Tyrosine‐sensitized Photodimerization of Thymine in Aqueous Solution

Abstract

Abstract. Photodimerization of thymine in aqueous solution in the presence of tyrosine was studied with monochromatic UV irradiation. The total dimer formation was sensitized in the presence of tyrosine. The action spectrum of sensitized total dimer formation has a peak near 280 nm corresponding to the absorption maximum of tyrosine. Triplet quenchers reduced the sensitization substantially. It seems probable that tyrosine‐sensitized photodimerization of thymine occurred via triplet‐triplet energy transfer from tyrosine to thymine.

Cross-Linking of Proteins to Nucleic Acids by Ultraviolet Light

“…Recently Kaneko et al (1978) have shown that tyrosine can photosensitize the dimerization of thymine in aqueous solution. This was shown to occur via triplet-triplet energy transfer.…”

Photosensitized formation of thymine dimers in DNA by tyramine, tyrosine and tyrosine containing peptides

“…Smith proposed the hypothesis that DNA-protein cross-linking contributea to the inactivation and showed the parallelism between the killing of cells and the loss of extractability of DNA (1). Concerning the participation of protein in the inactivation of cells, we proposed the possibility that the formation of ThyOThy in DNA by UV irradiation was sensitized by tyrosine residues by the triplet-triplet energy transfer from tyrosine to Thy (2). This hypothesis is based on the triplet-triplet energy transfer from histone to DNA in deoxyribonucleohistone observed by the phosphorescence spectra (3) and it was verified in the case of Thy monomer and tyrosine in aqueous solution (2).…”

“…Concerning the participation of protein in the inactivation of cells, we proposed the possibility that the formation of ThyOThy in DNA by UV irradiation was sensitized by tyrosine residues by the triplet-triplet energy transfer from tyrosine to Thy (2). This hypothesis is based on the triplet-triplet energy transfer from histone to DNA in deoxyribonucleohistone observed by the phosphorescence spectra (3) and it was verified in the case of Thy monomer and tyrosine in aqueous solution (2). In the present work, we observed the photosensitized formation of ThyO Thy in DNA in vitro by tyramine, tyrosine and tyrosine-containing peptides.…”