金属离子Cu2+、Ca2+和Mg2+对抗蚜威与DNA结合作用的影响

在人体生理酸度(pH7.4)下，运用紫外、荧光光谱法和DNA 熔点实验研究抗蚜威与小牛胸腺DNA 的作用方式以及Cu2+、Ca2+ 和Mg2+ 分别对两者结合的影响。溴化乙锭(EB)竞争实验和DNA 熔点测定结果表明，抗蚜威主要是通过嵌插方式与DNA 碱基发生作用。3 种金属离子均能与抗蚜威络合，络合物的生成使体系的紫外吸收峰强度和形状发生改变，并能不同程度地猝灭DNA-EB 复合物的荧光；Cu2+、Ca2+ 的存在使DNA- 抗蚜威复合物的结合常数呈现先减弱后增强的趋势，而Mg2+ 的参与能增强两者之间的结合。由此推断出，金属离子对抗蚜威与DNA 结合的影响主要取决于金属离子与DNA 的碱基和磷酸基团间结合的相对亲和比。

Effects of Cu2+, Ca2+ and Mg2+ on the Interaction of Pirimicarb with Calf Thymus DNA

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.