Study on DNA Intercalation and Gene Mutation by Photoproducts

UV-induced DNA damage is crucial in the onset of melanoma and other photobiological effects. If affected cells do not undergo apoptosis, the resulting DNA lesions can become mutagenic, potentially activating proto-oncogenes. The wavelength of UV radiation strongly influences the type and severity of DNA damage. Specifically UVB radiation causes the formation of DNA photoproducts through cycloaddition reactions between adjacent pyrimidine bases.

This study investigated a common type of photoproduct, the cyclobutane pyrimidine dimer (CPD), which forms through the cycloaddition of the C5-C6 double bonds of two adjacent pyrimidine bases. Another type, the pyrimidine (6-4) pyrimidone photoproduct (64PP), was studied since when exposed to large doses of UVB or UVA radiation, 64PP can undergo photoconversion, further altering its structure and increasing the risk of DNA damage.

Also, this paper studied how BaP (benzo[a]pyrene)  becomes carcinogenic only after being metabolized by enzymes into BaP diol epoxide. This metabolite was modeled using the molecular editor program when it intercalates into the DNA structure and forms covalent bonds with guanine bases, forming guanine-benzopyrene adducts.