Interaction of papaverine with covalently closed DNA

Cyclic nucleotides influence viral replication and papaverine, as an inhibitor of phosphodiesterase, also affects the replication of both DNA and RNA viruses through an increase in cAMP levels. Moreover in vitro papaverine affects neither protein synthesis nor several polymerases, while it inhibits DNA synthesis. Static fluorescence studies on the interaction of the drug with ColE1 plasmid covalently closed DNA indicate that the drug binds to the nucleic acid, probably by intercalation. A comparison between the binding characteristics of Papaverine and Actinomycin D is also reported.