title: DNA interactions of cisplatin tethered to the DNA minor groove binder distamycin.
abstract: Modifications of natural DNA in a cell-free medium using cisplatin tethered to the AT-specific, minor groove binder distamycin, were studied using various methods of biochemical analysis or molecular biophysics. These methods include: binding studies using differential pulse polarography and flameless atomic absorption spectrophotometry, mapping DNA adducts using a transcription assay, use of ethidium bromide as a fluorescent probe for DNA adducts of platinum, measurement of DNA unwinding by gel electrophoresis, measurement of CD spectra, an interstrand cross-linking assay using gel electrophoresis under denaturing conditions, measurement of melting curves with the aid of absorption spectrophotometry and the use of terbium ions as a fluorescent probe for distorted base pairs in DNA. The results indicate that attachment of distamycin to cisplatin changes several features of the DNA-binding mode of the parent platinum drug. Major differences comprise different conformational alterations in DNA and a considerably higher efficiency of the conjugated drug to form in DNA interstrand cross-links. Cisplatin tethered to distamycin, however, coordinates to DNA with similar base sequence preferences as the untargeted platinum drug. The results point to a unique profile of DNA binding for cisplatin-distamycin conjugates, suggesting that tethering cisplatin to minor groove oligopeptide binders may also lead to an altered biological activity profile.
authors.affiliation: Institute of Biophysics, Academy of Sciences of the Czech Republic, Brno.
authors.forename: H
authors.initials: H
authors.lastname: Loskotová
authors.forename: V
authors.initials: V
authors.lastname: Brabec
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D001483:Base Sequence; D002474:Cell-Free System; D002942:Circular Dichroism; D002945:Cisplatin / Q000494:pharmacology*; D003432:Cross-Linking Reagents / Q000494:pharmacology; D004247:DNA / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure*; D018736:DNA Adducts; D004278:DNA, Superhelical; D004268:DNA-Binding Proteins / Q000737:chemistry; D004214:Distamycins / Q000494:pharmacology*; D004591:Electrophoresis, Polyacrylamide Gel; D004996:Ethidium / Q000494:pharmacology; D007364:Intercalating Agents / Q000494:pharmacology; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D010455:Peptides / Q000737:chemistry; D011485:Protein Binding; D013997:Time Factors; D014158:Transcription, Genetic
chemical_list: D000970:Antineoplastic Agents; D003432:Cross-Linking Reagents; D018736:DNA Adducts; D004278:DNA, Superhelical; D004268:DNA-Binding Proteins; D004214:Distamycins; D007364:Intercalating Agents; D010455:Peptides; C030000:stallimycin; D004247:DNA; D004996:Ethidium; D002945:Cisplatin