LL-37

The structure of LL-37 in SDS micelles is composed of a curved amphipathic helix-bend-helix motif spanning residues 2–31 followed by a disordered C-terminal tail. The helical bend is located between residues Gly-14 and Glu-16. Similar chemical shifts and 15N nuclear Overhauser effect (NOE) patterns of the peptide in complex with di octanoyl phosphatidylglycerol (D8PG) micelles indicate a similar structure. The aromatic rings of Phe-5, Phe-6, Phe-17, and Phe-27 of LL-37, as well as arginines, showed intermolecular NOE cross-peaks with D8PG, providing direct evidence for the association of the entire amphipathic helix with anionic lipid micelles. The structure of LL-37 serves as a model for understanding the structure and function relationship of homologous primate cathelicidins[5].

LL-37, Human acetate is a 37-residue, amphipathic, cathelicidin-derived antimicrobial peptide, which exhibits a broad spectrum of antimicrobial activity.

L 37 (human) is a 37 amino acid host defense peptide originating from the C-terminal of the human cathelicidin antimicrobial peptide (CAMP, hCAP18). This peptide possesses antimicrobial, antitumor, antiviral, and immunomodulatory properties, along with physiological functions in chemotaxis, wound healing, and angiogenesis. Beyond its antimicrobial capabilities, LL 37 (human) influences various pathways in autoimmune and inflammatory diseases, playing a role in the development of lupus, rheumatoid arthritis, and atherosclerosis. As a binding partner to Aβ42, the expression of LL 37 (human) affects the onset and progression of Alzheimer's disease. Additionally, LL 37 has a notable role in human cancer, promoting tumorigenic effects in ovarian, lung, breast, prostate, pancreatic cancers, and malignant melanoma.

Mammalian AMPs belong to the defensin and cathelicidin families. So far, there is a unique cathelicidin peptide found in 1995 and called human cationic antimicrobial peptide (hCAP18). Its active part starts with double leucine and consists of 37-amino acids at the C-terminus, so which is called LL-37.

LL-37 is an important part of the human immune system, which can resist various pathogens. A plethora of experiments have demonstrated that it has the multifunctional effects of immune regulation, in addition to antimicrobial activity.  Significantly boosts immune function; Fights inflammation; Prevents cancer progression; Accelerates wound healing; Lowers the risk of heart disease; Prevents lung injury; Promotes bone repair.

LL 37 is an antimicrobial peptide derivative of human cathelicidin. Induces FPRL1-mediated chemotaxis of human neutrophils, monocytes and T cells in vitro. Promotes wound healing following skin-targeted electroporation of a plasmid encoding hCAP-18/LL-37 in mice. LL 37 reduces SARS-CoV-2 infection by blocking the receptor binding domain of the S1 spike protein (Kd = 11.2 nM) and by binding to ACE2 (Kd = 25.5.nM). LL 37 inhibits SARS-CoV-2 pseudovirion infection (IC50 = 4.74 μg/mL) in vitro and in vivo. Also triggers apoptosis in colon cancer cells. Cell permeable.

LL-37 side effects are very uncommon. LL-37 induced apparent rosacea symptoms, erythema, and telangiectasia on the skin. Side effects associated with LL-37 may include the following:
Increased inflammation
Induction of autoimmune disease
Depression
Damage to sperm surface membranes

Store at -20°C

[1]Kahlenberg and Kaplan (2013) Little peptide, big effects: the role of LL-37 in inflammation and autoimmune disease. J. Immunol. 191(10) 4895 PMID: 24185823
[2]Bandurska et al (2015) Unique features of human cathelicidin LL‐37. BioFactors 41 289 PMID: 26434733
[3]Chen et al (2018) Roles and Mechanisms of Human Cathelicidin LL-37 in Cancer. Cell Physiol.Biochem. 47 1060 PMID: 29843147
[4]Vierthaler et al (2020) Fluctuating role of antimicrobial peptide hCAP18/LL?37 in oral tongue dysplasia and carcinoma. Oncol. Rep. 44 325 PMID: 32627035
[5]Wang, Guangshun. “Structures of human host defense cathelicidin LL-37 and its smallest antimicrobial peptide KR-12 in lipid micelles.” The Journal of Biological Chemistry 283 47 (2008): 32637–43.