[Use of psoralen for detecting the conjugated damage to 2 chains in irradiated phage PM2 DNA].

Using psoralen for the photochemical cross-linking of DNA chains the authors have demonstrated the formation of conjugated lesions, of both opposite and non-opposite types, in X-irradiated superhelical DNA of PM2 phage. It is suggested that these lesions result from hitting a DNA molecule by a spur.