Table 2. Quantification of the effect of C5-methylation on the pyrimidine dimerization following irradiation at 255 nm by the parameter I m=ϕ m ψ n/ϕ n ψ m accounting for the different absorption spectra of C and 5mC; ϕ m and ϕ n are the quantum yields found for the methylated and the corresponding non-methylated system, respectively (Table 1); ψ m and ψ n represent the fraction of photons absorbed by a reactive 5mC or C.
Abbreviations: CPD, cyclobutane pyrimidine dimer; 64, pyrimidine (6-4) pyrimidone adducts.