B-->Z transition in native calf thymus DNA depends on its microenvironment.

Z-DNA forming potentiality of native calf thymus DNA was investigated under varying experimental conditions. Ethidium intercalation and Scatchard analysis data showed decreased binding of ethidium to nDNA at 4.27 M NaCl. A comparison of ethidium binding to DNA in low and high salt indicated the formation of Z-DNA. The binding of monoclonal anti-Z-DNA antibody to nDNA fragments brominated in high salt reiterated the transition of B-->Z conformation.