Product description
What is LL-37?
LL-37 is the only antimicrobial peptide from the cathelicidin family found in humans, consisting of 37 amino acids and starting with two leucine residues (hence the name LL-37). The peptide sequence is LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES and its full name is Cathelicidin-related antimicrobial peptide (CAMP).
LL-37 is produced as part of the innate immune system from a larger precursor protein, hCAP18 (human Cationic Antimicrobial Protein 18 kDa). The precursor protein consists of a signal peptide, a cathelin-like domain, and a C-terminal fragment of LL-37. The mature LL-37 peptide is released by proteolytic cleavage by protease 3 in neutrophils or by serine proteases in keratinocytes.
Structurally, LL-37 is an amphophilic peptide - it has both cationic (positively charged) and hydrophobic regions. In aqueous solutions, it adopts an α-helical structure, which is crucial for its biological activity. The molecular weight is approximately 4493 Da. The net positive charge (+6) allows interactions with negatively charged bacterial membranes.
LL-37 is found in many cells, tissues and body fluids, including neutrophils, macrophages, keratinocytes, epithelial cells of the respiratory and gastrointestinal tracts, as well as in sweat, breast milk and seminal fluid. Peptide expression is regulated by vitamin D, linking vitamin D supplementation to antimicrobial immunity.
Mechanism of action
Antimicrobial activity - LL-37 has a broad spectrum of activity against Gram-positive and Gram-negative bacteria, fungi, viruses and parasites. The mechanism involves binding to negatively charged phospholipids of the microbial cell membrane, inserting into the lipid bilayer and forming pores or destabilizing the membrane. Selectivity towards pathogens results from differences in the lipid composition of microbial membranes (more negatively charged lipids) compared to mammalian cells.
Antibiofilm activity - LL-37 has the ability to destroy preformed bacterial biofilms, which distinguishes it from many classic antibiotics. The peptide prevents biofilm formation by inhibiting bacterial adhesion and interfering with intercellular communication (quorum sensing). This activity is particularly important in the context of infected chronic wounds.
PubMed
Bhattacharjya S et al. LL-37: Structures, Antimicrobial Activity, and Influence on Amyloid-Related Diseases. Biomolecules. 2024;14(3):320. PMC
Ramos R et al. Wound healing activity of the human antimicrobial peptide LL37. Peptides. 2011;32(7):1469-1476. PubMed
van Hoek ML. The Human Cathelicidin Antimicrobial Peptide LL-37 as a Potential Treatment for Polymicrobial Infected Wounds. Front Immunol. 2013;4:143. PMC
Heilborn JD et al. The cathelicidin anti-microbial peptide LL-37 is involved in re-epithelialization of human skin wounds and is lacking in chronic ulcerative epithelium. J Invest Dermatol. 2003;120(3):379-389. PubMed
Bandurska K et al. Unique features of human cathelicidin LL-37. Biofactors. 2015;41(5):289-300. PubMed
Nagaoka I et al. Cathelicidin family of antibacterial peptides CAP18 and CAP11 inhibit the expression of TNF-alpha by blocking the binding of LPS to CD14(+) cells. J Immunol. 2001;167(6):3329-3338. PubMed
Tokumaru S et al. Induction of keratinocyte migration via transactivation of the epidermal growth factor receptor by the antimicrobial peptide LL-37. J Immunol. 2005;175(7):4662-4668. PubMed
Overhage J et al. Human host defense peptide LL-37 prevents bacterial biofilm formation. Infect Immun 2008;76(9):4176-4182. PMC
Wang G et al. Design of Antimicrobial Peptides: Progress Made with Human Cathelicidin LL-37. Adv Exp Med Biol. 2019;1117:215-240. PubMed
