4'-Aminomethyl-4,5',8-trimethylpsoralen

4'-Aminomethyl-4,5',8-trimethylpsoralen is a bifunctional photoreactive agent for crosslinking nucleic acids. In the dark, it intercalates into double-stranded regions in DNA or RNA. Upon long wavelength UV irradiation (e.g., 365 nm), 4'-aminomethyl-4,5',8-trimethylpsoralen first forms a covalent monoadduct with a pyrimidine base, followed by covalently linking with an adjacent pyrimidine on the opposite strand. Short wavelength UV irradiation (e.g., 254 nm) reverses this reaction. 4'-Aminomethyl-4,5',8-trimethylpsoralen has a high binding affinity for RNA and has been used to study different types of RNA from diverse organisms, including viruses.