Abstract:

The interaction between fenthion and calf thymus DNA in physiological buffer (pH 7.4) was investigated by UVvis spectroscopy, fluorescence spectroscopy, viscosity measurement, salt effect, phosphate effect and KI fluorescence quenching effect. The fluorescence intensity of fenthion was significantly reduced with the addition of DNA. The binding constant and number of binding sites of fenthion with DNA were calculated as being 1.14×104 L/mol and 0.958, respectively. There were no obvious fluorescence quenching effect found on the emission peak of DNA-ethidium bromide (EB) system when fenthion was added, suggesting that there is no competition for DNA binding between fenthion and EB. Neither the relative viscosity of DNA nor the fluorescence intensity of fenthion and fenthion-DNA showed significant changes with the addition of fenthion and sodium chloride. The quenching effect of I― on the fluorescence intensity of fenthion was increased in the presence of DNA. Based on the above results, it can be inferred that fenthion and DNA interact in a groove-binding mode.

Key words: fenthion, DNA, fluorescence spectroscopy, binding mode