Electron microscopy of DNA complexes with synthetic oligopeptides

Electron microscopical data is presented on the varying morphology of the complexes formed between DNA and a number of synthetic β-oligopeptides. In general, these peptides produce DNA compaction or condensation, resulting in two main types of complexes: toroids and rods. By controlling the ratio of peptide to DNA, interpretations of the possible packing of DNA within the various compact particles are advanced. Some understanding of the mechanism of peptide-induced DNA compaction in vitro may be of significance in relation to DNA condensation and the discrimination of gene domains in vivo.