采用光谱法研究了抗癌药物喜树碱与DNA的相互作用。DNA引起喜树碱的吸收光谱轻微的红移和减色并导致喜树碱的荧光猝灭, 说明喜树碱和DNA形成基态复合物。通过计算确定了二者的结合常数, 结合位点数及主要结合力。同时考察了离子强度、磷酸根浓度、猝灭剂KI对二者相互作用的影响并比较了单、双链DNA和喜树碱相互作用的程度。变性实验确定了喜树碱-DNA复合物的熔点为60 ℃, 比纯DNA的熔点低18 ℃。实验结果表明喜树碱和DNA之间主要是沟槽作用模式。

The interaction of an anti-cancer drug camptothecin with salmon sperm DNA was studied by spectroscopic techniques. DNA induced slight hypochromic and bathochromic effects on the UV-Vis absorption spectra of camptothecin, but strong fluorescence quenching of camptothecin, which suggest the formation of ground-state camptothecin-DNA complex. The binding constant and number of binding site were calculated and the main interaction force was determined. The effect of salt, phosphate and negatively charged quencher KI on camptothecin-DNA interaction was investigated and the interaction of camptothecin with double-stranded DNA and single-stranded DNA was compared. The melting temperature of camptothecin-DNA complex was 60 ℃, which is 18 ℃ lower than that of pure DNA. All the results indicate that groove binding mode is the main interaction mode between camptothecin and DNA.