Stabilization of Z-RNA under Physiological Conditions and Recognition by Anti-Z DNA Antibodies.

Abstract : Radioimmunoassay and nitrocellulose filter-binding competition experiments were performed to determine the extent of recognition of Bromine-poly(r(C-G) by anti-Z-DNA antibodies. The polyclonal rabbit anti-Br-poly(d(C-G)igG preparations T4 and Z6 specifically recognize the Z-form of polyR(C-G, although the binding affinities are 10-to 100fold lower for Z-RNA than for various forms of Z-DNA. Competition RIA experiments verify the presence of a Z-DNA like determinant in left handed Br poly R(C-G) at physiological Sodium Chloride concentration. Phosphate buffer or high ionic strength conditions inhibit recognition of Z-RNA by anti Z-DNA IgGs, consistent with recognition of a phosphodiester backbone determinant. In summary, these spectroscopic and immunochemical studies demonstrate that under conditions of conformational stress (i.e. containing brominated nucleosides) left-handed Z-RNA is stable and is specifically recognized by proteins at physiological temperature and ionic strength.