title: Z-->B transition in poly[d(G-m5C)2] induced by interaction with 4',6-diamidino-2-phenylindole.
abstract: The Z form of poly[d(G-m5C)2], in presence of Mg2+ ion, is found to be transformed into B form upon interaction with 4',6-diamidino-2-phenylindole (DAPI). The Z-->B transformation is complete at a mixing ratio of about 0.07 DAPI per DNA base pairs, i.e., each DAPI molecule may be related to the conversion of 6-7 base pairs. An interaction between DAPI and poly[d(G-m5C)2] in its Z form at low drug: DNA ratios is suggested from optical dichroism and time-resolved luminescence anisotropy results. The spectroscopic behaviour of DAPI indicates that the Z conformation of DNA does not provide normal binding sites for DAPI, such as groove or intercalation sites, but that the initial association may be of external nature.
authors.affiliation: Department of Physical Chemistry, Chalmers University of Technology, Gothenburg, Sweden.
authors.forename: S K
authors.initials: SK
authors.lastname: Kim
authors.forename: S
authors.initials: S
authors.lastname: Eriksson
authors.forename: B
authors.initials: B
authors.lastname: Nordén
mesh_terms: D055598:Chemical Phenomena; D002627:Chemistry, Physical; D002942:Circular Dichroism; D007211:Indoles / Q000494:pharmacology*; D009690:Nucleic Acid Conformation; D011089:Polydeoxyribonucleotides / Q000737:chemistry*
chemical_list: D007211:Indoles; D011089:Polydeoxyribonucleotides; C007293:DAPI; C029988:poly(dG-m(5)dC).poly(dG-m(5)dC)