Specific Binding of SN-07 Chromophore, an Anthracycline Antibiotic, to DNA

SN-07 chromophore is an anthracycline antibiotic, but is atypical in the group because it contains an eight-membered ring with the carbinolamine structure. We constructed the SN-07 chromophore-DNA complex and investigated the binding mode of SN-07 chromophore to DNA. SN07 chromophore was released from the SN-07 chromophore-poly(dl-dC)•poly(dl-dC) complex, but not from the SN-07 chromophore-poly(dG-dC)•poly(dG-dC) complex, and carminomycin III was released from both DNA complexes by the HPLC analysis. It was suggested that the carbinolamine structure of SN-07 chromophore had a specific selectivity to DNA binding and the 2-amino group of guanine had an important role, so SN-07 chromophore was very different from the related anthracycline antibiotics. SN-07 chromophore-λDNA complex was resistant to digestion by an excess of a number of restriction enzymes, but the carminomycin III-λDNA complex was sensitive. We showed that the restriction enzyme recognized GC, the HhaI reaction was strongly inhibited by SN-07 chromophore in the complex, but the restriction enzyme recognized AT, and the DraI reaction was not. Inhibition intensity was due to the recognition sequence and its neighboring sequence. It was evidenced that SN-07 chromophore had the sequence specificity of the binding to DNA and its preferred sequence was 5'-GC-3'.