Spinelli M, Dabrowiak J C
Biochemistry. 1982 Nov 9;21(23):5862-70. doi: 10.1021/bi00266a021.
The interaction of Cu(II) with the native and heat-denatured DNA complexes of daunomycin (1) and N-(trifluoroacetyl)daunomycin (3) has been examined by using absorption and circular dichroism spectroscopies. At low rt, where rt is the input molar ratio of drug to DNA phosphate, Cu(II) interacts with the native and heat-denatured calf thymus DNA complex of daunomycin to form a ternary complex involving the aglycon portion of the antibiotic, Cu(II), and DNA. A Job plot of the titration involving Cu(II) and heat-denatured DNA shows that the Cu(II)-drug stoichiometry in the ternary complex is less than or equal to 1. Although the N-(trifluoroacetyl)daunomycin-native DNA complex does not form a ternary complex, the denatured DNA complex with the antibiotic does. Copper(II) titrations of the daunomycin-native DNA complex, at high rt, where both strongly and weakly bound antibiotic molecules are very likely present in solution result in the formation of both the ternary species as well as a binary complex involving only the metal ion and the antibiotic. The spectroscopic results indicate that in the ternary complex, the Cu(II) ion is bound to the unintercalated aglycon portion of the antibiotic and very likely also to the heterocyclic bases of DNA.
通过吸收光谱和圆二色光谱研究了铜（II）与柔红霉素（1）和N-（三氟乙酰基）柔红霉素（3）的天然及热变性DNA复合物的相互作用。在低rt（rt为药物与DNA磷酸基团的输入摩尔比）时，铜（II）与柔红霉素的天然及热变性小牛胸腺DNA复合物相互作用，形成一种三元复合物，其中涉及抗生素的糖苷配基部分、铜（II）和DNA。涉及铜（II）和热变性DNA的滴定的Job曲线表明，三元复合物中铜（II）与药物的化学计量比小于或等于1。虽然N-（三氟乙酰基）柔红霉素-天然DNA复合物不形成三元复合物，但抗生素与变性DNA的复合物能形成。在高rt时对柔红霉素-天然DNA复合物进行铜（II）滴定，此时溶液中很可能同时存在强结合和弱结合的抗生素分子，结果会形成三元物种以及仅涉及金属离子和抗生素的二元复合物。光谱结果表明，在三元复合物中，铜（II）离子与抗生素未插入的糖苷配基部分结合，很可能还与DNA的杂环碱基结合。
