THE REACTION OF TRIPLET 2-METHYL-1,4-NAPHTHOQUINONE (MENADIONE) WITH DNA AND POLYNUCLEOTIDES

The photoreaction of 2-methyl-1,4-naphthoquinone (MQ, menadione) with DNA and polynucleotides in argon-saturated aqueous solution (pH 7) was studied. Results from laser flash photolysis experiments indicate tha t triplet quinone reacts with DNA and polyA but not detectably with po lyU by one-electron oxidation of the bases of the nucleic acid with fo rmation of the radical anion of the quinone. Irradiation of argon-satu rated solutions containing MQ and DNA or polynucleotides (polyU, polyA , polyG or polyC) with 334 nm light leads to an increase in molecular weight for single-stranded DNA, polyA and to a much less extent for po lyU. This finding indicates crosslink formation with quantum yields in the range of 10(-5)-10(-3).