title: Sequence-dependent changes in the chiroptical properties of DNA upon interaction with dipyrandium.
abstract: Interaction of dipyrandium with DNA and its dependence on the base sequence was studied using circular dichroism. It was found that calf thymus DNA and polynucleotide duplexes with alternating purine-pyrimidine sequences containing GC basepairs underwent similar alterations in the chiroptical properties upon binding of dipyrandium. The alterations suggest that these DNAs have similar B-type structures which may kink at the dipyrandium binding sites. On the other hand, poly(dA-dT).poly(dA-dT) and especially poly(dA-dU).poly(dA-dU) exhibit some features of A-type structure. Poly(dA-dT).poly(dA-dT) changes its chiroptical properties little when complexed with dipyrandium, as if it contained some type of kinks as equilibrium structural elements.
mesh_terms: D000818:Animals; D001483:Base Sequence; D002417:Cattle; D002942:Circular Dichroism; D004247:DNA / Q000378:metabolism*; D009690:Nucleic Acid Conformation / Q000187:drug effects*; D011067:Poly dA-dT / Q000378:metabolism; D011759:Pyrrolidines / Q000494:pharmacology*
chemical_list: D011759:Pyrrolidines; D011067:Poly dA-dT; C004861:dipyrandium; D004247:DNA