ABSTRACT

UV irradiation of DNA is known to cause damage to the genetic information. DNA contains four nucleic acid bases where purine bases such as adenine and guanine are stable to UV light, but pyrimidine bases of thymine (uracil in RNA) and cytosine are unstable to UV light. Thymine bases in DNA undergo photodimerization via UVirradiation at 270 nm to form the photodimer. The photodimerization occurs at a thymidine sequence where the thymine bases stack with each other (Figure 104.1).