DNA binding by adriamycin, melphalan, cis-dichloro-diammineplatinum (II) and nornitrogen mustard assessed by restriction enzyme block.

The ability of a number of DNA binding drugs to block the action of selected restriction enzymes has been used to determine the nucleotide base binding preference of these drugs. The three alkylating agents studied all displayed guanine-cytosine (G-C) base binding preference which accords with previous results for cis-DDP and with the preferred sites of alkylation being the N7 and O6 of guanine bases. Adriamycin was markedly more reactive in this assay system compared to the alkylating drugs and in contrast to these drugs showed an adenine-thymine (A-T) base binding preference.