[Interaction of a synthetic peptide, containing a part of the DNA-binding domain of the v-jun transcription activator, with DNA].

Synthesis and DNA-binding activity of the synthetic 26-residue peptide, containing in two copies a part of the DNA-binding domain of the transcription activator v-Jun, are reported. Using CD spectroscopy, it has been shown that the peptide exists in a random coil conformation in aqueous solution, but assumes partially an alpha-helical conformation in the presence of 20% trifluoroethanol. The percentage of alpha-helix is increased in the presence of 40% trifluoroethanol up to approximately 80%. It has been shown that the peptide forms two types of complexes with DNA. The first type of complexes saturates when one peptide molecule occupies six base pairs. At further increase of molar peptide to DNA ratio the binding became a cooperative process. The binding approaches saturation when one peptide molecule is bound approximately to four DNA base pairs. The binding constant of the monomer peptide complex with DNA has been estimated to be approximately 1.10(5) M-1 in the presence of 0.2 M NaCl. The peptide binds more strongly to poly(dG).poly(dC) and poly(dA).poly(dT) than to poly[d(GC)].poly[d(GC)]. We found that the DNA minor groove-binding antibiotic distamycin A competes effectively with the peptide for binding to poly(dA).poly(dT).