RESUMO
A series of dicationic porphyrins were found to specifically recognize loop structures of oligodeoxynucleotides, and to selectively oxidize guanine residues upon photo-irradiation at micromolar concentrations. These compounds could, thus, be employed as promising structural probes for specific secondary DNA structures. The production of singlet oxygen ((1)O2) is responsible for the DNA-modification profiles. Both UV-titration and thermal-melting experiments indicate that the strong affinity of the charged porphyrins towards DNA loops is responsible for these molecular-recognition phenomena.
Assuntos
DNA/genética , DNA/metabolismo , Porfirinas/genética , Porfirinas/metabolismo , Sítios de Ligação/fisiologia , DNA/química , Conformação de Ácido Nucleico , Espectrofotometria Ultravioleta/métodosRESUMO
The interaction between CT-DNA and the zinc phthalocyanine ZnPc (1) was studied by UV/VIS and fluorescence titration, as well as by thermal denaturation. ZnPc was found to strongly bind to CT-DNA (K(app)=7.35 x 10(5) M(-1)) in a non-intercalative mode. The photosensitized cleavage of pBR322 DNA was found to efficiently proceed via singlet-oxygen ((1)O(2)) production. Further, ZnPc (1) caused site-specific scission of guanine (G) bases around the bulge of the hairpin oligonucleotides OD1-OD3, as clearly shown by gel-electrophoresis experiments.
