LL-37: Handling, Storage, and Reconstitution Guide

This guide covers lab handling, storage, and reconstitution of LL-37. LL-37 is the human cathelicidin antimicrobial peptide, supplied as a lyophilized research material. Every step below is lab best practice for in-vitro and animal-model prep. None of it is human-use instruction.

How should LL-37 be handled and stored?

Store LL-37 sealed, cool, dry, and dark. It ships as a solid, white lyophilized (freeze-dried) powder in a sealed glass vial.

• Store the powder at or below 25 degrees Celsius.
• Keep it sealed and protected from heat, light, and moisture.
• For long storage, keep it as powder and refrigerate or freeze it.

LL-37 is a large peptide. A careful cold chain helps protect its shape.

Puritide supplies LL-37 in a 5 mg vial. So the working-stock strength follows from the diluent volume chosen for that mass.

LL-37's size and sensitive shape make it harder to handle than short fragments. Gentle reconstitution and attention to buffer conditions matter more here. The peptide's behavior in later assays is tied to its shape, and the prep setting can change that shape.

Labs often choose the reconstitution solvent in advance, based on the planned assay. Water or a defined buffer can change how the peptide meets microbial or host membranes in the tests that follow.

How is LL-37 identity confirmed before use?

Check the material against its documents before any prep. The key identifiers are:

• Molecular formula: C205H340N60O53
• Molecular weight: about 4493.33 g/mol
• CAS number: 154947-66-7
• Synonyms: cathelicidin LL-37 and hCAP18 (134-170)

Matching these to the certificate of analysis is the first tracing checkpoint. It anchors the membrane and immune assays described in the LL-37 mechanism of action.

How is LL-37 reconstituted for in-vitro work?

Reconstitute LL-37 with a solvent that suits the assay. Bacteriostatic water or a suitable buffer is common for in-vitro prep. Add the diluent slowly down the inner wall of the vial, not onto the powder. Let the peptide dissolve gently. Swirl the vial. Do not vortex hard or shake it, since this can shear the peptide.

• Add diluent down the vial wall, not onto the pellet.
• Allow gentle, full dissolving of this larger peptide.
• Note that buffer and ionic conditions can affect activity.
• Work out concentration from the labeled mass and the diluent volume.

Why do buffer and ionic conditions matter for LL-37?

LL-37 is cationic, meaning it carries a positive charge. Its shape is also sensitive to its setting. So its membrane behavior can depend on buffer makeup and ionic strength.

Choose and record assay conditions with care, so results can be repeated. This handling detail directly supports the antimicrobial designs in the LL-37 research applications.

How should LL-37 be aliquoted and kept in the cold chain?

Split reconstituted LL-37 into single-use aliquots to limit freeze-thaw cycles. Label each one with:

• Compound name
• Concentration
• Date
• Lot number

Store aliquots frozen for longer holds. Keep working solutions cold and shielded from light. Hold conditions steady through the study and check storage records. The same practice appears in the KPV handling guide and the ARA-290 handling guide.

How is the LL-37 COA and lot verified?

Each LL-37 batch ships with a certificate of analysis (COA) checked by a third party. It documents:

• Purity by HPLC or reverse-phase chromatography
• Identity confirmed by mass spectrometry
• Lot, testing date, and method details

Check the COA against the vial label. Keep it with the batch records. Sample COAs can be requested before purchase.

What PPE and institutional rules apply to LL-37?

Handle LL-37 as an investigational material. Follow the lab's SOPs, chemical hygiene plan, and approved protocols.

• Wear a lab coat, gloves, and eye protection.
• Use engineering controls where required.
• Have trained staff do all handling in controlled spaces.

Specs are on the LL-37 product page.

At intake, match the vial to its recorded synonyms, such as cathelicidin LL-37 and hCAP18 (134-170). Confirm that it looks like the expected white lyophilized powder. LL-37's activity depends on its setting. So pair intake checks with careful records of buffer conditions. That gives later teams the full context they need to repeat a result.

Why record buffer and assay conditions for LL-37?

For LL-37, prep records should go beyond the vial to the assay setting. Buffer makeup and ionic strength shape the peptide's behavior. Record these items together:

• The reconstitution solvent
• Any assay buffer
• The ionic conditions
• The lot number and certificate of analysis

Together, they give a full account of the factors that shape an LL-37 result.

This matters most for antimicrobial designs, where salt concentration can weaken activity. Logging these conditions lets a later team repeat both the material and the setting where it was tested. For a context-dependent peptide like LL-37, that is essential to repeatable work.

Steady handling is, in the end, a way to make results repeatable. Picture an LL-37 batch that is checked against its COA, mixed gently, aliquoted to limit freeze-thaw, stored in a stable cold chain, and fully recorded. It gives every later experiment the same reliable starting material. That consistency lets separate labs compare results and build on each other's work with confidence.

Sometimes a study later proves hard to repeat. A full handling record often lets labs tell a real biological difference from a prep artifact. That is why careful LL-37 handling pays off across a whole project.

For research use only. These handling notes describe laboratory practice for LL-37 as a research material supplied by Puritide Research. LL-37 is not approved for human or veterinary use, and nothing here constitutes medical or administration guidance.