Polyamine induced Z-conformation of native calf thymus DNA.

Conformational isomerization of native calf thymus DNA under the influence of spermine, spermidine and putrescine was monitored by UV absorption and immunospecific anti-Z-DNA antibodies. Immunological data indicated increased binding of anti-Z-DNA antibodies to polyamine-perturbed conformations of native DNA and double stranded poly(dG-dC). In the absence of polyamines, anti-Z-DNA antibodies did not bind to either polymers. Analysis of UV absorption studies indicates a left handed conformation of nDNA in the presence of polyamines. Moreover, we observed total aggregation of DNA in the presence of spermine on prolongued incubation. These perturbations in conformation were dependent on polyamine concentration. The results clearly suggest that certain regions of nDNA are sensitive to elevated levels of polyamines and are capable of undergoing B-->Z transition.