Description
Chemical Identity
LL-37 is the only human cathelicidin antimicrobial peptide, a 37-amino acid alpha-helical peptide with the molecular formula C205H340N60O53 and a molecular weight of 4493.33 Da (CAS number 154947-66-7). The amino acid sequence is LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES, derived from the C-terminal of the precursor protein hCAP-18 (human cationic antimicrobial protein 18).
LL-37 is a cationic, amphipathic host-defense peptide that exhibits broad-spectrum antimicrobial activity against bacteria, fungi, and enveloped viruses. It plays key roles in innate immune defense, wound healing, and immunomodulation. LL-37 is also referred to as Cathelicidin, CAP-18, or hCAP-18.
| Property | Value |
|---|---|
| Molecular Formula | C205H340N60O53 |
| Molecular Weight | 4493.33 Da |
| CAS Number | 154947-66-7 |
| Sequence | LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES |
| Research Status | Phase 2 clinical trials |
Research Overview
LL-37 has been investigated in Phase 2 clinical trials and extensive preclinical research spanning antimicrobial defense, immunomodulation, wound healing, and cancer biology. The peptide acts through multiple receptors and membrane mechanisms including formyl peptide receptor 2 (FPR2/ALX), CXCR2, MRGPRX2 on mast cells, the P2X7 ion channel, and EGFR transactivation through ADAM17-mediated ectodomain shedding.
LL-37’s antimicrobial mechanism involves direct membrane disruption of microbial cells through its amphipathic alpha-helical structure, which inserts into and permeabilizes bacterial membranes. Additionally, LL-37 neutralizes lipopolysaccharide (LPS) to dampen TLR4 signaling, while forming complexes with nucleic acids to enhance TLR7/8/9 sensing of pathogens.
Key areas of published research include:
- Antimicrobial Defense: LL-37 demonstrates broad-spectrum activity against gram-positive and gram-negative bacteria, fungi, and enveloped viruses through direct membrane disruption and immunomodulatory mechanisms. Phase 2 clinical trials have evaluated LL-37 for wound infection applications.
- Wound Healing: LL-37 promotes wound repair through EGFR transactivation, stimulating epithelial proliferation and migration, as well as through angiogenic effects mediated by FPR2 and CXCR2 signaling.
- Innate Immunity: LL-37 serves as a critical effector of the innate immune system, driving chemotaxis of immune cells, NET formation in neutrophils, mast cell degranulation, and modulation of inflammatory cytokine production.
LL-37 has advanced to Phase 2 clinical trials for infectious disease applications. Research into its role in autoimmune conditions (particularly psoriasis) and cancer biology is ongoing.
Specifications
All LL-37 supplied by Prescott Bio Canada is manufactured to research-grade standards.
| Specification | Detail |
|---|---|
| Purity | >98% (HPLC) |
| Form | Lyophilized powder |
| Appearance | White to off-white powder |
| Storage (lyophilized) | -20°C, protected from light |
| Storage (reconstituted) | 2-8°C, use within 30 days |
| Solubility | Soluble in bacteriostatic water, sterile water, or normal saline |
Each vial is accompanied by a Certificate of Analysis (COA) documenting purity, identity, and endotoxin testing.
Research Applications
LL-37 is supplied exclusively for in vitro and in vivo laboratory research. Published experimental applications include:
- Antimicrobial peptide research and membrane disruption mechanism studies
- Innate immunity and host defense signaling research
- Wound healing and epithelial repair studies
- FPR2, CXCR2, and MRGPRX2 receptor pharmacology
- Biofilm disruption and infection model research
- Immunomodulation and inflammatory disease studies
Researchers should consult the primary literature and institutional review protocols before designing experiments with LL-37.
Storage and Handling
Lyophilized powder: Store at -20°C in the original sealed vial, protected from light and moisture. Under these conditions, LL-37 maintains stability for up to 24 months.
Reconstituted solution: Reconstitute with bacteriostatic water or sterile water to the desired concentration. Store reconstituted LL-37 at 2-8°C and use within 30 days. Avoid repeated freeze-thaw cycles. LL-37 may bind to plastic surfaces at low concentrations; consider using low-binding tubes.
Handling precautions: This product is intended for research use only (RUO). Not for human or veterinary diagnostic or therapeutic use. Handle using standard laboratory safety practices including appropriate PPE.