title: Solution structure of pardaxin P-2.
abstract: Pardaxin is a mucosal secretion of the Pacific sole Pardachirus pavoninus that exhibits unusual shark repellent and surfactant properties [Thompson, S. A., Tachibana, K., Nakanishi, K., & Kubota, I. (1986) Science 233, 341-343]. This 33 amino acid polypeptide folds into ordered structures in trifluoroethanol-water solution and in micelles but adopts a random-coiled structure in water solution. The complete proton NMR spectrum of pardaxin P-2 has been assigned in CF3CD2OD/H2O (1:1) solution, and the three-dimensional structure has been elucidated with distance restrained molecular dynamics calculations. It is demonstrated that peptide segments within the 7-11 and 14-26 residue stretches are helical while residues at the C- and N-terminus exist predominantly in extended conformations in solution. The dipeptide 12-13 segment connecting the two helices exists as a bend or a hinge allowing the two helices to be oriented in a L-shaped configuration. These studies establish that pardaxin P-2 adopts a novel amphiphilic helix (7-11)-bend (12-13)-helix (14-26) motif with Pro-13 forming the focal point of the turn or bend between the two helices.
authors.affiliation: Department of Biochemistry and Molecular Biophysics, College of Physicians and Surgeons, Columbia University, New York, New York 10032.
authors.forename: M G
authors.initials: MG
authors.lastname: Zagorski
authors.forename: D G
authors.initials: DG
authors.lastname: Norman
authors.forename: C J
authors.initials: CJ
authors.lastname: Barrow
authors.forename: T
authors.initials: T
authors.lastname: Iwashita
authors.forename: K
authors.initials: K
authors.lastname: Tachibana
authors.forename: D J
authors.initials: DJ
authors.lastname: Patel
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003198:Computer Simulation; D005397:Fish Venoms / Q000138:chemical synthesis / Q000737:chemistry*; D005412:Flatfishes; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D012996:Solutions
chemical_list: D005397:Fish Venoms; D012996:Solutions; C017603:pardaxin