Cecropin A
Insect antimicrobial peptide from the cecropia moth that pioneered innate immunity research and inspired peptide antibiotic development.
Chemical Identity
| Property | Value |
|---|---|
| Chemical Formula | C145H234N40O41 |
| Molecular Weight | 3195 Da |
| Peptide Class | Insect Antimicrobial Peptide (37 aa) |
| Sequence | KWKLFKKIEKVGQNIRDGIIKAGPAVAVVGQATQIAK-NH2 |
| Origin | Hyalophora cecropia (cecropia moth) |
Structure
Cecropin A is a 37-amino acid linear amphipathic alpha-helical peptide, the first antimicrobial peptide to be fully characterized (1981). It has a basic N-terminal domain and a hydrophobic C-terminal domain, forming two alpha-helices connected by a flexible hinge region. The C-terminus is amidated.
Mechanism of Action
Cecropin A disrupts bacterial membranes through its amphipathic alpha-helical structure. The N-terminal helix interacts with anionic phospholipids while the C-terminal helix inserts into the hydrophobic core of the bilayer. This forms voltage-dependent pores causing membrane depolarization and lysis, with selectivity for bacterial over eukaryotic membranes.
Clinical Applications
- Pioneer insect AMP: Founded the field of insect immunity
- Lead compound: Inspired development of synthetic AMPs
- Agricultural applications: Transgenic plant resistance
- Aquaculture: Fish and shrimp disease prevention
Pharmacology
- Spectrum: Broad (gram-positive, gram-negative)
- Hemolysis: Minimal at antimicrobial concentrations
- Salt sensitivity: Moderate
- Stability: Susceptible to proteolysis
References
- Steiner, H., et al. (1981). Sequence and specificity of two antibacterial proteins involved in insect immunity. Nature, 292, 246-248.
- Boman, H.G. (1995). Peptide antibiotics and their role in innate immunity. Annual Review of Immunology, 13, 61-92.
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