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Anti-microbial activity of human CAP18 peptides
J W Larrick1, M Hirata, J Zhong
1Palo Alto Institute of Molecular Medicine, Mountain View, CA 94043, USA.
Summary
Human CAP18 peptides show broad antimicrobial activity against Gram-positive and Gram-negative bacteria. These findings suggest potential therapeutic applications for bacterial sepsis treatment.
Area of Science:
- Antimicrobial Peptides
- Molecular Biology
- Immunology
Background:
- CAP18, a protein from rabbit leukocytes, exhibits Lipopolysaccharide (LPS) binding and antimicrobial properties.
- The C-terminal domain (amino acids 106-142) of rabbit CAP18 is responsible for its LPS-binding and antimicrobial activity.
- The homologous human CAP18 domain (huCAP18(104-140)) was identified from cloned human CAP18 cDNA.
Purpose of the Study:
- To assess the antimicrobial efficacy of C-terminal peptides derived from human CAP18.
- To investigate the activity spectrum of synthetic human CAP18(104-140) against various bacterial strains.
Main Methods:
- Synthesis of the human CAP18(104-140) peptide.
- Evaluation of antimicrobial activity against a panel of Gram-negative and Gram-positive bacteria.
- Testing of peptide activity in serum-containing environments.
Main Results:
- Synthetic human CAP18(104-140) demonstrated broad-spectrum antimicrobial activity, with IC50 values ranging from 0.5-5 µg/ml for Gram-negative bacteria and 2.5 µg/ml for Gram-positive bacteria.
- Susceptible bacterial strains included Staphylococcus aureus, Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa, and Salmonella typhimurium.
- A truncated 32-amino acid peptide showed enhanced activity, and CAP18(104-140) remained active in serum, unlike other granulocyte-derived antimicrobial peptides.
Conclusions:
- Human CAP18(104-140) and its derivatives possess significant antimicrobial properties.
- These peptides show therapeutic potential for treating bacterial infections, including bacterial sepsis.