title: Design of synthetic bactericidal peptides derived from the bactericidal domain P(18-39) of aprotinin.
abstract: A bactericidal domain, P(18-39), of the proteinase inhibitor aprotinin, possesses the structural feature of two antiparallel beta-sheets connected by a short turn. In order to understand the structural requirements for antibacterial activity, two peptides, each having the sequence corresponding to a single beta-sheet structure of P(18-39), were synthesized and their antibacterial properties investigated. One peptide, P(18-28), with the sequence IIRYFYNAKAG, was active against almost all the bacterial strains investigated. However, the bactericidal activity of P(18-28) was reduced compared to the parent molecule, P(18-39). The other peptide, P(29-39), with the sequence LCQTFVYGGCR, was only weakly bactericidal against Pseudomonas aeruginosa. A peptide, P(18-26), devoid of the C-terminus dipeptide Ala-Gly of P(18-28), retained the bactericidal activity of P(18-28) against most of the bacterial strains investigated. Only Klebsiella pneumoniae, P. aeruginosa and Staphylococcus aureus were resistant to P(18-26). Replacement of lysine 26 by arginine in P(18-26) (IIRYFYNAR) improved the bactericidal activity. The retropeptide, RANYFYRII, retained the antibacterial activity of IIRYFYNAR toward Gram-negative bacteria, but it was less active against Gram-positive bacteria. The random peptide, IANRIYRYF, was as bactericidal as IIRYFYNAR. Moreover, the random peptide possessed, in contrast to IIRYFYNAR, a strong antifungal activity against Candida albicans. Elimination of the N-hydrophobic terminal Ile-Ile from P(18-26) (RYFYNAK) strongly reduced the bactericidal potency of the peptide. Attaching the hydrophobic peptide, FFVAP, to the C-terminal of P(18-26) (IIRYFYNAKFFVAP) increased the bactericidal potency of the peptides considerably. We concluded that the order of the amino acids in the sequence of the peptides is not, per se, a critical feature for bactericidal activity. Hydrophobic interaction between peptide and bacterial membrane is probably the most important feature involved in the bactericidal mechanism of the antibiotic peptides.
authors.affiliation: Institute of Veterinary Physiology, Division of Applied Physiology, University of Zürich, CH-8057, Zürich, Switzerland. pella@vetphys.unizh.ch
authors.forename: A
authors.initials: A
authors.lastname: Pellegrini
authors.forename: R
authors.initials: R
authors.lastname: von Fellenberg
mesh_terms: D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents / Q000737:chemistry* / Q000494:pharmacology; D007611:Aprotinin / Q000031:analogs & derivatives / Q000737:chemistry*; D001412:Bacillus subtilis / Q000187:drug effects; D002176:Candida albicans / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D015195:Drug Design; D004926:Escherichia coli / Q000187:drug effects; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000494:pharmacology; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology; D015842:Serine Proteinase Inhibitors / Q000737:chemistry*
chemical_list: D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents; D010446:Peptide Fragments; D010455:Peptides; D015842:Serine Proteinase Inhibitors; D007611:Aprotinin