PHOTOBIOLOGICAL PROPERTIES OF METHYLENE VIOLET

The interaction of methylene violet (MV) and 4-bromomethylene violet ( BrMV) with calf thymus and supercoiled Phi X174 phage RF I DNA is repo rted. Measurements employing UV-visible absorption spectroscopy and eq uilibrium dialysis give evidence for the formation of complexes by eac h dye with DNA in the dark. They covalently bind to DNA, and MV nicks DNA, when the nucleic acid/dye mixtures are irradiated with visible li ght in a deoxygenated environment. Quantum efficiencies for singlet ox ygen formation are 0.27 and 0.25 for MV and BrMV, respectively. A high er value (0.49) is observed for 4-iodomethylene violet (IMV).