Abstract:

The interaction between pirimicarb and calf thymus DNA was studied by UV absorption spectroscopy, fluorescence spectroscopy and melting point measurement in the respective presence of Cu2+, Ca2+ and Mg2+ in physiological buffer (pH 7.4). From the results of ethidium bromide (EB) competition and DNA melting point measurement, pirimicarb reacted with DNA basic groups mainly through intercalative binding. All the three metal ions were found to be able to complex with pirimicarb, and the generation of complexes made a difference to the ultraviolet absorption peak intensity and shape of the reaction systems and quenched the fluorescence intensity of the EB/DNA complex to different extents. In the respective presence of Cu2+ and Ca2+, the binding constant of the DNA/pirimicarb complex initially decreased, followed by increase, and the involvement of Mg2+ could enhance the binding between DNA and pirimicarb. It can be concluded that the binding between DNA and pirimicarb mainly depends on the relative affinity ratio between metal ions and DNA basic groups or phosphate groups.

Key words: metal ions, pirimicarb, calf thymus DNA, fluorescence spectrum, intercalative binding