Effect of Fatty Acid Conjugation on Antimicrobial Peptide Activity

摘要

Two peptides, YGAAKKAAKAA2 (AKK), and YGAKAKAAKA2 (KAK) were conjugated to fatty acids and tested for the effect on their structure, antibacterial activity, and eukaryotic cell toxicity. In the presence of bacteria-mimicking phospholipid vesicles fatty acid conjugates of the amphipathic peptide, AKK, show a larger change in helical structure than either of the unmodified peptides or the conjugate of the nonamphipathic peptide, KAK. The induction of helicity corresponds to a significant improvement in antimicrobial activity as measured by a minimum bactericidal concentration test. Lengthening the fatty acid conjugate improves the antimicrobial activity of AKK as long as the peptide has less than 16 carbons. Peptide AKK conjugated to fatty acids with more than 16 carbons show no antimicrobial activity. Investigation of peptide and peptide amphiphile structure in the presence of red blood cell-mimicking phospholipid vesicles shows that neither the peptides, nor the fatty acid conjugated peptides have any significant helical structure. Neither the peptides nor their lauric acid conjugates showed significant hemolytic activity.