Frequently Asked Questions

LL-37 is the only human cathelicidin antimicrobial peptide — a 37-amino-acid peptide that serves as a key component of innate immune defense. It has direct antimicrobial, anti-biofilm, and wound healing properties.

LL-37 disrupts bacterial biofilm formation at concentrations below its bactericidal threshold. This is significant because biofilms are a major cause of antibiotic-resistant chronic infections. The mechanism involves interference with bacterial quorum sensing and surface attachment.

No. Beyond direct microbial killing, LL-37 modulates immune cell recruitment, promotes wound healing via angiogenesis and re-epithelialization, and regulates inflammatory responses through Toll-like receptor signaling modulation.

LL-37 is the only human cathelicidin antimicrobial peptide, derived from the C-terminal cleavage of the 18-kDa precursor protein hCAP18 by proteinase 3. It is a 37-amino-acid amphipathic alpha-helical peptide produced by neutrophils, macrophages, epithelial cells, and other cell types as part of the innate immune defense.

LL-37 has been investigated across 5 primary research areas: Antimicrobial Peptides, Innate Immunity, Wound Healing, Anti-Biofilm, Immunomodulation. Each area has published preclinical data supporting the peptide's activity through distinct but sometimes overlapping molecular pathways.

Hancock & Sahl (2006) reviewed antimicrobial peptides including LL-37 as key effectors of innate immunity with direct microbicidal and immunomodulatory functions. Additionally, overhage et al. (2008) demonstrated LL-37 inhibits Pseudomonas aeruginosa biofilm formation at 0.5 mcg/mL — well below its bactericidal concentration — through interference with quorum sensing.

In vitro antimicrobial studies use 1-32 mcg/mL. Anti-biofilm activity observed at 0.5-4 mcg/mL. Wound healing studies in animals use topical application of 10-100 mcg/wound.

Store lyophilized powder at -20C. LL-37 is susceptible to proteolytic degradation; reconstitute in sterile water and store at 2-8C for short-term use. Avoid repeated freeze-thaw cycles.

The CAS registry number for LL-37 is 154947-66-7. The molecular weight is 4493.33 g/mol. The amino acid sequence is: Leu-Leu-Gly-Asp-Phe-Phe-Arg-Lys-Ser-Lys-Glu-Lys-Ile-Gly-Lys-Glu-Phe-Lys-Arg-Ile-....

Key publications include: Antimicrobial and host-defense peptides as new anti-infective therapeutic strategies Among others, there are 4 peer-reviewed publications cited in our research profile, all indexed in PubMed.

Research-grade LL-37 should be at minimum 98% purity as verified by HPLC analysis. Mass spectrometry should confirm molecular identity. Always request a batch-specific Certificate of Analysis (COA) from an independent third-party laboratory before using any peptide in experiments.

Add bacteriostatic water slowly down the inside wall of the vial — never spray directly onto the lyophilized powder. Gently swirl until fully dissolved; the solution should be clear and colorless. Calculate your desired concentration based on the peptide mass and volume of solvent added. Use a sterile syringe and swab the vial stopper with alcohol before each withdrawal.

No. LL-37 is designated Research Use Only (RUO). It is not approved by the FDA for human consumption, veterinary use, or any therapeutic purpose. All references to research findings on this site describe preclinical laboratory studies, not clinical recommendations. Consult a licensed healthcare provider for any medical questions.

LL-37 and BPC-157 act through different molecular mechanisms and are studied for overlapping but distinct research applications. Researchers often use both compounds in parallel to compare pathway-specific effects. Detailed mechanism comparisons are available in our research section.

Once reconstituted, LL-37 should be stored at 2-8°C (standard refrigerator temperature) and used within 30 days. Lyophilized (unreconstituted) peptide is stable for 12-24 months at -20°C when kept sealed and protected from light. Never refreeze a reconstituted solution, and avoid repeated freeze-thaw cycles.

Research-grade LL-37 with 98%+ purity, HPLC verification, and third-party COAs is available at researchvials.com. All peptides ship from the USA with cold-chain packaging to maintain product integrity. This site is an educational resource and does not sell products directly.

Research peptides are short chains of amino acids — typically between 2 and 50 residues — synthesized for laboratory investigation. They let researchers study receptor binding kinetics, cellular signaling cascades, and enzyme interactions with high specificity. They are not intended for human use.

It means HPLC analysis confirmed that at least 98% of the lyophilized powder is your target peptide. The remaining fraction is typically truncated sequences or deletion peptides from synthesis. This matters because impurities can activate off-target pathways and wreck dose-response curves. Mass spectrometry provides the second check, confirming molecular identity.

Keep lyophilized (freeze-dried) vials at -20°C. They are remarkably stable in this form — 12 to 24 months with no significant degradation. Once you reconstitute with bacteriostatic water, move to 2-8°C and use within 30 days. The cardinal rules: no repeated freeze-thaw cycles, protect from light, sterile technique every time you draw from the vial.

It means a lab with zero financial ties to the manufacturer independently verifies identity, purity, and endotoxin levels. This eliminates the obvious conflict of interest in self-testing. The resulting Certificate of Analysis (COA) gives you hard data about what is actually in the vial — not what someone claims is in it.

Swab the vial stopper with an alcohol wipe. Draw your bacteriostatic water into a sterile syringe. Inject slowly down the inside glass wall of the vial — not directly onto the cake of powder, which can denature it. Let it sit for a minute, then gently swirl. Never shake. The solution should be perfectly clear. If it is cloudy, something went wrong.

It means the product exists solely for laboratory research — in vitro cell culture work, preclinical animal studies, and educational purposes. RUO compounds have not gone through FDA approval for human safety or efficacy. They cannot legally be sold as drugs, supplements, food additives, or for veterinary use.

Look for four things. First, HPLC purity — should be 98%+ with a clean chromatogram showing one dominant peak. Second, mass spectrometry — the observed molecular weight should match the theoretical weight within instrument precision. Third, appearance — should state white or off-white lyophilized powder. Fourth, endotoxin testing — should be below detection limits for injectable-grade material.

PubMed (pubmed.ncbi.nlm.nih.gov) is the gold standard. Search by peptide name, CAS number, or mechanism. Start with review articles — they synthesize the field so you do not have to read 50 primary papers first. Every PMID we cite on this site links directly to the PubMed entry so you can verify our claims.

This site is purely educational — we do not sell anything. All research peptides referenced here are available at researchvials.com, with 98%+ purity, third-party COAs, and USA-based cold-chain shipping.