[Enzyme immunologic method for the study of left-handed DNA]

A brominated poly[d(G-C)].poly[d(G-C)] which forms a stable Z-DNA helix under physiological salt conditions was prepared. The rabbits were immunized with the brominated polynucleotide complexed with methylated bovine serum albumin. Antisera that are highly specific to the Z-DNA were produced: there is practically no interaction between the antisera and the native or denaturated DNA and the B-form of poly[d(G-C)].poly[d(G-C)]. This makes possible their use as reagents for determining the presence of Z-DNA in biological systems. A sensitive enzyme-linked immunosorbent assay (ELISA) that permits detection of 5 ng/ml Z-DNA was developed. This method was used for studying the B-Z transition and for antigenic determinant characterization. It was established, that formaldehyde amino-derivatives interact with the antigenic determinant and prevent the immunochemical assay of Z-DNA. The H1 and H3 histones prevent and and spermine increases the interaction of Z-DNA with antibodies.