C-Terminal Modification and Multimerization Increase the Efficacy of a Proline-Rich Antimicrobial Peptide

Wenyi Li, Neil M. O'Brien-Simpson, Shenggen Yao, Julien Tailhades, Eric C. Reynolds, Raymond M. Dawson, Laszlo Otvos, Jr., Mohammed Akhter Hossain, Frances Separovic, John D. Wade

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8 Citations (Scopus)


Two series of branched tetramers of the proline-rich antimicrobial peptide (PrAMP), Chex1-Arg20, were prepared to improve antibacterial selectivity and potency against a panel of Gram-negative nosocomial pathogens including Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumannii and Pseudomonas aeruginosa. First, tetramerization was achieved by dithiomaleimide (DTM) conjugation of two C-terminal-cysteine bearing dimers that also incorporated C-terminal peptide chemical modification. DTM-linked tetrameric peptides containing a C-terminal hydrazide moiety on each dimer exhibited highly potent activities in the minimum inhibitory concentration (MIC) range of 0.49–2.33 μm. A second series of tetrameric analogues with C-terminal hydrazide modification was prepared by using alternative conjugation linkers including trans-1,4-dibromo-2-butene, α,α’-dibromo-p-xylene, or 6-bismaleimidohexane to determine the effect of length on activity. Each displayed potent and broadened activity against Gram-negative nosocomial pathogens, particularly the butene-linked tetrameric hydrazide. Remarkably, the greatest MIC activity is against P. aeruginosa (0.77 μm/8 μg mL−1) where the monomer is inactive. None of these peptides showed any cytotoxicity to mammalian cells up to 25 times the MIC. A diffusion NMR study of the tetrameric hydrazides showed that the more active antibacterial analogues were those with a more compact structure having smaller hydrodynamic radii. The results show that C-terminal PrAMP hydrazidation together with its rational tetramerization is an effective means for increasing both diversity and potency of PrAMP action.

Original languageEnglish
Pages (from-to)390-396
Number of pages7
JournalChemistry - A European Journal
Issue number2
Publication statusPublished - 5 Jan 2017
Externally publishedYes


  • compacted structure
  • conjugation
  • expanded activity
  • peptides
  • tetramers

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