Basic polypeptides as histone models. Synthesis, conformation, and interaction with DNA of statistical copolymers (Lys^<i>x</i>,Ala^<i>y</i>)_<i>n</i>

Abstract

Abstract Statistical copolymers (Lys x ,Ala y ) n were synthesized by copolymerization of N ‐carboxyanhydrides of L ‐amino acids. The conformation of copolymers in aqueous solutions was investigated using circular dichroism (CD). Calculations based on the CD data showed that polymers (Lys x ,Ala y ) n can exhibit a random conformation, an α‐helix, and a β‐structure in various ratios. CD spectra of complexes of copolymers with DNA prepared by gradual dialysis from a high ionic strength to 0.15 M NaCl can be correlated with the copolymer conformation in medium and high ionic strength. For copolymers forming an α‐helix and β‐structure, these spectra show resemblance with similar spectra of complexes of those histones that are able to exhibit ordered conformations.