Quantitative Determination of Cross-linkage of Bacteriophage DNA and Protein by Ionizing Radiation

Summary

Coliphage T7 was dissolved in tryptone broth and exposed to ⁶⁰C gamma-radiation. Cross-linkage of DNA and protein of the virion was assayed using phenol–water countercurrent distribution. The results are interpreted in terms of a statistical model of cross-linkage and double-strand breaks. It was found that protein–DNA cross-links accumulate linearly with dose at a rate of 0·74 × 10⁻¹¹ cross-links per rad per nucleotide pair, which is of the order of 5 per cent of the formation rate of double-strand breaks.