Almost all organisms, from insects to humans, produce short peptides with antimicrobial activity. They usually carry a positive charge and a hydrophobic part: the charge draws them to microbial membranes, which are negatively charged, and the hydrophobic part lets them insert into and destabilise those membranes.
In humans there are two major families: the defensins and the single cathelicidin, whose active fragment is LL-37, named for starting with two leucines and having 37 amino acids. It is produced in neutrophils, the skin and the mucosa.
Their role goes beyond killing microbes: LL-37 attracts immune cells, influences wound healing and modulates inflammation, protectively in some contexts and amplifying it in others. That double nature means research on it calls for careful analysis of the experimental model.
Interest in these peptides is growing because of antibiotic resistance, since microbes find it harder to develop resistance to a membrane-damaging mechanism. Most studies are still preclinical.
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Learn it in depth at the Peptide University
- Antimicrobial peptides of innate immunity · Module 12
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Definition for educational and scientific purposes. It is not medical advice or a recommendation for use. NeoPeptidos products are sold labelled for research use only (RUO).