Fluorescence and ESR study of the interaction between the antimicrobial peptide indolicidin and its N-terminally labeled TOAC analogue and model membranes

摘要

The recent years have witnessed a rapid increase in the emergence of microbes resistant to conventionally used antibiotics.To treat infections caused by multi-drug resistant microorganisms,search for new antibiotics has become inevitable and urgent.Indolicidin(ILPWKWPWWPWRR-NH2,IND)a cationic antimicrobial peptide from cytoplasmic granules of bovine neutrophils has a broad spectrum of antimicrobial activity.It is thought to disrupt membranes via pore formation.However,its detailed molecular mechanism of action is still unknown.The current study aims at providing further insight into the molecular aspects of this process.Among the spectroscopic techniques available for the investigation of the conformation and dynamics of peptides,spin labeling electron paramagnetic resonance(EPR)has been used to a considerable extent.This approach enjoyed notable expansion following the introduction of the paramagnetic amino acid 2,2,6,6-tetramethylpiperidine-l-oxyl-4-amino-4-carboxylic acid(TOAC),which allows the incorporation of the spin probe into the peptide via a peptide bond.Following these early studies,TOAC was used in the investigation of many natural and synthetic peptides.