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A Helical Region on Human Lactoferrin

Its Role in Antibacterial Pathogenesis
  • D. S. Chapple
  • C. L. Joannou
  • D. J. Mason
  • J. K. Shergill
  • E. W. Odell
  • V. Gant
  • R. W. Evans
Part of the Advances in Experimental Medicine and Biology book series (AEMB, volume 443)

Summary

Human lactoferrin contains a 47 amino acid peptide, named lactoferricin H, which is thought to be responsible for its antimicrobial activity. Lactoferricin includes a loop region, which resides on the outer surface of the N-lobe of lactoferrin, adopting an alpha helix with a hydrophobic tail. Peptides have been synthesised corresponding to the highly charged alpha helix (HLP 2) and hydrophobic tail region (HLP 5). HLP 2 has potent antibacterial activity whereas HLP 5 had no activity. To investigate the relationship between structure and function of HLP 2, HLP 6 was synthesised with a proline replacing methionine. This substitution was predicted to disrupt the helical region of the peptide and the orientation of the positively charged residues. Antibacterial activity was significantly reduced when tested against Escherichia coli serotype 0111, NCTC 8007. The mode of action of HLP 2 against the bacterial membrane was investigated by flow cytometric analysis, using Escherichia coli, NCTC 8007. Membrane potential and integrity were monitored using the fluorescent probes, bis 1,3-(dibutylbarbituric acid) trimethine oxonol and propidium iodide respectively. HLP 2 caused complete loss of membrane potential and integrity, with irreversible damage to the cell as shown by rapid loss of viability. We conclude that HLP 2 causes membrane disruption and that helicity is an important factor for antibacterial activity.

Keywords

Antibacterial Activity Propidium Iodide Human Milk Amino Acid Peptide Barbituric Acid 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer Science+Business Media New York 1998

Authors and Affiliations

  • D. S. Chapple
    • 1
    • 2
    • 3
  • C. L. Joannou
    • 1
  • D. J. Mason
    • 3
  • J. K. Shergill
    • 1
  • E. W. Odell
    • 2
  • V. Gant
    • 3
  • R. W. Evans
    • 1
  1. 1.Division of Biochemistry and Molecular BiologyUnited Medical and Dental Schools of Guy’s and St Thomas’s Hospitals Guys Hospital Medical SchoolLondonUK
  2. 2.Department of Oral Medicine and PathologyUnited Medical and Dental Schools of Guy’s and St Thomas’s Hospitals Guys TowerLondonUK
  3. 3.Division of Infectious Diseases United Medical and Dental Schools of Guy’s and St Thomas’s HospitalsSt Thomas’s HospitalLondonUK

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