Institution: | aMOE Laboratory of Bioinorganic and Synthetic Chemistry, School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275, PR China bState Key Laboratory of Optoelectronic Material and Technologies, Sun Yat-Sen University, Guangzhou 510275, PR China cThe Key Laboratory of Gene Engineering of Ministry of Education, Sun Yat-Sen University, Guangzhou 510275, PR China |
Abstract: | Four tricationic pyridium porphyrins appending hydroxyphenyl, methoxyphenyl, propionoxyphenyl or carboxyphenyl group at meso-20-position of porphyrin core have been synthesized and their abilities to bind and cleave DNA have been investigated. Using a combination of absorption, fluorescence, circular dichroism (CD) spectra, thermal DNA denaturation as well as viscosity measurements, their binding modes and intrinsic binding constants (Kb) to calf DNA (CT DNA) were comparatively studied and also compared with those of 5,10,15,20-tetrakis(1-methylpyridinium-4-yl)porphyrin (TMPyP). The results suggest that the Kb values of these porphyrins are greatly influenced by the number of positive charges and steric hindrance. Theoretical calculations applying the density functional theory (DFT) have been carried out and explain their DNA-binding properties reasonably. The efficiency of DNA photocleavage by these porphyrins shows high dependence on the values of Kb. |