Photoreactivity of 5-iodouracil-containing telomeric DNA.

The photoreaction of 5-iodouracil-((I)U)-containing telomeric oligonucleotides in parallel or antiparallel structures, generated in the presence of K+ or Na+ ions, was investigated. It was found that the photoreactivity of telomeric DNA depends on the differences in the quadruplex conformations in the presence of K+ or Na+ ions.