P-3A and (−)-desacetamido P-3A: demonstration and Study of their effective functional cleavage of duplex DNA

A study of the Fe(II) complexes of P-3A (1) and (?)-desacetamido P-3A (2) abilities to cleave duplex DNA was conducted through examination of single-strand and double-strand cleavage of supercoiled φX174 RFI DNA (Form I) in the presence of O₂ to produce relaxed (Form II) and linear (Form III) DNA, respectively. Like Fe(II)-bleomycin A₂ and deglycobleomycin A₂, Fe(II)-1 and 2 effectively produced both single- and double-strand cleavage of supercoiled φX174 DNA. Unlike Fe(II)-bleomycin A₂ or deglycobleomycin A₂, Fe(II)-1 and 2 were found to cleave duplex w794 DNA with no discemible sequence selectively suggesting that the polynucleotide recognition of the C-terminus tetrapeptide S subunit of the bleomycins including the bithiazole may dominate the bleomycin A₂ DNA cleavage selectivity.