Soft Polymer Complexes to Engineer Biopolymer Assemblies and Functions

Abstract

Correct folding and assembling are essential for biopolymers to exhibit their inherent biological activities. We have designed ionic comb-type copolymers consisting of a polyion backbone and hydrophilic graft chains to engineer folding and assembling of biopolymers, such as DNA and peptides, having opposite ionic charges. The cationic copolymer formed soluble and soft inter-polyelectrolyte complex (IPEC) with DNA and acidic peptides. The copolymers significantly facilitate nucleic acid assembly including DNA duplex, triplex and quadruplex formations. Activities of functional DNAs such as molecular beacons and DNAzymes were enhanced by the copolymer. The cationic comb-type copolymers also facilitated folding of peptides having anionic charges. E5 peptide, a membrane active peptide, was folded into alpha-helical structure by the added copolymer. The copolymer/peptide mixture showed stronger membrane disrupting activity than peptide alone. Soluble and soft IPECs produced with the ionic comb-type copolymer are promising to improve function and applications of biopolymers.