The counterions of arginine amino acids impact efficacy and solution properties of the antimicrobial peptide Ac-RRWWRF-NH2

COLL 134

Alicyn M. Rhoades, alicyn.haney@usm.edu, School of Polymers and High Performance Materials, The University of Southern Mississippi, 118 College Drive, #10076, Hattiesburg, MS 39406, Douglas A. Wicks, Douglas.Wicks@usm.edu, University of Southern Mississippi, 39406, and John S. Williamson, mcjsw@olemiss.edu, Department of Medicinal Chemistry, University of Mississippi, School of Pharmacy, Faser 415W, University, MS 38677.
Antimicrobial peptides are characteristically amphiphilic in nature, containing both hydrophobic and cationic residues. The action of the cationic side groups with bacteria membranes is known to be important. However, the impact of the chemical nature of the counterion associated with these cationic residues is not well understood or thoroughly addressed in the literature. We have synthesized both the chloride and the trifloro acetic (TFA) acid salts of the antimicrobial peptide Ac-RRWWRF-NH2. The peptides were tested for antimicrobial efficacy in several different buffer solutions. They were also tested solution and antimicrobial properties when added to 1% solutions of hydroxyethyl cellulose. Evaluation of the antimicrobial efficacy of these peptides reveals this property is influenced by the nature of the counterion. Peptide chloride salts were typically twice as potent as the TFA peptide salts. The location of the peptide within hydroxyethyl cellulose solutions was determined using fluorescence quenching of the tryptophan side chains.
 

Structure, Interactions and Reactivity at Microbial Surfaces
8:30 AM-12:00 PM, Monday, 11 September 2006 Sir Francis Drake -- Windsor Room, Oral

Division of Colloid & Surface Chemistry

The 232nd ACS National Meeting, San Francisco, CA, September 10-14, 2006