We report net peptide content, not just purity — so the milligrams you dose aren't padded with water and counter-ion. RP-HPLC purity and ESI-MS identity, on a lot-numbered COA.
Net peptide content, not just purity — RP-HPLC + ESI-MS, lot-numbered COA.
Net peptide content on every lot's COA.
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Cathelicidin antimicrobial peptide
Lyochem primary owner
This Lyochem page is the primary SEO owner for research labs, CROs, and method-development teams qualifying LL-37 as a documented research-standard lot. The page should answer whether the buyer can review HPLC purity, identity confirmation, lot continuity, stability handling, and assay-fit documentation before ordering.
Overview
LL-37 is a 37-residue cationic antimicrobial peptide (sequence LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES) and the sole human cathelicidin, liberated by proteolytic cleavage of the hCAP-18 precursor. In membrane-mimetic environments it folds into an amphipathic α-helix whose high positive charge drives direct membrane disruption; targets span Gram-positive and Gram-negative bacteria, fungi, and enveloped viruses. It also signals through formyl-peptide receptor 2 (FPR2) to modulate innate immunity beyond that lytic action, and is studied in wound-healing chemotaxis, autoimmunity, and inflammatory-disease research. Lyochem supplies LL-37 as a lyophilized reference standard at ≥99.0% HPLC purity, with RP-HPLC and ESI-MS confirming purity and the intact 37-residue mass. Two practical cautions accompany this peptide. First, its dense cationic charge makes it adsorb strongly to ordinary polypropylene and glass at low working concentrations, and 30-70% of the weighed-out material can be lost before it reaches the assay unless low-bind labware is used. Prepare working dilutions in low-bind tubes, adding a carrier — either 0.1% acid-free BSA or 0.01% Tween-20 — to suppress that adsorption. Second, because LL-37's innate-immune signaling shares pathways with bacterial endotoxin, LAL endotoxin testing and microbial limits are essential add-ons for any cell-based or in vivo work.
Applications & buyer fit
Buyers in this category are research labs studying immune-modulation, cytokine signalling, and antimicrobial activity. The defining QC requirement is bacterial-endotoxin control: many downstream assays (NF-κB reporters, macrophage-activation panels, neutrophil-priming readouts) are themselves activated by endotoxin contamination, so a clean LAL on the specific lot is a precondition rather than a nice-to-have. LL-37 and related cationic antimicrobial peptides additionally benefit from low-bind plasticware during dilution.
Academic Laboratories
Universities, medical schools, and government research institutes qualifying a reference standard for a method-development or in vivo workflow.
Every release ships with its own batch-specific CoA — identity, purity, and the analytical scope agreed at quote stage, tied to the exact lot you receive.
Review a representative batch CoA before you order, so you can confirm the packet matches what your method or sponsor audit needs.
Supplied strictly as a research reagent to research institutions — not a finished dosage form and not for human administration. Buyer qualification runs at the inquiry stage.
Specifications
Documentation available on request
Regulatory note
Sold for Research Use Only under the receiving laboratory's institutional and jurisdictional regulations. Not a finished dosage form, not labelled for human administration, not for in-vitro diagnostic use. For NF-κB reporter, macrophage, neutrophil, and any other endotoxin-sensitive assay, request LAL testing on the specific lot as a precondition.
Selected literature
Frequently asked questions
At 37 residues LL-37 sits near the upper end of routine solid-phase synthesis, so identity rests on ESI-MS or LC-MS confirming the intact mass across the expected multiply-charged envelope, paired with RP-HPLC for chromatographic purity. Its high net positive charge and amphipathic helix influence column retention and can cause peak tailing, so gradient conditions and a reference-standard retention comparison are worth reviewing on the COA. Because the same cationic character promotes surface adsorption, analysts should also confirm the reported purity reflects recovered material rather than a value distorted by binding losses during sample handling.
A peptide this cationic pairs with a large number of counter-ions, and trifluoroacetate in particular can persist from purification. The salt contributes meaningfully to the weighed powder mass, so knowing whether the material is a TFA or acetate salt is necessary to convert powder mass into net peptide. This is compounded by lyophilization water. For quantitative work at sub-microgram-per-milliliter concentrations, where adsorption already erodes the effective dose, an unaccounted salt fraction is a second systematic error, so the batch record should state both the salt form and the assay-determined net content.
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