Interaction Between DNA and 8-Methoxypsoralen Studied by Linear Dichroism

Journal article, 1979

High sensitivity linear dichroism on DNA oriented by flow is shown to provide conclusive information about the interaction with 8–methoxypsoralen (8–MOP) both in the dark and by irradiation. 8–MOP forms directly in the dark a weak complex with DNA with a structure consistent with the intercalation model of Lerman. When aqueous DNA-psoralen solutions are UV irradiated (30800 nm). a photoadduct is formed. By comparison with experiments in ice matrix, it is suggested that it is the primarily bound 8–MOP that is responsible for the final product. It is inferred that this product is the 41,5I-photoadduct of 8–MOP. The orientation of the photo adduct on DNA is not consistent with intercalation.