Solution structure of a designed amphipathic antimicrobial synthetic peptide, PGAa

Biochem Biophys Res Commun. 2000 Oct 5;276(3):1278-85. doi: 10.1006/bbrc.2000.3587.

Abstract

A designed peptide, PGAa showed an excellent antifungal activity as well as an efficient bactericidal activity toward gram-positive, especially in the pathogenic yeast Candida albicans 28838. The solution structures of PGAa have been determined both in 40% TFE/water solution and DPC micelle by CD and NMR spectroscopy. Based on NOEs, vicinal coupling constants, backbone amide exchange rates, and chemical shift indices, PGAa formed a long amphipathic alpha-helical conformation in both TFE and DPC micelle environments, spanning the residues Ile(2)-Ala(19) in TFE and Lys(5)-Ala(19) in DPC micelle, respectively. Solution structures suggested that the hydrophobic residues would interact with the fatty acyl chains of the lipid bilayer, while the positively charged side-chains exposed to aqueous environments. Therefore, we conclude that the alpha-helical structure as well as the highly amphiphatic nature of PGAa peptide may play a critical role in its antimicrobial activity as well as selectivities in different species.

MeSH terms

  • 1,2-Dipalmitoylphosphatidylcholine / metabolism
  • Amino Acid Sequence
  • Anti-Infective Agents / chemical synthesis
  • Anti-Infective Agents / chemistry*
  • Anti-Infective Agents / metabolism
  • Anti-Infective Agents / pharmacology*
  • Antifungal Agents / chemical synthesis
  • Antifungal Agents / chemistry
  • Antifungal Agents / metabolism
  • Antifungal Agents / pharmacology
  • Antimicrobial Cationic Peptides
  • Candida / drug effects*
  • Candida / growth & development
  • Circular Dichroism
  • Hydrogen Bonding
  • Lipid Bilayers / chemistry
  • Lipid Bilayers / metabolism
  • Micelles
  • Microbial Sensitivity Tests
  • Models, Molecular
  • Molecular Sequence Data
  • Nuclear Magnetic Resonance, Biomolecular
  • Peptides / chemical synthesis
  • Peptides / chemistry*
  • Peptides / metabolism
  • Peptides / pharmacology*
  • Protein Structure, Secondary
  • Solutions
  • Species Specificity
  • Structure-Activity Relationship
  • Trifluoroacetic Acid / metabolism
  • Water / metabolism

Substances

  • Anti-Infective Agents
  • Antifungal Agents
  • Antimicrobial Cationic Peptides
  • Lipid Bilayers
  • Micelles
  • Peptides
  • Solutions
  • antimicrobial peptide, PGAa
  • Water
  • 1,2-Dipalmitoylphosphatidylcholine
  • Trifluoroacetic Acid