Antibody recognition of common epitopes on Z-DNA and native DNA brominated under high salt

Native calf thymus DNA brominated under high salt (4 M NaCl) adopt Z-/analogous conformation as indicated by UV absorption and difference spectra. The bromination of guanine (44%) was twice as effective as cytosine (22%) and induced thermal instability in the modified polymer. The changes are similar to those observed in Z-form of poly(dG.dC).poly(dG.dC). Antibodies were raised in rabbits against these conformationally altered nucleic acids. Both the polymers were highly immunogenic and produced high titer precipitating antibodies which were completely identical in double immunodiffusion. Immunoaffinity purified IgGs showed binding of common conformational epitopes on Z-DNA and brominated DNA. It is evident that on bromination in high salt, regions of native DNA attain Z-/analogous conformation along its strand.