title: A simple gamma-backbone modification preorganizes peptide nucleic acid into a helical structure.
abstract: Peptide nucleic acid (PNA) is a synthetic analogue of DNA and RNA, developed more than a decade ago in which the naturally occurring sugar phosphate backbone has been replaced by the N-(2-aminoethyl) glycine units. Unlike DNA or RNA in the unhybridized state (single strand) which can adopt a helical structure through base-stacking, although highly flexible, PNA does not have a well-defined conformational folding in solution. Herein, we show that a simple backbone modification at the gamma-position of the N-(2-aminoethyl) glycine unit can transform a randomly folded PNA into a helical structure. Spectroscopic studies showed that helical induction occurs in the C- to N-terminal direction and is sterically driven. This finding has important implication not only on the future design of nucleic acid mimics but also on the design of novel materials, where molecular organization and efficient electronic coupling are desired.
authors.affiliation: Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, USA.
authors.forename: Anca
authors.initials: A
authors.lastname: Dragulescu-Andrasi
authors.forename: Srinivas
authors.initials: S
authors.lastname: Rapireddy
authors.forename: Brian M
authors.initials: BM
authors.lastname: Frezza
authors.forename: Chakicherla
authors.initials: C
authors.lastname: Gayathri
authors.forename: Roberto R
authors.initials: RR
authors.lastname: Gil
authors.forename: Danith H
authors.initials: DH
authors.lastname: Ly
mesh_terms: D002942:Circular Dichroism; D019281:Dimerization; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D009690:Nucleic Acid Conformation; D020135:Peptide Nucleic Acids / Q000737:chemistry*; D013696:Temperature
chemical_list: D020135:Peptide Nucleic Acids