LL-37 is a well-characterised antimicrobial peptide derived from the C-terminal end of human cathelicidin antimicrobial protein (hCAP18). In laboratory settings, it is extensively studied for its ability to disrupt bacterial membranes and modulate cellular signalling pathways. As a prominent research chemical UK laboratories utilise, this peptide is essential for investigating chemotaxis, angiogenesis, and immune cell recruitment in vitro. The complex amphipathic structure of LL-37 requires precise peptide synthesis to ensure the correct alpha-helical conformation is maintained in aqueous environments. When preparing laboratory stock solutions, researchers must follow strict reconstitution protocols to prevent aggregation and preserve molecular stability over time. Studies show that LL-37 interacts with various cell surface receptors, such as FPR2, initiating intracellular cascades that promote cellular migration and proliferation. Similar to the cellular mechanisms discussed in Bpc 157 Nitric Oxide Synthase Endothelial Cells Survival, LL-37 can significantly influence endothelial cell behaviour during controlled in vitro assays. Further structural and chemical data regarding this peptide can be found on PubChem.
Public search data clusters around the phrase "immune defence" when indexing LL-37 laboratory models. Research trends summarise those papers as observations in isolated cell cultures and synthetic membranes, not as a consumer protocol. Amino Peptides supplies this compound only as a lyophilised laboratory reagent. Strictly for laboratory research.
- Binds directly to formyl peptide receptor-like 1 (FPRL1), facilitating intracellular signalling cascades in isolated mononuclear cell models.
- Interacts with the purinergic receptor P2X7, mediating membrane depolarisation and subsequent efflux of intracellular ATP in cell-free systems.
- Demonstrates high-affinity electrostatic interactions with anionic phospholipid bilayers, initiating membrane permeabilisation in synthetic liposome models.
- Engages with epidermal growth factor receptor (EGFR) pathways via metalloproteinase-dependent transactivation in cultured epithelial cells.
- Induces the formation of transmembrane pores via a carpet-like mechanism, disrupting the structural integrity of synthetic bacterial membranes.
- Modulates intracellular calcium mobilisation and mitogen-activated protein kinase (MAPK) phosphorylation in isolated cellular experiments.
- Neutralises lipopolysaccharide (LPS) toxicity by binding directly to the lipid A moiety, preventing subsequent toll-like receptor 4 (TLR4) activation in molecular models.
- Promotes the transcription of chemokine genes through the activation of NF-κB and AP-1 transcription factors in controlled laboratory cell cultures.
Technical Specifications
Variant Breakdown
- 5mg Vial: Provided as a lyophilised solid, this 5mg quantity is ideal for establishing standard laboratory stock solutions. It allows researchers to perform multiple high-throughput screening assays while ensuring precise concentration control during serial dilutions.
Quality Assurance
- HPLC Verification: High-performance liquid chromatography is utilised to confirm a purity level exceeding 99%, ensuring the absence of truncated peptide impurities.
- Mass Spectrometry: The exact molecular weight is verified using advanced mass spectrometry, confirming the structural integrity of the synthesised sequence.
- Lyophilised Form: The peptide is supplied as a stable lyophilised powder, optimised to prevent degradation during transport and long-term laboratory storage.
- Laboratory Characterisation: Each batch undergoes rigorous endotoxin testing to guarantee levels remain below 0.5 EU/mg, preventing unwanted immune activation in sensitive cell cultures.
Research Mechanism
- Membrane Disruption: LL-37 adopts an amphipathic alpha-helical structure that allows it to insert into and disrupt negatively charged bacterial cell membranes, leading to cellular lysis in vitro.
- Receptor Binding: The peptide binds to specific G-protein coupled receptors, primarily FPR2 (formyl peptide receptor 2), triggering intracellular calcium mobilisation and downstream signalling cascades.
- Chemotaxis and Migration: Activation of these signalling pathways induces the directed migration of various cell types, including macrophages and endothelial cells, across laboratory assay gradients.
- Angiogenic Signalling: LL-37 stimulates the formation of new blood vessel-like structures in endothelial cell cultures by upregulating the expression of vascular endothelial growth factor (VEGF).
- Immune Modulation: In cellular models, the peptide modulates the release of pro-inflammatory and anti-inflammatory cytokines, providing a mechanism to study cellular immune responses without human application.
Reconstitution & Storage Data
| Vial Strength | Solvent Added | Resulting Concentration |
| 5mg | 1 mL Bacteriostatic Reconstitution Solution | 5.00 mg/mL |
| 5mg | 2 mL Bacteriostatic Reconstitution Solution | 2.50 mg/mL |
- Lyophilised (Powder): Store in a standard refrigerator (2-8°C) for up to 3 months. For long-term preservation, freeze at -20°C.
- Reconstituted (Liquid): Store at 2-8°C (Refrigerated).
Scientific References
Journal of Leukocyte Biology: "The human antimicrobial peptide LL-37 is a multifunctional modulator of innate immune responses" View Study
Biochimica et Biophysica Acta: "LL-37, the only human member of the cathelicidin family of antimicrobial peptides" View Study
Journal of Biological Chemistry: "Cathelicidin LL-37 induces angiogenesis via PGE2-EP3 signaling in endothelial cells" View Study
Journal of Innate Immunity: "LL-37 triggers formation of Streptococcus pyogenes extracellular vesicle-like structures with immune stimulatory properties" View Study
Bone: "The antimicrobial peptide LL-37 alters human osteoblast proliferation and differentiation" View Study
