LL37 5mg*10vials Kit

Description

🧬 Protein Profile: LL-37

Systematic Name: Cathelicidin Antimicrobial Peptide (CAMP)
Synonym: hCAP-18 (human cationic antimicrobial protein 18)-derived peptide
CAS Number: 246494-35-7
Molecular Formula: C₁₇₉H₂₉₁N₅₃O₄₉
Molecular Weight: ~4,493 Da
Amino Acid Sequence: LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES
Isoelectric Point (pI): 10.9 (strongly cationic)
Structure: Amphipathic α-helix (residues 13-34) with hydrophobic N-terminus and hydrophilic C-terminus

🔍 Biological Origin & Processing

LL-37 is the only cathelicidin expressed in humans, encoded by the CAMP gene on chromosome 3p21.3. Synthesized as a 18 kDa precursor protein (hCAP-18) in neutrophils, macrophages, epithelial cells, and keratinocytes, it undergoes proteolytic cleavage by proteinase 3 to release the active 37-amino acid peptide. This processing occurs during inflammation or microbial challenge, with secretion triggered by TLR activation, vitamin D, or microbial products like LPS.

⚔️ Multifunctional Mechanisms

🦠 Antimicrobial Activity

• Broad-Spectrum Action: Effective against Gram-positive bacteria (Staphylococcus aureus, Streptococcus pneumoniae), Gram-negative bacteria (E. coli, Pseudomonas aeruginosa), fungi (Candida albicans), and enveloped viruses (HIV-1, influenza A). MIC values range from 1-10 μM for most pathogens.
• Membrane Disruption: Cationic residues (+6 net charge) interact with anionic microbial membranes, forming pores via the “carpet model” or barrel-stave mechanism. Hydrophobic N-terminal region drives insertion into lipid bilayers, causing leakage and cell lysis.
• Intracellular Targeting: Enters bacterial cytoplasm to inhibit DNA/RNA synthesis and protein folding, providing a second bactericidal mechanism.

🛡️ Immunomodulation

• Chemotaxis: Recruits neutrophils, monocytes, and T cells via formyl peptide receptor-like 1 (FPRL1) activation, with EC₅₀ of 0.1-1 μM.
• Cytokine Regulation: Induces IL-8, MCP-1, and TNF-α at low concentrations (1-5 μM) while suppressing excessive inflammation via TLR4/MD2 antagonism at higher doses (>10 μM).
• Antigen Presentation: Enhances dendritic cell maturation and MHC class II expression, bridging innate and adaptive immunity.

🔄 Tissue Repair & Regeneration

• Angiogenesis: Stimulates endothelial cell migration and tube formation via VEGFR2 activation, accelerating wound vascularization.
• Keratinocyte Proliferation: Promotes re-epithelialization by upregulating EGF receptor signaling, reducing wound closure time in murine models by 30%.
• Extracellular Matrix Remodeling: Induces MMP-2/MMP-9 expression to facilitate tissue remodeling during healing.

🩺 Clinical Significance

🧪 Research Tools & Therapeutics

• Recombinant Production: Available as synthetic peptide (≥95% purity) or E. coli-expressed protein; typically reconstituted in water or PBS with 0.1% BSA.
• Delivery Systems: Nanoparticle encapsulation enhances stability and reduces hemolytic activity (IC₅₀ >100 μM vs. 25 μM for free peptide).
• Clinical Candidates: Cationic lipopeptide derivatives (e.g., MX-226) in Phase I trials for multidrug-resistant infections; LL-37-modified hydrogels under development for chronic wound therapy.

⚠️ Biological Considerations

• Host Cell Toxicity: Hemolytic at high concentrations (>50 μM); requires careful dose optimization for therapeutic use.
• Proteolytic Degradation: Susceptible to serine proteases (e.g., elastase), necessitating protease inhibitors in formulations.
• Immunogenicity: Naturally occurring in humans, minimizing antibody formation risk compared to synthetic antimicrobials.