Research compound reference
LL-37
LL-37 is a synthetic linear peptide of 37 amino acids. The material is a white to off-white lyophilized powder of 99% or greater purity by HPLC, with a lot-specific Certificate of Analysis, for in vitro laboratory research. This page is a technical reference to the material's identity, chemistry, analytical testing and laboratory handling.
For research use only. Not for human or veterinary, diagnostic or therapeutic use.
The sequence, residue by residue
A single unbranched chain of 37 amino acids, read from the free amino end (N-terminus) to the free carboxylic acid end (C-terminus).1
H-LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES-OH
What is LL-37?
LL-37 is a synthetic linear peptide of 37 amino acids. It is catalogued under CAS 154947-66-7 and PubChem CID 16198951, with the molecular formula C205H340N60O53 and a molecular weight of 4493 g/mol.1
The material described on this page is a synthetic peptide intended as a laboratory reagent.
Composition
The 37 residues are lysine (×6), arginine (×5), leucine (×4), phenylalanine (×4), glutamic acid (×3), isoleucine (×3), aspartic acid (×2), glycine (×2), serine (×2), valine (×2), asparagine, glutamine, proline and threonine. Counting a free amino end and a free carboxylic acid end, the peptide carries a calculated net charge of about plus six at pH 7.
The sequence contains no cysteine, methionine or tryptophan, the residues most prone to air oxidation in peptides.2
The name
The name LL-37 reflects the two leucine residues at the N-terminus and the 37-residue length.1
Handling
LL-37 is a dry solid as received in the laboratory. General handling guidance for lyophilized peptides applies.2
How each lot is tested
Each lot is tested by an independent third-party laboratory.3 The LL-37 certificate page names the testing laboratories and lists each lot's purity, net content and test date. Three measurements are reported.
Identity
Mass spectrometry
Checks that the measured molecular mass matches LL-37. The calculated monoisotopic mass is 4490.58 Da.1
A matching mass is consistent with the expected composition. It does not confirm the order of residues.
Purity
High-performance liquid chromatography (HPLC)
Separates the material from synthesis-related impurities. Purity is reported as the main peak's share of the total detected signal.
Reported per lot. The Oasis Labs specification is 99% or greater.
Quantity
Net content
Measures the mass of material actually present in the sample tested.
Reported per lot on the Certificate of Analysis.
Technical notes
What does the Certificate of Analysis confirm?
Identity by mass spectrometry, purity by HPLC, and the net content of the sample. Mass spectrometry confirms molecular mass, not the order of residues.
Why do molecular weights for LL-37 differ slightly between sources?
The figure of 4493 g/mol is for the form described in the cited PubChem record. Salt forms carry extra counter-ion mass and are often registered separately.
Why is the material freeze-dried?
Peptides are most stable as dry solids. Moisture reduces long-term stability, so the material is lyophilized and kept sealed until use in the laboratory.
LL-37 lot certificates
Each listed LL-37 lot has its own certificate covering identity, purity and net content.
Catalogue entry: LL-37
More from the research reference
References
- National Center for Biotechnology Information. PubChem Compound Summary for CID 16198951 (LL-37). pubchem.ncbi.nlm.nih.gov/compound/16198951. Accessed 20 October 2026.
- MilliporeSigma (Merck KGaA). Handling and storage guidelines for peptides and proteins (technical article). merckmillipore.com. Accessed 14 October 2026.
- Oasis Labs. LL-37 Certificate of Analysis page, lot data and testing laboratories (certificate page), and testing methodology, myoasislabs.com/coa-process/.
References document the chemical identity, analytical characterisation and handling of this material. Molecular composition and the calculated net charge are derived from the published sequence.