THE EFFECT OF DIPHTHERIA TOXIN ON THE METABOLISM OF HELA CELLS : II. EFFECT ON NUCLEIC ACID METABOLISM

The effect of toxin on the incorporation of uridine and thymidine into nucleic acids was investigated. P³² orthophosphate incorporation into the nucleoside phosphate fraction was also investigated. No early effect of toxin on nucleic acid synthesis was evident and only a slight effect of toxin on nucleoside phosphate formation was found prior to 1.5 hours after toxin addition. Both these processes, however, were found to be sensitive to dinitrophenol. These results are interpreted as indicating that toxin does not act by a general uncoupling of oxidation from phosphorylation. Other possible mechanisms of toxin action are proposed.