Label-Free Monitoring of DNA–Ligand Interactions (original) (raw)

1997, Analytical Biochemistry

sess, e.g., anti-tumor, anti-viral, or anti-microbial activ-We report on the label-and isotope-free monitoring ity, and certain substances are of pharmacological and of DNA interactions with low-molecular-weight limedical importance (2). Many anti-tumor drugs exert gands. An optical technique based on interference at their action by interfering with the function of DNA. thin layers was used to monitor in real time binding Modes of interaction include noncovalent binding such as of ligands at DNA which was immobilized by Coulomb intercalation and groove binding (1), drug-DNA adduct interactions at a positively charged surface. Approxiformation, e.g., by cisplatin covalent binding , and mately 2 ng DNA/mm 2 was irreversibly bound to the DNA backbone scission, e.g., by bleomycin or enediyne surface, which remained stable over several days. This antibiotics (4, 5). Anthracycline antibiotics constitute an result was confirmed by characterization of the layer important family of intercalative anti-tumor drugs and using spectroscopic ellipsometry. During incubation some of them, e.g., doxorubicin (6), have been used cliniof immobilized DNA with a variety of intercalators and cally as components in chemotherapeutic treatments of other DNA-binding compounds in a flow system, interdifferent kinds of cancer. Intercalators bind to DNA by actions were monitored by reflectometric interference inserting their planar chromophores between adjacent spectroscopy. Binding effects between 10 and 400 pg/ DNA base pairs. Frequently, these complexes are further mm 2 were detected unambiguously. Nonspecific bindstabilized by hydrogen bond formation between the DNA ing effects were excluded by using a negatively bases and the sugar moieties appended to the aglycon.