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Updated: Oct 5, 2026

Single Molecule Analysis of Laser Localized Psoralen Adducts
Published on: April 20, 2017
Formation of cyclobutane thymine dimers from UVA photosensitization of pyridopsoralen monoadducted DNA
L A Guillo1, B Beylot, P Vigny
1Departmento de Bioquimica, Universidade de Sao Paulo, Brazil.
Abstract:
The present report provides evidence that thymine dimerization can be UVA photosensitized at a tetranucleotide, 5'-TATT-3', by a 7-methyl-pyrido(3,4-c)psoralen monoadduct in DNA. The efficiency of the photoprocess depends on the tetranucleotide flanking sequences. These results demonstrate that one DNA lesion can originate the contiguous formation of a second type of lesion and emphasize the sequence-specific response to interaction of drugs with DNA. Results are related to the sensitivity of DNA to 1,10-phenanthroline-cuprous ion complex nucleolytic activity and discussed in terms of the major role of local deformability of DNA in interaction with ligands.
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