Human Cathelicidin / Host Defense Peptide
LL-37 (Human Cathelicidin) Research Peptide
LL-37 is the C-terminal 37-amino acid antimicrobial peptide derived from the human cathelicidin precursor protein hCAP-18, encoded by the CAMP gene. It is the only known human cathelicidin and functions as a broad-spectrum host defense peptide with antimicrobial, immunomodulatory, and wound-healing properties studied across a wide range of preclinical models.
Compound identity
- Name
- LL-37
- Class
- Human Cathelicidin / Host Defense Peptide
- CAS number
- 154947-66-7
- Molecular formula
- C₂₀₅H₃₄₀N₆₀O₅₃S
- Also known as
- Human Cathelicidin LL-37, hCAP18 C-terminal peptide, CAMP peptide
- Sequence
- Leu-Leu-Gly-Asp-Phe-Phe-Arg-Lys-Ser-Lys-Glu-Lys-Ile-Gly-Lys-Glu-Phe-Lys-Arg-Ile-Val-Gln-Arg-Ile-Lys-Asp-Phe-Leu-Arg-Asn-Leu-Val-Pro-Arg-Thr-Glu-Ser (37 aa; MW ~4493 Da)
Research context
Human cathelicidin hCAP-18 is a 18-kDa precursor protein expressed primarily in neutrophil granules, mast cells, and epithelial cells of the skin, lung, and gut. Processing by serine proteases (elastase in neutrophils, kallikrein in skin) releases the 37-amino acid C-terminal mature peptide LL-37 (CAS 154947-66-7, MW ~4493 Da, C₂₀₅H₃₄₀N₆₀O₅₃S). The name LL-37 derives from the two N-terminal leucine residues and the 37-residue length. The peptide adopts an amphipathic α-helical structure in membrane-mimetic environments, which underlies its membrane-disrupting antimicrobial activity. LL-37 is expressed constitutively at low levels and is upregulated by innate immune stimuli including microbial products, 1,25-dihydroxyvitamin D₃, and proinflammatory cytokines.
Research on LL-37 spans multiple biological domains. In antimicrobial research, LL-37 has been studied against a broad panel of bacteria (including MRSA, Pseudomonas aeruginosa, E. coli), fungi, viruses, and protozoa — its amphipathic helix disrupts pathogen membranes. Immunomodulatory research (work by Bowdish, Bhattacharyya, Hancock, and others) has characterized LL-37's interactions with Toll-like receptors, its ability to neutralize bacterial lipopolysaccharide (LPS), and its effects on macrophage, dendritic cell, and neutrophil function. Wound-healing research has examined LL-37's chemoattractant effects on epithelial cells, keratinocytes, and endothelial cells, and its role in re-epithelialization. LL-37 has also been studied in the contexts of cancer biology (receptor-mediated effects on tumor cells and angiogenesis) and dermatology (altered expression in atopic dermatitis, psoriasis, and rosacea).
As a research reagent, LL-37 is used in antimicrobial peptide biology, innate immunity research, wound-healing assays, and studies of cathelicidin-mediated immunomodulation. DMV Research supplies LL-37 as a lyophilized peptide with per-batch Certificate of Analysis confirming identity by mass spectrometry and purity ≥99% by HPLC.
Frequently asked questions
What is LL-37?+
LL-37 (CAS 154947-66-7) is the sole human cathelicidin — a 37-amino acid host defense peptide derived from the C-terminal region of the hCAP-18 precursor protein (encoded by the CAMP gene). It is produced by neutrophils, mast cells, and epithelial cells and functions as a broad-spectrum antimicrobial peptide with additional immunomodulatory and wound-healing properties characterized in preclinical research.
What is the mechanism of LL-37 antimicrobial activity?+
LL-37 adopts an amphipathic α-helical secondary structure in membrane-mimetic environments. This helical conformation concentrates cationic and hydrophobic residues on opposing faces of the helix, enabling membrane insertion and disruption of bacterial, fungal, and viral membranes. The mechanism is broadly effective against both gram-positive and gram-negative bacteria. LL-37 also neutralizes bacterial lipopolysaccharide (LPS), preventing TLR4 activation and downstream inflammatory signaling.
Is LL-37 only an antimicrobial peptide?+
No. LL-37 has multiple characterized activities beyond direct antimicrobial membrane disruption. Immunomodulatory research has documented LL-37's ability to modulate Toll-like receptor signaling, activate chemokine receptors (FPRL-1/FPR2), recruit immune cells (neutrophils, monocytes, mast cells), and influence dendritic cell maturation. Wound-healing research has characterized chemoattractant effects on keratinocytes and endothelial cells. Cancer biology studies have identified LL-37 receptor interactions (ErbB2, EGFR). LL-37 is thus studied as a pleiotropic host defense molecule rather than a simple antimicrobial agent.
Is LL-37 approved for human use?+
No. LL-37 is not FDA-approved for any indication. It is an endogenous peptide and research reagent. As supplied by DMV Research, it is for in-vitro and pre-clinical laboratory research purposes only. Not for human consumption.
Research use only
All products are intended for laboratory and research use only (RUO) and are not for human consumption, ingestion, or any in-vivo use.
The statements on this page have not been evaluated by the FDA. LL-37 is not intended to diagnose, treat, cure, or prevent any disease. Content is provided for laboratory research reference only.