Sable · Question
What is the difference between LL-37 and P21?
LL-37 is the 37-residue active fragment of the human cathelicidin hCAP18, studied in antimicrobial-peptide and innate-immunity research (peptide, MW about 4493 g/mol).
Research use only. Not for human consumption. No health claims.
Last verified 2026-10-10
What is the difference between LL-37 and P21?
LL-37 is the 37-residue active fragment of the human cathelicidin hCAP18, studied in antimicrobial-peptide and innate-immunity research (peptide, MW about 4493 g/mol).
Which is heavier, LL-37 or P21?
LL-37 has a molecular weight of about 4493 g/mol and P21 about 578.7 g/mol (PubChem), so LL-37 is heavier by 3,914.3 g/mol, a ratio of 7.76. This means 1 mg of LL-37 contains 222.6 nmol versus 1,728 nmol for P21.
How many mg of P21 are equimolar to 1 mg of LL-37?
1 mg of LL-37 (MW 4493) is 222.6 nmol. The same number of moles of P21 (MW 578.7) weighs 0.1288 mg. Equimolar comparisons matter when testing two compounds side by side in the same assay.
Compare the molecular formulas of LL-37 and P21
PubChem lists LL-37 as C205H340N60O53 (4493 g/mol) and P21 as C27H42N6O8 (578.7 g/mol). LL-37 is a peptide; P21 is a peptidomimetic. These formulas refer to the parent compounds without salt counter-ions.
A 10 mg vial of LL-37 equals how many mg of P21 in moles?
10 mg of LL-37 (MW 4493) is 2.226 µmol. The same amount of P21 (MW 578.7) would weigh 1.288 mg. This equimolar conversion lets two compounds be compared at matched molar amounts in the same experiment.
A 5 mg vial of LL-37 equals how many mg of P21 in moles?
5 mg of LL-37 (MW 4493) is 1.113 µmol. The same amount of P21 (MW 578.7) would weigh 0.644 mg. This equimolar conversion lets two compounds be compared at matched molar amounts in the same experiment.
A 10 mg vial of P21 equals how many mg of LL-37 in moles?
10 mg of P21 (MW 578.7) is 17.28 µmol. The same amount of LL-37 (MW 4493) would weigh 77.64 mg. This equimolar conversion lets two compounds be compared at matched molar amounts in the same experiment.
A 5 mg vial of P21 equals how many mg of LL-37 in moles?
5 mg of P21 (MW 578.7) is 8.64 µmol. The same amount of LL-37 (MW 4493) would weigh 38.82 mg. This equimolar conversion lets two compounds be compared at matched molar amounts in the same experiment.
A CoA for every lot; each vial carries a printed lot number that matches it. Ask with the lot number and we send it.
Cite this
Research use only. Not for consumption. No health claims.
Plain
Sable Peptides. (2026). What is the difference between LL-37 and P21?. UK Research Peptide Reference. Retrieved 11 October 2026, from https://www.sablepeptides.co.uk/questions/compare/ll-37-vs-p21/#sqa-039946
APA
Sable Peptides. (2026, October 11). *What is the difference between LL-37 and P21?*. UK Research Peptide Reference. https://www.sablepeptides.co.uk/questions/compare/ll-37-vs-p21/#sqa-039946
BibTeX
@misc{sable_#sqa-039946_2026,
author = {{Sable Peptides}},
title = {{What is the difference between LL-37 and P21?}},
year = {2026},
howpublished = {\url{https://www.sablepeptides.co.uk/questions/compare/ll-37-vs-p21/#sqa-039946}},
note = {Accessed 11 October 2026. CC BY 4.0}
}Badge
<a href="https://www.sablepeptides.co.uk/ref"><img src="https://www.sablepeptides.co.uk/badge/ref.svg" alt="Data: UK Research Peptide Reference — Sable Peptides" width="220" height="40"></a>
Date modified: 2026-10-10