Comparison of the conformation and electrostatic surface properties of magainin peptides bound to sodium dodecyl sulfate and dodecylphosphocholine micelles

Abstract

The role played by noncovalent interactions in inducing a stable secondary structure onto the sodium dodecyl sulfate (SDS) and dodecylphosphocholine (DPC) micelle-bound conformations of (Ala(8,13,18))magainin 2 amide and the DPC micelle bound conformation of magainin 1 were determined. Two-dimensional NMR and molecular modeling investigations indicated that (Ala(8,13,18))magainin 2 amide bound to DPC micelles adopts a alpha-helical secondary structure involving residues 2-16. The four C-terminal residues converge to a lose beta-turn structure. (Ala(8,13,18))magainin 2 amide bound to SDS miscelles adopts a alpha-helical secondary structure involving residues 7-18. The C- and N-terminal residues exhibited a great deal of conformational flexibility. Magainin 1 bound to DPC micelles adopts a alpha-helical secondary structure involving residues 4-19. The C-terminal residues converge to a lose beta-turn structure. The results of this investigation indicate hydrophobic interactions are the major contributors to stabilizing the induced helical structure of the micelle-bound peptides. Electrostatic interactions between the polar head groups of the micelle and the cationic side chains of the peptides define the positions along the peptide backbone where the helical structures begin and end.

Enzymatic Characterization and Homology Model of a Catalytically Active Recombinant West Nile Virus NS3 Protease

“…Secondary structure predictions were conducted using web-based PsiPred prediction for each of the three NS3 protease sequences (19). Electrostatic potential mapping was performed on the WNV NS3 protease model using the Delphi module in InsightII (20). A four-residue P3-P1Ј substrate (Thr-Lys-Arg-Gly) was docked into the active site of a homology model of the WNV NS3 protease using GOLD v2.1 (21).…”

Site-directed Mutagenesis and Kinetic Studies of the West Nile Virus NS3 Protease Identify Key Enzyme-Substrate Interactions

“…Secondary structure predictions were conducted using the web-based PsiPred prediction for each of the three NS3 protease sequences (33). Electrostatic potential mapping was performed on the WNV NS3 protease model using the Delphi module in InsightII (34). A four residue P3-P1Ј substrate based on the NS4B-NS5 cleavage site (Leu-Lys-Arg-Gly) was docked into the active site of a homology model of the WNV NS3 protease using GOLD, version 2.1 (35).…”

Structure and Function of Membrane-Lytic Peptides

“…Prime examples for this type of conformational adaptations are melittin, cecropins, or the magainin antibiotic peptides, which exhibit random coil conformations in aqueous solution, and three-dimensional folds in membranes or in membrane-like environments (reviewed in Dempsey, 1990;Sansom et al, 1991;Bechinger, 1999;Hicks et al, 2003). The 26 amino acid amphipathic peptide melittin consists of hydrophobic amino acids at its N-terminus and central region, a proline in the middle of the sequence, a lysine at position 7, and an accumulation of positive charges at its C-terminus (Table, Figure 1a).…”