LL-37 (CAS 154947-66-7) is a synthetic 37-residue human cathelicidin research peptide. It is supplied for laboratories, biotechnology companies, contract research organizations, assay developers, and other professional research teams that need a clearly identified material. The main purchasing value is straightforward: receives a defined product name, molecular identity, agreed quality target, lot-specific documents, and packaging selected for the project.

For routine research, a commonly requested purity target is at least 98% by chromatographic analysis, but the final agreed specification and actual result must appear on the certificate for the delivered lot. Customers  with concentration-sensitive work may also request information on content or assay basis, water, salt or counter-ion form, and other attributes relevant to their method.

LL-37 is sensitive to experimental conditions and may adsorb to some plastics or form concentration-dependent assemblies. A customer comparing quotations should therefore look beyond headline purity and ask about peptide content, salt form, container choice, analytical method, and handling guidance.

How It Works

LL-37 carries many positively charged residues. This allows it to interact with negatively charged membrane surfaces and with biological molecules in the surrounding medium. Researchers use it to observe membrane effects, immune-signaling changes, cell migration, and communication between epithelial and immune cells. The result can change greatly with salt level, serum, medium composition, concentration, and contact time.

The material does not create one automatic or universal result. The observed response depends on the model, concentration, exposure time, controls, sample preparation, and measurement method. For that reason, it is best treated as a defined research input that helps a team test a question under controlled conditions.

Common Research Applications

Innate-immunity models. Used to study signaling linked to the body's first-line defense system, including cytokine communication and immune-cell recruitment in controlled models.

Membrane-interaction assays. Supports studies of peptide binding to model membranes, membrane integrity, lipid composition, and concentration-dependent selectivity.

Microbial research. Can be evaluated in standardized growth, membrane, and viability assays. Buyers should compare methods carefully because media and endpoint choices strongly affect apparent activity.

Biofilm models. Used to study surface attachment, biofilm formation, mature biofilm response, and combination effects with suitable controls.

Epithelial and skin-biology models. Supports research on barrier signaling, keratinocyte or fibroblast migration, extracellular-matrix responses, and tissue-stress communication.

Structure-activity screening. Useful for comparing full-length LL-37 with fragments, modified sequences, or related host-defense peptides.

Quality and Batch Documentation

Quality should be judged from more than one number. Chromatographic analysis is used to estimate relative purity under a defined method. Mass analysis supports confirmation that the principal component has the expected molecular mass. Depending on the product and project, additional information may include appearance, content or assay basis, water, residual processing components, salt form, solution behavior, or other agreed tests.
A useful lot package can include a Certificate of Analysis, chromatogram, mass spectrum, product name, CAS number, batch number, test date, storage statement, quantity basis, and release result. Buyers should request any special document or test before production or release, because not every optional test can be added after the material has shipped.
HPLC and MS answer different questions. HPLC helps show how clean the sample appears in that test. MS helps show whether the main material has the expected mass. A high HPLC purity result does not replace identity confirmation, and an expected mass does not by itself describe the full purity profile.

Handling and Storage

Store tightly closed under the condition stated for the delivered lot. During solution preparation, keep solvent, salt level, container type, mixing method, and standing time consistent. Low-binding tubes may improve recovery at low concentration. Prepare aliquots for repeated work and avoid uncontrolled freeze-thaw history.

The label and lot certificate take priority over general website text. If the planned method is sensitive to moisture, adsorption, light, temperature, or solution age, these conditions should be written into the laboratory procedure and kept consistent from one run to the next.

Packaging, Supply, and Custom Options

Packaging can be discussed according to project stage. Small packs are practical for feasibility work, while repeated studies may benefit from several matched units or material reserved from one lot. Larger research quantities, split filling, custom labeling, additional testing, or related sequence work can be reviewed before quotation. Feasibility, lead time, and price depend on the exact specification.
A clear inquiry should include the product name, CAS number, required quantity, desired purity, preferred packaging, destination, document needs, and any special test. This reduces back-and-forth and helps the supplier quote the correct material rather than a similarly named product. If lot continuity is important, the expected total project demand should be discussed early.

Why Choose This Product

Clear identity. The product is described by its accepted name, CAS number, and relevant molecular information, reducing the risk of ordering a similarly named material.
Practical quality evidence. A defined purity target can be combined with identity data and lot-specific documentation, giving the buyer more useful evidence than a purity claim alone.
Flexible project support. Packaging, quantity, additional analysis, and related custom work can be discussed according to the research plan.
Consistent communication. Product form, calculation basis, storage, documents, and special requirements can be confirmed before shipment so purchasing, quality, and research teams work from the same information.

Frequently Asked Questions

What should be confirmed before ordering? Confirm the exact product name, CAS number, molecular form, required quantity, purity target, packaging, destination, and document list. For modified or species-specific materials, also confirm the complete sequence and modification pattern.

Does 98% purity mean 98% active content? Not necessarily. Chromatographic purity is usually a relative peak-area result. Water, counter-ions, salts, and other non-volatile components may affect the weighed amount. Ask for the content basis when exact molar preparation is important.

Which documents are commonly available? A lot-specific Certificate of Analysis is the main document. Supporting chromatographic and mass data can be discussed, together with any additional test agreed before release.

Can the package size be customized? Yes, subject to material compatibility and production feasibility. Small research packs, multiple matched units, or larger research quantities can be reviewed during quotation.

How should a working concentration be selected? There is no single concentration suitable for every model. Researchers should begin with relevant published methods or prior internal data, then perform a range study with suitable controls.

How long can a prepared solution be kept? The answer depends on solvent, concentration, pH, temperature, light, container, and assay requirements. Use freshly prepared solution when possible or establish a validated holding period for the specific method.

Why is the lot certificate important? The certificate connects the physical material to its batch number, test results, product form, and storage statement. General website information cannot replace the delivered lot record.

Who is the intended customer? The material is intended for trained professionals in qualified laboratory, biotechnology, industrial research, academic, or contract research settings.

Research-Use Statement

This material is supplied solely for laboratory research and analytical work by trained professionals. It is not supplied for human or veterinary use, food use, household use, or diagnostic procedures. The purchaser is responsible for assessing suitability, reviewing the lot documents, establishing safe laboratory procedures, and following applicable institutional and local requirements.