Last reviewed: October 2026 · Cleared Peptides research team
LL-37 is the 37-amino-acid active peptide released from human cathelicidin (hCAP18) and the only cathelicidin found in humans. Its name comes from its two N-terminal leucines and its length. It is a reference antimicrobial peptide in membrane biophysics and innate-immunity research.
LL-37 Structure and Identifiers
| Name | LL-37 |
|---|---|
| Synonyms | Human cathelicidin antimicrobial peptide |
| CAS number | 154947-66-7 |
| PubChem CID | 16198951 |
| Molecular formula | C205H340N60O53 |
| Molecular weight | ≈4493.3 g/mol |
| Sequence | LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES |
| Form | Lyophilized powder |
Structure and Membrane Interaction
LL-37 is cationic (net charge ≈ +6) and amphipathic, forming an α-helix in membrane-like environments. It interacts preferentially with negatively charged bacterial membranes, which is the basis of membrane-disruption and selectivity studies.
Published In-Vitro Research Areas
- Antimicrobial and anti-biofilm assays
- Lipid-membrane biophysics
- Innate-immunity signaling (TLR modulation, chemotaxis)
- Peptide aggregation and oligomerization
This summary describes laboratory research only and makes no claim about effects in humans or animals.
Purity Testing and Storage
Every lot of LL-37 supplied by Cleared Peptides is tested by an independent laboratory for identity and purity (or composition, for multi-component preparations), and the lot Certificate of Analysis is published on our COA page. Store lyophilized LL-37 at −20 °C, sealed, dry and protected from light. Allow the vial to reach room temperature before opening and minimize freeze–thaw cycles. Handle according to your institution’s chemical-hygiene procedures.
Frequently Asked Questions
What does LL-37 stand for?
It refers to the peptide’s two N-terminal leucines (LL) and its 37-residue length.
Is LL-37 for human use?
No. Cleared Peptides supplies LL-37 for laboratory research use only; it is not for human or veterinary use.
Selected References
Peer-reviewed literature on the compounds discussed in this guide, listed as scientific background for laboratory researchers. Citation does not imply endorsement by the authors or any use other than in-vitro research.
- Bucki R, et al. Cathelicidin LL-37: a multitask antimicrobial peptide. Arch Immunol Ther Exp (Warsz). 2010;58(1):15-25. PubMed 20049649 · DOI
- Verjans ET, et al. Molecular mechanisms of LL-37-induced receptor activation: An overview. Peptides. 2016;85:16-26. PubMed 27609777 · DOI
Laboratory note: solubility depends on salt form and solvent. This guide does not state a single solubility figure. Handling of lyophilized material is described in the peptide storage guide.
Research Use Only Notice
This guide is provided for educational and laboratory reference purposes. It summarizes published, primarily in-vitro and structural research literature and does not describe, recommend or imply any use in humans or animals. Products sold by Cleared Peptides are for laboratory research use only; they are not drugs, foods, cosmetics or dietary supplements, are not FDA-approved, and are not intended to diagnose, treat, cure, mitigate or prevent any disease. No dosing, administration or therapeutic information is provided.
