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LL-37

Price range: $69.00 through $129.00

  • Contents: LL-37 (Human cathelicidin antimicrobial peptide; 37-amino acid)
  • Form: Lyophilized powder
  • Purity: >99%
Quantity Discount Price
1 - 3 - -
4 - 7 10% -
8 + 18% -
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Description

LL-37 is the only human cathelicidin, a 37-amino acid amphipathic alpha-helical peptide cleaved from its 18-kDa precursor protein hCAP18 by proteinase 3. Its name reflects both its length and the two leucine residues at its N-terminus. Produced by neutrophils, macrophages, mast cells, and epithelial cells as part of the first-line innate immune response, LL-37 operates through direct membrane disruption of microbial lipid bilayers via electrostatic interaction with negatively charged phospholipid head groups. Beyond direct antimicrobial activity, it modulates innate immune signaling through LPS endotoxin neutralization, immune cell chemotaxis, and biofilm disruption. This multi-functional profile makes it a central research tool in specialty research peptide innate immunity models.

Chemical Information

  • Chemical Name: LL-37 (LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES)
  • Also Known As: CAP-18 (37-residue active fragment); cathelicidin antimicrobial peptide
  • Compound Class: Human host-defense peptide; cathelicidin family antimicrobial and immunomodulatory 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
  • Molecular Formula: C205H340N60O59
  • Molecular Weight: 4493.3 g/mol
  • CAS Number: 197961-49-4

Applications

  • Antimicrobial mechanism and membrane-disruption research. LL-37 is the only cathelicidin-family antimicrobial peptide expressed in humans, proteolytically cleaved from the precursor protein hCAP-18. Its amphipathic alpha-helical structure disrupts negatively charged bacterial membranes, making it a reference compound for studying cationic host-defense peptide activity against Gram-positive and Gram-negative bacteria
  • Innate immune signaling and chemotaxis research. Beyond direct membrane disruption, LL-37 engages host cell receptors including formyl peptide receptor 2 (FPR2) and P2X7, driving immune cell chemotaxis and cytokine release modulation, supporting its use in innate immunity and inflammatory signaling research
  • Wound healing and angiogenesis research. LL-37 has documented pro-angiogenic and keratinocyte-migration-promoting effects, making it a tool for studying peptide-mediated wound repair alongside other regenerative research peptides such as GHK-Cu and BPC-157
  • Antimicrobial resistance and peptide antibiotic research. As a naturally occurring antimicrobial peptide with a membrane-targeting mechanism, LL-37 is used in comparative research on peptide-based antimicrobial strategies as an alternative to conventional small-molecule antibiotics, particularly in resistance-related study designs

Storage and Handling

Store lyophilized powder at -20C for long-term stability, or at 2-8C for short-term use. Protect from heat, moisture, and direct light. Reconstitute with sterile water or an appropriate aqueous buffer immediately before use; store reconstituted solution at 2-8C and avoid repeated freeze-thaw cycles.

Compliance Notice

LL-37 is for laboratory research use only. It is not for human or veterinary use and carries no therapeutic, diagnostic, or clinical indication. This product has not been evaluated by the FDA. By purchasing this product, the buyer confirms that they will follow appropriate institutional safety procedures and use it exclusively for controlled research.

Frequently Asked Questions

What is LL-37?

LL-37 is the only human cathelicidin antimicrobial peptide — a 37-amino acid amphipathic alpha-helix cleaved from the hCAP18 precursor by proteinase 3. It is produced by multiple innate immune cell types and acts through direct disruption of microbial lipid bilayers, LPS endotoxin neutralization, biofilm dissolution, and immune cell chemotaxis recruitment. Its dual role as a direct antimicrobial agent and an immunomodulator makes it a central research tool in innate immunity studies.

How does LL-37's membrane disruption mechanism work?

LL-37 carries a net positive charge that enables electrostatic attraction to negatively charged bacterial membrane phospholipids. Upon contact, it adopts an amphipathic alpha-helical structure that embeds into the lipid bilayer. The mode of disruption depends on membrane lipid composition — unsaturated phospholipid bilayers trigger pore formation, while saturated phospholipid membranes produce nanofibre-mediated lipid extraction. This mechanistic duality reflects LL-37's capacity to disrupt structurally diverse bacterial membranes through different physical interaction pathways.

Why does LL-37's dual pro- and anti-inflammatory activity matter for research design?

LL-37 does not have a fixed inflammatory signaling direction — it can amplify or suppress inflammatory responses depending on concentration, cell type, and the specific signaling context. At the sites of infection, high local concentrations produce a strong pro-inflammatory response that recruits immune cells. At lower concentrations, anti-inflammatory effects predominate. Researchers designing LL-37 experiments must account for this concentration-dependent duality when interpreting cytokine output data, as the same compound can produce opposing downstream effects under different experimental conditions.

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