title: Interactions that regulate the helical fold in proteins.
abstract: Several factors that may contribute to the stabilization of the helical structure in proteins, detected in studies made on short synthetic peptides, have been reported. Some of them are: presence of alanine or leucine, ionic-pair bonding, stabilization of the helical dipole moment by appropriate charges at the helix N- and C-caps, and aromatic interactions of amino acids located at positions i, i + 4. An analysis of 54 helical structures from 12 proteins showed that all these stabilizing factors were also present in proteins, but the influence of any of them had a different weight, according to the distribution of the hydrophobic and hydrophilic amino acid residues in the helical sequence. The role of non-sequence depending interactions in helical stability, such as presence of disulfide bridges, or bonding of helical residues to substrate and/or cofactors, was also analysed.
authors.affiliation: Departamento de Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Chile.
authors.forename: H
authors.initials: H
authors.lastname: Cid
authors.forename: F
authors.initials: F
authors.lastname: Gazitua
authors.forename: M
authors.initials: M
authors.lastname: Bunster
mesh_terms: D000409:Alanine / Q000502:physiology*; D000596:Amino Acids / Q000502:physiology*; D004795:Enzyme Stability / Q000502:physiology*; D007930:Leucine / Q000502:physiology*; D009113:Muramidase / Q000648:ultrastructure*; D010187:Pancreatic Hormones / Q000502:physiology*; D017433:Protein Structure, Secondary
chemical_list: D000596:Amino Acids; D010187:Pancreatic Hormones; D009113:Muramidase; D007930:Leucine; D000409:Alanine