Effect of DNA intercalators on poly(ADP-ribose) glycohydrolase activity

Proflavine, ethacridine (2-ethoxy-6,9-acridine diamine), ellipticine, daunomycin and Tilorone R10,556 DA (2,7-bis(piperidinobutyryl)-9H-fluoren-9-one) inhibit poly(ADP-ribose) glycohydrolase activity. The Ki values for proflavine and Tilorone R10,556 DA are 36 microM and 7.3 microM, respectively. The inhibition by intercalators is relieved by DNA but not by DNA-histone complexes. On the contrary, DNA-histone complexes increase the inhibition of some intercalators. Ethidium bromide is not inhibitory by itself. However, in the presence of DNA-histone complexes it strongly inhibits the enzyme activity. m-AMSA (4'-(9-acridinylamino)methanesulphon-m-anisidide) and chloroquine have no effect on the enzyme activity, even in the presence of DNA-histone complexes.