THE LINKING CHAIN-LENGTH IN BRIDGED ALDEHYDE-SUBSTITUTED PYRIDINIUM DIMERS MODULATES A SLOW REVERSIBLE BINDING THAT AFFECTS SUPERCOILING OFPLASMID DNA

Bridged aldehyde substituted pyridinium dimers bind to DNA. Binding in duces retardation of the electrophoretic migration of circular plasmid due to relaxation of supercoiling. Binding to DNA is slow and reversi ble and depends on the length of linking chain, pH, ionic strength and temperature. It is postulated that release of topological stress resu lts from the disruption of hydrogen bonding between complementary base s, a hypothesis consistent with facilitated attack of DNA by formaldeh yde promoted by the bridged compounds.