Influence of DNA topology on the photoreactions of various psoralen derivatives with duplex DNAs

Abstract Psoralens are plant-derived compounds that intercalate into duplex DNAs and form covalent bonds with thymine bases upon ultraviolet A irradiation. When included in AT/TA sequences, psoralen photoreactions generate interstrand cross-links that disrupt essential DNA processes, including replication and transcription. Here, we investigated how DNA topology influences the photoreactions of various psoralen derivatives in duplex DNAs. We found that the psoralen derivative 4′-aminomethyl-4,5′,8-trimethylpsoralen scarcely photoreacted with duplex DNAs but exhibited high photoreactivity for negatively supercoiled DNA. Other psoralen derivatives examined in this study did not display similar behavior.