Conformation and self-association of a hybrid peptide of cecropin A and melittin with improved antibiotic activity

Imma Fernández, Josep Ubach, M. Fuxreiter, José Manuel Andreu, David Andreu, Miquel Pons

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

A 15-residue hybrid peptide containing residues 1-7 from cecropin A and residues 2-9 from melittin, CA-(1-7)M(2-9), is a potent antibiotic with broader activity than cecropin A, but without the cytotoxic character of melittin. The conformational behaviour of CA(1-7) M(2-9) including the formation of multimeric species in solution has been investigated by circular dichroism, ultracentrifugation, electrospray mass spectrometry, NMR and energy calculations. Addition of hexafluoroisopropanol or liposomes causes the appearance of a CD spectrum characteristic of a helical structure that changes with pH, buffer and peptide concentration. The concentration dependence is atypical, as the ellipticity at 222 nm decreases with peptide concentration and is not correlated with a corresponding decrease in helix content as measured from the NMR spectra. The presence of aggregated structures is demonstrated by ultracentrifugation and ES-MS experiments, which also provide an indication of the stoichiometry. Long-range NOEs suggest a model of aggregation with neighbouring molecules packed antiparallel. Aggregation causes very slow proton-deuterium exchange in some amide protons in the C-terminal region and provides a method for estimating a very large association constant (ca. 10 6M-1) as well as the stoichiometry of the aggregates. The tendency to aggregate seems to be an inherited feature from melittin and may enhance the antibiotic activity either by facilitating the incorporation of the peptide into the membrane in large quantities or by promoting the disruption of the membrane.

Original languageEnglish
Pages (from-to)838-846
Number of pages9
JournalChemistry - A European Journal
Volume2
Issue number7
DOIs
Publication statusPublished - 1996

Fingerprint

Melitten
Antibiotics
Peptides
Conformations
Association reactions
Anti-Bacterial Agents
Stoichiometry
Protons
Agglomeration
Nuclear magnetic resonance
Membranes
Liposomes
Deuterium
Dichroism
Amides
Mass spectrometry
Ion exchange
Buffers
Molecules
cecropin A

Keywords

  • Aggregation
  • Antibiotics
  • Circular dichroism
  • Helices
  • Peptides

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

Conformation and self-association of a hybrid peptide of cecropin A and melittin with improved antibiotic activity. / Fernández, Imma; Ubach, Josep; Fuxreiter, M.; Andreu, José Manuel; Andreu, David; Pons, Miquel.

In: Chemistry - A European Journal, Vol. 2, No. 7, 1996, p. 838-846.

Research output: Contribution to journalArticle

Fernández, Imma ; Ubach, Josep ; Fuxreiter, M. ; Andreu, José Manuel ; Andreu, David ; Pons, Miquel. / Conformation and self-association of a hybrid peptide of cecropin A and melittin with improved antibiotic activity. In: Chemistry - A European Journal. 1996 ; Vol. 2, No. 7. pp. 838-846.
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