Pyrimidine dimers, single-strand breaks and crosslinks induced in DNA by powerful laser UV irradiation

Abstract

We have studied the effectiveness of the formation in DNA of photolesions such as pyrimidine dimers, crosslinks, local denatured sites and single-strand breaks induced by powerful laser UV irradiation with pulses of picosecond and nanosecond duration. The quantum yield of single-quantum products (pyrimidine dimers) at picosecond laser UV irradiation decreases with the increase of intensity. This observation proves that pyrimidine dimers are formed in DNA from excited state S P The quantum yield of two-quantum photoproducts (crosslinks, local denatured sites, single-strand breaks) grows with the increase of intensity. Inactivation of bacterial viruses and plasmids under powerful laser UV irradiation is predetermined mainly by two-quantum photolesions corresponding to single-strand breaks of DNA sugarphosphate chains.