荧光光谱法研究三唑磷对DNA的损伤作用

在生理酸度条件下(pH 7.4),采用荧光光谱法并结合溴化乙锭(EB)荧光探针、I~-离子效应、DNA熔点效应及盐效应等实验手段,研究了三唑磷与DNA的相互作用.实验发现,DNA对三唑磷的内源荧光产生强烈的猝灭,机理为动态猝灭,两者间的结合常数和结合位点数分别为4.54×10~3 L·mol~(-1)和1.082.随着DNA的加入,三唑磷的荧光强度明显减小,并且三唑磷能够竞争置换EB而猝灭DNA-EB复合物的荧光,三唑磷的加入使DNA的熔点升高,DNA的加入减小了I~-对三唑磷荧光的猝灭效应,而离子强度的增加,三唑磷自身及DNA-三唑磷体系的荧光均无明显变化.上述实验现象表明,三唑磷以嵌插方式作用于DNA的结合位点,意味着三唑磷进入生物体后有可能通过形成DNA加合物的形式造成DNA损伤,从而最终导致基因突变.

Influences of Triazophos on Potential Damage of DNA by Fluorescence Spectrophtometry

The interaction between triazophos and calf thymus DNA in physiological buffer (pH 7.4) was investigated by using ethidium bromide (EB) as a fluorescence probe.The results of fluorescence titration showed that DNA could strongly quench the intrinsic fluorescence of triazophos through a dynamic quenching procedure.The binding constant K and the number of binding sites n of triazophos with DNA were calculated to be 4.54×10~3 L·mol~(-1) and 1.082,respectively.The fluorescence quenching of the emission peak was seen in the DNA-EB system when triazophos was added,suggesting that a strong competition for DNA binding between triazophos and EB.The value of melting temperature of DNA increased in the presence of triazophos.The effect of I~- quenching on the fluorescence intensity of triazophos was reduced in the presence of DNA,and the fluorescence intensity of triazophos and DNA-triazophos didn't have a significant changes with the addition of the ion strength.Based on the above results,it can be inferred that the binding mode of triazophos with DNA is intercalative binding,the triazophos can bind to base pairs of DNA to produce DNA adducts.The triazophos might bring the chemical damage to DNA of the organisms and induce the gene mutation through producing DNA adducts.