Cationic comb-type copolymer as an artificial chaperone

Abstract

Accurate folding of biopolymers and assembly of complexes containing these molecules are essential for biological activities. We designed cationic comb-type copolymers that act as an artificial chaperone to assist in the folding of biopolymers such as nucleic acids and peptides. The copolymers consist of a polycation backbone grafted with a high density of hydrophilic chains that allow the formation of soluble and soft interpolyelectrolyte complexes between the copolymer and oppositely charged biopolymers. The copolymers can chaperone DNA assembly into duplex, triplex, and quadruplex structures and accelerate strand exchange reactions while stabilizing DNA complexes. This chaperone activity of the copolymer is useful in nucleic acid-based nanotechnological applications such as DNA nanomachines, DNA logic gates, and DNA enzymes. The cationic comb-type copolymers also assisted in the folding of functional peptides. The basic E5 peptide folds into an alpha-helical structure and exhibits a stronger membrane-disrupting activity in the presence of the copolymer than in its absence. The cationic comb-type copolymers, as an artificial chaperone, were shown to be beneficial for enhancing the functions and facilitating the application of biopolymers in nanotechnology and medicine. The cationic comb-type copolymers, which consisted of a polycation backbone grafted with high density of hydrophilic chains, form soluble and soft interpolyelectrolyte complexes with biopolymers and act as an artificial chaperone to assist in the folding of nucleic acids and peptides. The copolymers stabilize DNA duplex, triplex, and quadruplex structures and accelerate strand exchange reactions as well as assist in the folding of functional peptides into the active conformation.