Characterization of Activation Energy Distribution for Ultraviolet Irradiation of T-Rich Oligonucleotide Using High-Performance Liquid Chromatography Electrospray Ionization Mass Spectrometry Tandem Mass Spectrometry

Abstract

Exposure to solar ultraviolet (UV) radiation gives rise to mutations that may lead to skin cancer of human beings. A series of experiments was carried out in order to reveal activation energy distribution of deoxynucleic acid (DNA) mutation caused by UV radiation. The T-rich oligonucleotides were exposed to UV radiation with increasing intensity for different durations. Photo products of T-rich oligonucleotides were investigated using ion-pair reversed-phase high-performance liquid chromatography/tandem electrospray ionization mass spectrometry at room temperature. Two photo products of T-rich oligonucleotides were cis-syn cyclobutane pyrimidine dimmer (T[c,s]T) and the pyrimidine(6,4)pyrimidone product (T[6,4]T). Activation energy distribution of DNA mutation was calculated using a commercial kinetics analysis program by Robert L. Braun and Alan K. Burnham, Lawrence Livermore International Laboratory (version 2.4.1). To use the software for deriving the kinetics parameters, the factor T (temperature) in the software was substituted with k1R, in which k1 is a factor and R is radiation intensity. The activation energy derived ranges from 55 to 110 kJ mol−1. Using the same software, those kinetic parameters were extrapolated to a natural UV radiation process to predict the degree of DNA damage without the DNA repair process.