NUCLEOTIDE SEQUENCE OF SN-07 CHROMOPHORE BINDING SITE

DNase I footprinting was used to investigate binding sites for SN-07 chromophore on DNA fragments prepared from pBR322. Six sites were protected on about 150 base pair DNA fragments by SN-07 chromophore, but not by related anthracycline antibiotics from DNase I digestion. All the protected sites contained the dinucleotide sequence 5'-GC-3', but no other regularities could be discerned. A drug-induced conformational change of DNA was suggested by enhancement of DNase I sensitivity between the protected sites. These results support covalent interaction of the carbinolamine function of SN-07 chromophore to 2-amino group of guanine residues.