title: C11/C9 helices in crystals of αβ hybrid peptides and switching structures between helix types by variation in the α-residue.
abstract: Close-packed helices with mixed hydrogen bond directionality are unprecedented in the structural chemistry of α-polypeptides. While NMR studies in solution state provide strong evidence for the occurrence of mixed helices in (ββ)n and (αβ)n sequences, limited information is currently available in crystals. The peptide structures presented show the occurrence of C11/C9 helices in (αβ)n peptides. Transitions between C11 and C11/C9 helices are observed upon varying the α-amino acid residue.
authors.affiliation: Molecular Biophysics Unit, Indian Institute of Science , Bangalore 560012, India.
authors.forename: Krishnayan
authors.initials: K
authors.lastname: Basuroy
authors.forename: Vasantham
authors.initials: V
authors.lastname: Karuppiah
authors.forename: Padmanabhan
authors.initials: P
authors.lastname: Balaram
mesh_terms: D000596:Amino Acids / Q000737:chemistry; D006860:Hydrogen Bonding; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D010455:Peptides / Q000737:chemistry*; D017433:Protein Structure, Secondary
chemical_list: D000596:Amino Acids; D010455:Peptides