N-Terminal analogs of cecropin A: synthesis, antibacterial activity, and conformational properties

Authors:
  • DADavid Andreu
    David Andreu
  • RMR. B. Merrifield
    R. B. Merrifield
  • HSHaakan Steiner
    Haakan Steiner
  • HBHans G. Boman
    Hans G. Boman
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Abstract
Six analogues of the 37-residue antibacterial peptide cecropin A were synthesized by the solid-phase method: cecropin A-(2-37), [Glu2]cecropin A, [Pro4]cecropin A, [Glu6]cecropin A, [Leu6]cecropin A, and [Pro8]cecropin A. Their antibacterial activities against four test organisms were determined and related to conformational changes observed in their CD spectra and were discussed on the basis of a previously proposed amphipathic alpha-helix model. An aromatic residue in position 2 was shown to be important for activity against all tested bacteria. The highly alpha-helical 1-11 region of cecropin A did not appear to play a significant role in its activity against Escherichia coli but was clearly involved in its interaction against Pseudomonas aeruginosa, Bacillus megaterium, and Micrococcus luteus.