ASYMMETRIC INTERCALATION OF N-1-(ACRIDIN-9-YLCARBONYL)SPERMINE AT HOMOPURINE SITES OF DUPLEX DNA

N-1-(Acridin-9-ylcarbonyl)spermine binds at 5'-pu-p-pu..5'-py-p-py sit es of DNA with the acridine moiety asymmetrically intercalated, stacke d between the two purine bases; the spermine moiety interacts with the homopyrimidine phosphodiester backbone of the intercalation site and protects against DNase I cleavage of this backbone, but does not prote ct against cleavage of the homopurine backbone at the same intercalati on site.