LL-37 (5mg)

Human Cathelicidin Antimicrobial Peptide | hCAP18 Derivative

The 4Balance Codex: The Innate Immune Sentinel and Biofilm Disruptor.

Product Overview

LL-37 is a 37-amino acid, cationic (positively charged) peptide and the sole human member of the cathelicidin family of antimicrobial peptides (AMPs). It is proteolytically cleaved from its inactive precursor protein, hCAP18, primarily by proteinase 3 in neutrophils. LL-37 is a critical multifunctional component of the innate immune system. In the research setting, it is the definitive agent for studying immediate host defense mechanisms, the disruption of bacterial biofilms, and the complex modulation of inflammatory signaling pathways.

Format: 5mg Lyophilized Powder Sequence Length: 37 Amino Acids Classification: Amphipathic Cationic Peptide / Alarmin

Mechanism of Action: Membrane Lysis & Immune Signaling

LL-37’s efficacy in research models stems from its two distinct modes of action: direct bacterial killing and host immune modulation.

1. Rapid Membrane Disruption: The peptide displays potent bactericidal activity through electrostatic attraction. Its positive charge binds avidly to the negatively charged lipopolysaccharides (LPS) of Gram-negative bacteria or lipoteichoic acids (LTA) of Gram-positive bacteria. Once attached, its amphipathic alpha-helical structure inserts into the bacterial lipid bilayer, creating transmembrane pores (the toroidal pore model) that lead to immediate osmotic instability and cell lysis.

2. Immunomodulation as an "Alarmin": Beyond killing bacteria, LL-37 acts as a powerful chemotactic signal. By binding to Formyl Peptide Receptor 2 (FPR2) and the P2X7 receptor on host immune cells, it recruits neutrophils, monocytes, and T-cells to sites of infection or injury.

3. Biofilm Interference: Research indicates LL-37 is highly effective at inhibiting the formation of bacterial biofilms and degrading existing ones (notably in Pseudomonas aeruginosa) at concentrations below those required for direct killing, likely by interfering with bacterial quorum sensing systems.

Research Applications

In the 4Balance Research Array, LL-37 is utilized to investigate host defense in conditions where traditional antibiotics fail.

• Chronic Wound Healing: Studies suggest LL-37 is essential for normal cutaneous wound repair. It is researched for its ability to stimulate angiogenesis (new blood vessel formation) and promote keratinocyte migration (re-epithelialization) to close wounds.

• Sepsis & Endotoxin Neutralization: LL-37 has been shown to bind directly to circulating LPS (endotoxin), potentially dampening the runaway inflammatory response seen in septic shock models.

• The Autoimmunity Paradox: Conversely, it is used to study the pathophysiology of conditions like psoriasis and rosacea, where the overexpression of LL-37 drives chronic inflammation and "self-DNA" recognition, highlighting its complex role as a double-edged sword in immunity.

Technical Specifications

• Mass: 5mg (Lyophilized Peptide)

• Molecular Formula: C₂₀₅H₃₄₀N₆₀O₅₃

• Molecular Weight: 4493.3 g/mol

• Solubility: Water Soluble (Requires Bacteriostatic Water or Sterile Saline)

• Storage: Store lyophilized at -20°C. Due to its potential to aggregate and adsorb to surfaces, reconstituted LL-37 should be handled carefully and used promptly for best experimental results.

References

1. Vandamme, D., et al. (2012). Cathelicidins: warrior peptides of the innate immunity. Immunology and Cell Biology.

2. Overhage, J., et al. (2008). Human host defense peptide LL-37 prevents bacterial biofilm formation. Infection and Immunity.

3. De, Y., et al. (2000). LL-37, the neutrophil granule–and epithelial cell–derived cathelicidin, utilizes formyl peptide receptor-like 1 (FPRL1) as a receptor to chemoattract human peripheral blood neutrophils, monocytes, and T cells. The Journal of Experimental Medicine.

4. Carretero, M., et al. (2008). In vitro and in vivo wound healing-promoting activities of human cathelicidin LL-37. Journal of Investigative Dermatology.

5. Lande, R., et al. (2007). Plasmacytoid dendritic cells sense self-DNA coupled with antimicrobial peptide. Nature.

DISCLAIMER: FOR RESEARCH USE ONLY. This product is a laboratory reagent intended strictly for in-vitro research and development. It is not for human consumption, veterinary use, or therapeutic application. Bodily introduction of any kind is strictly prohibited by law.