Cathelicidin-family peptide
LL-37
LL-37 is a product of the processing of human hCAP-18. Detecting the precursor does not establish the presence of free LL-37. Its literature addresses proteolytic processing and interactions with microbial membranes.
This is a research reference, not a product offered in the Asciende catalog. Published studies do not establish the identity, purity or availability of a commercial preparation.
Activity in a model and assay conditions
Separate result and explanation. Activity under particular conditions does not define a specification for every material using the same name.
- Does the observation come from a cellular system, microorganism or whole organism?
- Are vehicle, medium and controls that may change the readout reported?
- Does the observed marker demonstrate the proposed mechanism or merely remain compatible with it?
Mechanism described in the literature
In in vitro Candida albicans experiments, LL-37 remained associated with the cell wall and membrane and produced extensive membrane changes. These fungal observations do not establish a universal mechanism against every pathogen.
Other names in the literature
- Cathelicidin LL-37
Where processing occurs
A human neutrophil study found hCAP-18 and granular proteins together in the phagolysosome, but did not detect the expected processing there. Proteinase 3 generated LL-37 in material released by exocytosis. Spatial coincidence of a precursor and an enzyme therefore does not, by itself, demonstrate that the reaction occurred (PMID 11389039).
Similar readouts can arise through different routes
LL-37 and histatin 5 both caused nucleotide efflux in Candida experiments, but differed in localization and membrane damage. LL-37 caused extensive membrane disorganization, whereas histatin 5 accumulated intracellularly. Measuring extracellular ATP alone would conceal that distinction (PMID 15707390).
Identify the material before interpreting activity
A precursor, a processed peptide and a preparation containing additional components are different materials. The term cathelicidin may identify a family or a precursor. An immunological signal or antimicrobial activity alone cannot resolve the preparation's molecular identity.
Questions and answers
Are LL-37 and hCAP-18 interchangeable names?
No. LL-37 is a processed product and hCAP-18 is its precursor. Results must be attributed to the material actually identified in the experiment.
Does ATP release identify the mechanism?
Not by itself. In the cited comparison, microscopy and localization provided information that extracellular ATP measurements alone could not supply.
Sources
- Human cathelicidin, hCAP-18, is processed to the antimicrobial peptide LL-37 by extracellular cleavage with proteinase 3. — Blood, 2001
- Human cathelicidin, hCAP-18, is processed to the antimicrobial peptide LL-37 by extracellular cleavage with proteinase 3.
- Candidacidal effects of two antimicrobial peptides: histatin 5 causes small membrane defects, but LL-37 causes massive disruption of the cell membrane. — Biochem J, 2005
- Candidacidal effects of two antimicrobial peptides: histatin 5 causes small membrane defects, but LL-37 causes massive disruption of the cell membrane.