LL-37 (CAS 154947-66-7) is a synthetic 37-amino acid peptide and the sole cathelicidin-derived antimicrobial peptide identified in humans. With a molecular weight of 4493.33 g/mol, LL-37 is defined by the amino acid sequence LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES, a highly cationic, amphipathic alpha-helical peptide derived from the C-terminal cleavage of the 18 kDa precursor protein hCAP-18. Its name reflects the two leucine residues at the N-terminus and its 37-residue length. The amphipathic structure with clustered cationic and hydrophobic faces along the alpha-helix is considered central to its membrane interaction characteristics. Produced via solid-phase peptide synthesis.

LL-37’s amphipathic alpha-helical structure has been characterised as central to its interaction with microbial membranes, and this membrane-active property has been the focus of extensive biophysical and microbiological investigation. In vitro studies have examined its interaction with bacterial membrane model systems, documenting that LL-37 adopts a surface-parallel orientation in oriented lipid bilayers and disrupts the membrane through a toroidal-pore mechanism, with this surface orientation maintained across both anionic and zwitterionic bilayer compositions [1]. Published research characterising LL-37 as a chemoattractant for human neutrophils, monocytes and T cells acting through formyl peptide receptor-like 1 (FPRL1), and documenting calcium mobilisation in FPRL1-transfected cells as evidence of the receptor mediating LL-37’s chemotactic signalling [2], and with in vivo wound-model research documenting that LL-37 accelerates re-epithelialisation and wound closure in a humanised skin wound-healing model engrafted on immunodeficient mice [3], making LL-37 a reference compound in innate-immunity and antimicrobial-peptide research examining membrane-active host defence peptide mechanisms and FPRL1-mediated immunomodulatory signalling in preclinical models.

LL-37 is manufactured in a cGMP compliant laboratory to a guaranteed purity of 98% or above. Every batch is independently tested using HPLC and MS-UPLC analysis before dispatch. Vials are vacuum sealed and stored in a temperature controlled, monitored cold storage system. Certificates of Analysis are available on request.

Sold strictly for in vitro research purposes only. Not for human consumption. Intended for use by qualified researchers in laboratory settings only.

Editorial Team

Dr. Martina Rossi, PhD

Scientific Contributor and Reviewer

Reviewed and approved 14 June 2026

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