What is LL-37?
LL-37 is a 37-amino-acid peptide cut from the end of human cathelicidin, hCAP18, the only cathelicidin humans make. Named for its first two residues, two leucines, and its length, it is studied for antimicrobial and immune-modulating activity, mostly in cells and animal models. Here is its structure, origin and research.
LL-37 in one table.
| Sequence | LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES |
|---|---|
| Length | 37 amino acids |
| Formula | C205H340N60O53 |
| Molecular weight | 4493.3 g/mol (monoisotopic 4490.575) |
| PubChem CID | 16198951 |
| Source protein | hCAP18, residues 134 to 170 (CAMP gene) |
| Other name | Ropocamptide |
| Status | Research compound; not an approved drug |
Formula and masses from Helion's peptide molecular weight calculator, matching PubChem.
The only human cathelicidin.
Cathelicidins are a family of host-defense proteins with a conserved cathelin domain and a variable antimicrobial tail. Humans have a single cathelicidin gene, CAMP, which encodes an 18 kDa precursor called hCAP18. In neutrophils the precursor is cut by the enzyme proteinase 3, releasing its last 37 residues as LL-37.
A bent amphipathic helix.
In lipid micelles, NMR shows LL-37 folding into a helix-bend-helix across residues 2 to 31, with water-loving and water-avoiding side chains on opposite faces. That amphipathic shape is typical of membrane-active antimicrobial peptides, and the same study mapped a smaller antimicrobial core, KR-12.
Antimicrobial and immune effects in the lab.
In vitro, LL-37 kills a range of bacteria, with activity against some organisms depending on salt concentration, binds bacterial lipopolysaccharide and permeabilizes membranes. It also acts on the immune system: in cells, whole blood and a mouse model it induced chemokines and altered responses to lipopolysaccharide. A 2005 study found that the vitamin D receptor binds a response element in the CAMP promoter, so the active form of vitamin D strongly induced CAMP in human cells, though not in mouse cells.
Not approved.
LL-37 is not an approved drug. Cathelicidin LL-37 was nominated for pharmacy compounding and placed in Category 2, the FDA's group of bulk substances that may present significant safety risks; the nomination was later withdrawn, and the FDA list now shows it among withdrawn nominations, citing nonclinical findings that suggest harm to male reproduction and tumor-promoting effects in some tissues. Helion supplies compounds for laboratory research use only.
Not supplied.
Helion does not supply LL-37. The research library covers the compounds it does supply, each with a reference page and, where issued, an independent report in the COA Portal.
Specs and storage by compound.
Questions (7)
What is LL-37?
A 37-amino-acid peptide released from the human cathelicidin precursor hCAP18, studied for antimicrobial and immune-modulating activity in cells and animal models.
What does LL-37 stand for?
Its first two amino acids, two leucines (LL), and its length, 37 residues.
What is cathelicidin?
A family of host-defense proteins. Humans have one cathelicidin gene, CAMP, whose precursor hCAP18 yields LL-37.
What is the LL-37 sequence?
LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES.
What is the molecular weight of LL-37?
4493.3 g/mol (C205H340N60O53).
How is LL-37 related to vitamin D?
The vitamin D receptor binds a response element in the CAMP gene promoter, and the active form of vitamin D induced CAMP strongly in human cells in a 2005 study.
Does Helion sell LL-37?
No.
Published studies (5)
- The human gene FALL39 and processing of the cathelin precursor to the antibacterial peptide LL-37 in granulocytes
- Structures of human host defense cathelicidin LL-37 and its smallest antimicrobial peptide KR-12 in lipid micelles
- Activities of LL-37, a cathelin-associated antimicrobial peptide of human neutrophils
- The human antimicrobial peptide LL-37 is a multifunctional modulator of innate immune responses
- Human cathelicidin antimicrobial peptide (CAMP) gene is a direct target of the vitamin D receptor and is strongly up-regulated in myeloid cells by 1,25-dihydroxyvitamin D3
Citations from PubMed for reference. They describe the compound in the literature, not any Helion lot, and nothing here is guidance on use.