摘要：

The rate of depurination of double-stranded Bacillus subtilis DNA, radioactively labeled in the purine residues, has been followed as a function of temperature, pH, and ionic strength. In a Mg2+-containing buffer of physiological ionic strength, the rate constant for depurination of DNA is 4 × 10-9 sec-1 at 70° and pH 7.4. The activation energy of the reaction is 31 ± 2 kcal/mole. These data strongly indicate that depurination of DNA occurs at a physiologically significant rate under in vivo conditions and consequently that the lesions introduced in this fashion must be repaired.

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