Conformation of oligonucleotides and nucleic acids modified with 2-aminofluorene or 2-acetylaminofluorene

The first part of this work deals with the thermal stability of oligonucleotides modified with acetylaminofluorene and aminofluorene, respectively. The complementary oligonucleotides d(CGCG), d(CGTACG) and d(AATTGCAATT) have been studied by ultraviolet absorption and circular dichroism. In high salt concentration and at low temperature, the three oligonucleotides form double-stranded helices which have the B-form Substitution of guanine residues in these oligonucleotides by acetylated or deacetylated aminofluorene residues destablizes the B-form and does not induce the transition to the Z-form. The second part of the work deals with the antibodies to Z-DNA. The specificity of these antibodies has been determined by radioimmunoassay. The antibodies react with the Z-form but not with the B-form. Poly(dG-dC).poly(dG-dC) modified by acetylaminofluorene residues is recognized by the antibodies. The antibodies can detect the Z-form in natural DNA as visualized by fluorescent staining of polytene chromosomes from Drosophila melanogaster.