatase, and dihydrofolate reductase) were measured after dilution of phage-infected Escherichia coli B from 8 × 108 to 2 × 108 cells per ml. The only enzyme activity altered was that of deoxycytidylate deaminase, which increased three- to fourfold. Conversely, the rapid concentration of cells from 2 × 108 to 8 × 108 per ml did not result in a reduction in deaminase activity. Although an enhancement in aeration reduced the response of deoxycytidylate deaminase to cellular dilution, the influence of potential metabolic inhibitors or activators could not be shown. The change in deoxycytidylate deaminase activity appeared to be associated with an altered translational event, since the increase could not be prevented by rifampin but was blocked effectively by chloramphenicol and hydroxylamine. In addition, antibody to the T2 phage-induced deoxycytidylate deaminase demonstrated that the increase in enzyme activity was associated with a corresponding increase in radioactive leucine incorporated into the enzyme antigen.

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