title: Selective aromatic interactions in beta-hairpin peptides.
abstract: To probe the selectivity possible in hydrophobic clusters, we have compared the cross-strand interactions of phenylalanine (Phe) and cyclohexylalanine (Cha) in a beta-hairpin peptide. We have found a preference for self-association among the aromatic residues, which provides 0.55 kcal/mol in stability relative to Cha-Cha cross-strand pair. NMR analysis of the Phe-Phe cross-strand pair indicates that it interacts in an edge-face interaction, despite the fact that it is highly solvent-exposed. The interaction geometry as well as the enthalpic and entropic values for the peptide containing the Phe-Phe cross-strand pair suggest that the preference for self-association arises from inherent differences in the nature of aromatic and aliphatic interactions in water.
authors.affiliation: Department of Chemistry, University of North Carolina, Chapel Hill 27599-3290, USA.
authors.forename: Chad D
authors.initials: CD
authors.lastname: Tatko
authors.forename: Marcey L
authors.initials: ML
authors.lastname: Waters
mesh_terms: D010455:Peptides / Q000737:chemistry*; D055672:Static Electricity; D013816:Thermodynamics
chemical_list: D010455:Peptides