Abstract: The relationship between the yield of thymime-thymine dimer after laser irradiation and physical parameters, such as intensity and pulse number was studied to explore the function of laser irradiation to induce thymine-thymine dimer. A modified high-performance liquid chromatography (HPLC) method has been developed for the determination of thymine-thymine dimer in DNA for. The thymine-thymine dimer was prepared by a photochemical reaction to be used as the standard substance. The HPLC method we proposed is not interfered by other hydrolysate from DNA. The stability and reproducibility are good, and it can determine as little as 4.42×10^-5μg·mL^-1 thymime-thymine dimer. Three levels of laser intensity to irradiate DNA were selected from calf thymine to test the influence of the pulse number. The mechanism of DNA lesion and repair caused by laser irradiation was studied preliminarily.

Key words: Laser irradiation, Laser irradiation, DNA, DNA, Pyrimidine cyclobutane, Pyrimidine cyclobutane, HPLC, HPLC