title: Z-DNA and other non-B-DNA structures are reversed to B-DNA by interaction with netropsin.
abstract: The interaction between the B-form specific ligands netropsin (Nt) and distamycin-3 (Dst-3) and DNA duplexes has been studied under conditions of salt concentration and low water activity that modify the polymer conformation into a non-B DNA form, putatively a Z-like form. Three polymers with strict alternating purine-pyrimidine sequences and GC content from 100-0% have been tested: poly(dG-dC) . poly(dG-dC), poly(dA-dC) . poly(dG-dT) and poly(dA-dT) . poly(dA-dT). The titrations by Nt and Dst-3 were followed by circular dichroism. Although specific binding of Nt to the Z-form of poly(dG-dC) . poly(dG-dC) does not occur, Nt reverses this Z structure to the B-type conformation; Dst-3 is, however, totally inefficient. The presumed non-B or Z-like structure of poly(dA-dC) . poly(dG-dT) is reversed to the B-form upon interaction with Nt; Dst-3 also induces this reversal but at higher ligand ratios. The modified B-structure of poly(dA-dT) . poly(dA-dT) in low water activity is efficiently reversed to the B-form by interaction with both Nt and Dst-3.
mesh_terms: D055598:Chemical Phenomena; D002621:Chemistry; D002942:Circular Dichroism; D004247:DNA; D006146:Guanidines; D009429:Netropsin; D009690:Nucleic Acid Conformation; D009994:Osmolar Concentration; D011067:Poly dA-dT / Q000031:analogs & derivatives; D011089:Polydeoxyribonucleotides; D014867:Water
chemical_list: D006146:Guanidines; D011089:Polydeoxyribonucleotides; D014867:Water; D011067:Poly dA-dT; C019530:poly(dC-dG); C033927:poly(dA-dC).poly(dG-dT); D009429:Netropsin; D004247:DNA