LL-37
Only human cathelicidin antimicrobial peptide, providing broad-spectrum defense and immunomodulatory functions at mucosal surfaces.
Chemical Identity
| Property | Value |
|---|---|
| Gene | CAMP (hCAP18) |
| Molecular Weight | 4493 Da |
| Amino Acids | 37 (LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES) |
| Peptide Class | Cathelicidin (Alpha-helical AMP) |
| Source | Neutrophils, epithelial cells |
Structure
LL-37 is the only cathelicidin family antimicrobial peptide in humans, derived from the C-terminal end of the hCAP18 precursor protein. It is a 37-amino acid amphipathic alpha-helical peptide starting with two leucine residues (hence the name). It adopts an alpha-helical conformation in membrane-mimetic environments.
Mechanism of Action
LL-37 disrupts bacterial membranes through its amphipathic helical structure, with cationic residues binding anionic phospholipids and hydrophobic residues inserting into the lipid bilayer. Beyond direct killing, it has potent immunomodulatory effects: chemotaxis of neutrophils, monocytes, and T cells; promotion of wound healing; and modulation of inflammatory cytokine expression.
Clinical Applications
- Innate immune defense: Broad-spectrum antimicrobial (gram-positive, gram-negative, fungi)
- Wound healing: Promotes re-epithelialization and angiogenesis
- Cystic fibrosis: Deficient in CF airways, therapeutic potential
- Psoriasis: Overexpressed in psoriatic lesions
- Cancer: Anti-tumor activity under investigation
Pharmacology
- Spectrum: Broad (bacteria, fungi, enveloped viruses)
- Salt sensitivity: Partially sensitive to NaCl
- Biofilm disruption: Active against bacterial biofilms
- Anti-endotoxin: Neutralizes LPS
References
- Gudmundsson, G.H., et al. (1996). The human gene FALL39 and processing of the cathelin precursor. Journal of Biological Chemistry, 271, 2447-2454.
- Zanetti, M. (2004). Cathelicidins, multifunctional peptides of the innate immunity. Journal of Leukocyte Biology, 75, 39-48.
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