Document Detail

Differential binding of L- vs. D-isomers of cationic antimicrobial peptides to the biofilm exopolysaccharide alginate.
MedLine Citation:
PMID:  23458077     Owner:  NLM     Status:  Publisher    
Alginate is a biofilm exopolysaccharide secreted by the opportunistic pathogen Pseudomonas aeruginosa that acts to prevent the diffusion of antibiotics toward the bacterial cell membrane. Cationic antimicrobial peptides (CAPs) have been increasingly recognized as a viable alternative for prospective antimicrobial agents. The D-isomer chiral counterparts of active L-isomer CAPs tend to show slightly greater antimicrobial activities because bacteria lack proteases to hydrolyze the unnatural D-isomers. Using an enantiomeric pair of synthetic CAPs designed in our laboratory (L-4Leu in the sequence KKKKKKALFALWLAFLA-NH2 and its D-analog D-4Leu), we studied the binding and interactions of L- vs. D-isomers of CAPs with alginate using circular dichroism and Raman spectroscopic techniques. We found that the peptide D-4Leu underwent a more rapid structural transition over time from an initial alginate-inducedα-helical conformation to a less solubleβ-sheet conformation than L-4Leu, indicating that the D-isomer of this peptide has a relatively greater affinityfor alginate. Through Raman spectroscopy it was observed that Raman modes at 1297 cm-1 and 1453 cm-1wavenumbers were found to differ between the spectra obtained from the insoluble complexes formed between L-4Leu vs. D-4Leu and alginate. These modes were tentatively assigned to CH, and CH3 deformation modes, respectively. Our findings reveal previously undetected subtleties in the binding of this diastereomeric pair of peptides in the microenvironment of abiofilm exopolysaccharide, and provide guidelines for future development of antimicrobial peptides.
Lois M Yin; Soyoung Lee; Jacky S W Mak; Amr S Helmy; Charles M Deber
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2013-2-27
Journal Detail:
Title:  Protein and peptide letters     Volume:  -     ISSN:  1875-5305     ISO Abbreviation:  Protein Pept. Lett.     Publication Date:  2013 Feb 
Date Detail:
Created Date:  2013-3-5     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9441434     Medline TA:  Protein Pept Lett     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Division of Molecular Structure & Function, Research Institute, Hospital for Sick Children, Toronto M5G 1X8.
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