title: Antiparallel Self-Association of a γ,α-Hybrid Peptide: More Relevance of Weak Interactions.
abstract: To learn how a preorganized peptide-based molecular template, together with diverse weak non-covalent interactions, leads to an effective self-association, we investigated the conformational characteristics of a simple γ,α-hybrid model peptide, Boc-γ-Abz-Gly-OMe. The single-crystal X-ray diffraction analysis revealed the existence of a fully extended β-strand-like structure stabilized by two non-conventional C-H⋅⋅⋅O=C intramolecular H-bonds. The 2D (1) H NMR ROESY experiment led us to propose that the flat topology of the urethane-γ-Abz-amide moiety is predominantly preserved in a non-polar environment. The self-association of the energetically more favorable antiparallel β-strand-mimic in solid-state engenders an unusual 'flight of stairs' fabricated through face-to-face and edge-to-edge Ar⋅⋅⋅Ar interactions. In conjunction with FT-IR spectroscopic analysis in chloroform, we highlight that conformationally semi-rigid γ-Abz foldamer in appositely designed peptides may encourage unusual β-strand or β-sheet-like self-association and supramolecular organization stabilized via weak attractive forces.
authors.affiliation: Department of Chemistry, Panjab University, Sector 14, Chandigarh-, 160 014, India.
authors.forename: Paloth
authors.initials: P
authors.lastname: Venugopalan
authors.affiliation: Protein Science & Engineering Division, CSIR-Institute of Microbial Technology, Sector 39-A, Chandigarh-, 160 036, India. kishore@imtech.res.in.
authors.forename: Raghuvansh
authors.initials: R
authors.lastname: Kishore
mesh_terms: D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D008958:Models, Molecular; D010455:Peptides / Q000737:chemistry*; D017433:Protein Structure, Secondary; D066244:Proton Magnetic Resonance Spectroscopy; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D010455:Peptides
keywords: X-ray diffraction; foldamers; peptide design; self-association; weak interactions; β-strand mimics