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Antimicrobial Peptides Produced by Selective Pressure Incorporation of Non-canonical Amino Acids
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Antimicrobial peptides derived from heme-containing proteins: hemocidins

P Mak1, K Wójcik, J Silberring

  • 1Institute of Molecular Biology, Jagiellonian University, Mickiewicza 3, 31-120 Kraków, Poland.

Antonie Van Leeuwenhoek
|June 11, 2004
PubMed

Insights

Apohemoproteins like myoglobin and cytochrome c, when stripped of heme, exhibit broad-spectrum antimicrobial activity. Specific peptide fragments retain this activity, suggesting a novel class of antimicrobials called hemocidins.

Area of Science:

  • Biochemistry
  • Microbiology
  • Biophysics

Background:

  • Heme-containing proteins, such as hemoglobin, myoglobin, and cytochrome c, are crucial in biological systems.
  • While intact proteins are generally not antimicrobial, their modified forms may possess such activities.

Purpose of the Study:

  • To investigate the antimicrobial potential of heme-deprived hemoproteins and their peptide fragments.
  • To characterize the mechanism of action and specificity of these antimicrobial peptides.

Main Methods:

  • Heme removal from myoglobin, hemoglobin, and cytochrome c.
  • Enzymatic digestion of apohemoproteins to generate peptide fragments.
  • Assessment of microbicidal activity against various microorganisms.
  • Analysis of membrane permeabilization, cation sensitivity, and cytotoxicity assays.

Main Results:

  • Heme-deprived hemoproteins (apohemoproteins) showed microbicidal activity against a broad spectrum of microorganisms at micromolar concentrations.
  • Antibacterial activity was retained in peptides of approximately 50 amino acids but lost upon further fragmentation.
  • The most active apomyoglobin fragment (56-131) permeabilized E. coli membranes in a salt- and cation-dependent manner.
  • No lipopolysaccharide binding or hemolytic activity was observed, though slight cytotoxicity to mammalian cells occurred.

Conclusions:

  • Apohemoproteins and their derived peptides possess significant antimicrobial properties, distinct from intact proteins.
  • The mechanism involves membrane permeabilization, potentially via a 'carpet-like' mechanism facilitated by alpha-helical structures.
  • These findings suggest a new class of antimicrobial peptides, termed 'hemocidins'.

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