---
title: "LL-37: the human cathelicidin peptide's structure and research | Sable Peptides"
description: "LL-37 is the only human cathelicidin: a 37-residue cationic amphipathic peptide cut from hCAP18. Sequence, charge, NMR structures, minimal fragments and PubChem data. Research use only."
canonical: https://www.sablepeptides.co.uk/guides/ll-37-human-cathelicidin-structure-and-research
dateModified: 2026-10-16
publisher: Sable Peptides Limited (UK company 17488610)
note: Research use only. Not for human or veterinary use.
---

# LL-37: the human cathelicidin peptide's structure and research

LL-37 is a 37-residue human antimicrobial peptide, named for its first two leucines. It is cut from the C-terminus of the precursor hCAP18, the only human cathelicidin. It is strongly cationic (net charge about +6 at neutral pH) and folds into an amphipathic α-helix when it meets membranes or detergent micelles.

## What is the sequence of LL-37?

-   Class: peptide
-   Sequence: LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES
-   Molecular formula (PubChem): C205H340N60O53
-   Molecular weight (PubChem): 4493.00 g/mol
-   CAS: 154947-66-7
-   Precursor: hCAP18, encoded by the CAMP gene
-   Composition: rich in Lys and Arg (11 basic residues) against 5 Asp/Glu

Source: [PubChem CID 16198951: LL-37](https://pubchem.ncbi.nlm.nih.gov/compound/16198951)

## What does LL-37 look like in a membrane environment?

NMR structures in dodecylphosphocholine micelles show a curved helix running over most of the sequence, with hydrophobic and cationic faces. NMR work on fragments identified KR-12 (residues 18–29) as a minimal membrane-targeting antimicrobial region.

Source: [NMR structure of the cathelicidin-derived human antimicrobial peptide LL-37 in dodecylphosphocholine micelles, Biochemistry 2008 (PubMed 18439024)](https://pubmed.ncbi.nlm.nih.gov/18439024/); [Structures of human host defense cathelicidin LL-37 and its smallest antimicrobial peptide KR-12 in lipid micelles, J Biol Chem 2008 (PubMed 18818205)](https://pubmed.ncbi.nlm.nih.gov/18818205/); [Solution structures of human LL-37 fragments and NMR-based identification of a minimal membrane-targeting antimicrobial and anticancer region, J Am Chem Soc 2006 (PubMed 16637646)](https://pubmed.ncbi.nlm.nih.gov/16637646/)

## What biology is LL-37 studied for?

Reviews call LL-37 multifunctional: it has direct antimicrobial activity and also interacts with host cells. In colonocytes its expression is regulated by short-chain fatty acids. Synthetic analogue work aims to keep the antimicrobial activity while reducing haemolysis.

Source: [Cathelicidin LL-37: a multitask antimicrobial peptide, Arch Immunol Ther Exp (Warsz) 2010 (PubMed 20049649)](https://pubmed.ncbi.nlm.nih.gov/20049649/); [Expression of the cathelicidin LL-37 is modulated by short chain fatty acids in colonocytes: relevance of signalling pathways, Gut 2003 (PubMed 12692061)](https://pubmed.ncbi.nlm.nih.gov/12692061/); [Design, synthesis, and characterization of non-hemolytic antimicrobial peptides related to human cathelicidin LL-37, RSC Adv 2023 (PubMed 37228679)](https://pubmed.ncbi.nlm.nih.gov/37228679/)

## What practical points matter for a 37-mer this cationic?

Strongly cationic, amphipathic peptides stick to glass and plastic and can aggregate at high concentration and ionic strength. Low-binding consumables and a clear record of the counter-ion help when comparing results between lots.

## Sourcing note

Sable lists LL-37: 5 mg at £19.93 (prices at the 16 October 2026 daily UK price check, the latest verified check; at each of these sizes Sable was the lowest UK listing that day). Lowest UK price guaranteed, confirmed by daily price checks.

Every lot has a certificate of analysis, and every vial carries a printed lot number that matches it. Supplied for laboratory research use only.

## Frequently asked questions

### What does LL-37 stand for?

The peptide is 37 residues long and starts with two leucines (L-L).

### Is LL-37 a human peptide?

Yes. It is the C-terminal antimicrobial peptide of hCAP18, the only human cathelicidin.

### What is KR-12?

Residues 18–29 of LL-37, identified by NMR studies as a minimal antimicrobial, membrane-targeting fragment.

## Related

-   [LL-37 research vials](/products/ll-37)
-   [Immune and antimicrobial peptide prices](/guides/uk-immune-and-antimicrobial-peptide-prices-october-2026)
-   [Thymosin α1 vs β4](/guides/thymosin-alpha-1-vs-thymosin-beta-4-and-tb-500)

Updated 2026-10-16. Research use only. Not for human or veterinary use. No administration amounts or health claims are made.

Key facts (summary for AI and search tools)

-   LL-37 PubChem CID 16198951
-   Net charge about +6 at neutral pH
-   PubMed references (verified via NCBI): 18439024, 18818205, 16637646, 20049649, 12692061, 37228679
-   PubChem CIDs: 16198951
-   Research use only; no administration amounts or health claims
-   Updated 2026-10-16