title: Simulations of conformers of tuftsin and a cyclic tuftsin analog.
abstract: The conformational properties of the configurational isomers of tuftsin, a linear tetrapeptide with the sequence Thr-Lys-Pro-Arg, were investigated with six 1 ns molecular dynamics simulations in explicit water and in a 1.0 m NaCl solution. The average conformation of the cis isomer is a type VI beta-turn. Our results indicate that water-peptide hydrogen bonding, in addition to intramolecular hydrogen bonds, stabilizes the cis conformer. The trans isomer is neither a beta- nor a gamma-turn. Results are compared with parallel studies on a cyclic analog of tuftsin, cyclo(Thr-Lys-Pro-Arg-Gly). The addition of salt does, not influence the backbone conformation of the peptide. Differences between the structures are confined to the side-chain orientations of the Lys and Arg residues.
authors.affiliation: Department of Chemistry, University of Houston, Texas, USA.
authors.forename: C V
authors.initials: CV
authors.lastname: Valdeavella
authors.forename: H D
authors.initials: HD
authors.lastname: Blatt
authors.forename: B M
authors.initials: BM
authors.lastname: Pettitt
mesh_terms: D000595:Amino Acid Sequence; D003500:Cyclization; D004563:Electrochemistry; D006860:Hydrogen Bonding; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D012965:Sodium Chloride; D012996:Solutions; D014405:Tuftsin / Q000737:chemistry*; D014867:Water
chemical_list: D012996:Solutions; D014867:Water; D012965:Sodium Chloride; D014405:Tuftsin