FIG. A3.

Calibration of diphenylamine assay for DNA, with either CT-DNA or AdR. (a) Reaction kinetics observed with equal amounts of CT-DNA or AdR. In DNA, only deoxyribose residues of purine nucleotides are assumed to react. (b) Ratio of the two curves in panel a, CT-DNA/AdR, after division by 0.5 (50% purines in DNA). The curve shows that the reaction with DNA (apurinic acid) is faster than the reaction with AdR and reaches a 23% higher value than expected from the assumption that the contribution of purine nucleotides in DNA to the diphenylamine reaction is equivalent to that of AdR. Blk., blank; nucleot., nucleotides.