Cleavage of double-stranded DNA by manganese tris(methylpyridiniumyl)porphyrin linked to 3'-spermine oligonucleotides

Cleavage of double-stranded DNA was performed with cationic manganese porphyrin complexes linked via a spermine tether to the 3'- or 5'-side of triple-helix-forming oligonucleotides (cleaver-TFO conjugates). The targeted sequence was a 15-polypurine sequence present in the env gene of HIV-1 (positions 7301-7315). The presently used TFOs contain only thymine and 5-methylcytosine residues and one adenine at the 3'-end in order to be able to easily introduce a 3'-polyamine linker by reductive amination of the corresponding 3'-apurinic polypyrimidine oligonucleotides. With this method we prepared these TFO-cleaver conjugates in 45% yield with only two equivalents of the Mn-TrisMPyP-COOH precursor. These new metalloporphyrin-TFO conjugates were able to cleave a complementary 45-mer duplex at 10 nM concentration with only ten equivalents of TFO-cleaver. Conjugates without spermine, without 5-methylcytosine, with a random sequence or with the managanese porphyrin-spermine entity on the 5'-end of TFOs were synthesized for comparative studies.