Original Article
Nasrin Sohrabi, Nahid Rasouli,
Abstract
The association behavior of cationic metalloporphyrin, tetrakis (2, 3, 5, 6 tetrafluoro-N, N2 , Nº-trimethyl ammonium phenyl) porphyinato acetate manganese(III), [Mn(III)(TF4TMAPP)] was investigated in aqueous solutions at 25 °C and various ionic strengths using optical absorption and resonance light scattering (RLS) spectroscopies. The [Mn(III)(TF4TMAPP)] does not have any affinity for aggregation due to increasing salt concentration and exists as monomers even in high ionic strengths. Interaction of [Mn(III)(TF4TMAPP)] with ct-DNA has also been studied by optical absorption, resonance light scattering spectroscopies and thermal denaturation experiments. The appearance of hypochromicity and a bathochromicity shift inUV-vis spectra, decreasing of thermalmelting point of ct-DNA and no change in RLS spectra due to interaction with ct-DNA, represent the outside groove binding mode without any aggregate formation. The binding constants were obtained by analysis of the optical absorption spectra at various ct-DNA concentrations using SQUAD software. The thermodynamic parameters were calculated by vanÂÂÂ’t Hoff equation.