Why does LL-37 stick to labware?

Because it is strongly cationic — the sequence is rich in lysine and arginine — and most glass and plastic surfaces carry a net negative charge. Low-concentration solutions can lose a measurable fraction to the container, invisibly.

What is the molecular weight of LL-37?

4493.27 g/mol, formula C205H340N60O53, CAS 154947-66-7. It is a 37-residue peptide derived from the human cathelicidin precursor protein, and its high lysine and arginine content is what governs its handling.

Does LL-37 dissolve easily in water?

Generally yes. Its high positive charge produces strong repulsion between molecules, which keeps them dispersed. The complication is not solubility but adsorption to surfaces and sensitivity to ionic strength.

Identification·2 min read

LL-37 (Cathelicidin) — identity and handling of a cationic peptide

37 residues carrying an unusually high positive charge. That charge governs its solubility, its adsorption to surfaces, and why it needs different labware.

LL-37 is a 37-residue cathelicidin-derived peptide, CAS 154947-66-7, molecular formula C205H340N60O53, molecular weight 4493.27 g/mol. Its defining property is charge: the sequence carries a high proportion of lysine and arginine, which governs its solubility, its adsorption to labware, and how it must be handled.

By the Bench Grade Research Team · Last updated October 7, 2026

LL-37 identity data

Identity
Property	Value
CAS Registry Number	154947-66-7
Molecular formula	C205H340N60O53
Molecular weight	4493.27 g/mol
Length	37 residues
Sequence	LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES

Charge is the whole story

Count the basic residues in that sequence — the lysines and arginines run to double figures against a much smaller count of acidic residues. The result is a strongly cationic peptide at neutral pH, and nearly everything distinctive about handling it follows from that.

Aqueous solubility is generally good, because like charges repel and keep molecules dispersed.
Adsorption to glass and plastic is unusually strong, since most surfaces carry a net negative charge. Low-concentration solutions can lose a meaningful fraction to the container.
Low-binding labware is worth using rather than optional, and pre-rinsing a tip with the solution reduces loss.
The peptide is sensitive to ionic strength: behaviour in plain water and in a salt-containing buffer are not the same.

The amphipathic helix

The sequence folds into a helix with charged residues on one face and hydrophobic residues on the other. That amphipathic arrangement is what the structural literature on this compound concerns, and it is also why the peptide interacts with membranes and with surfaces so readily.

What the published work examined

Four studies in our research library reference this compound, dating from 2003 to 2013. They are laboratory and animal investigations of the peptide's antimicrobial and tissue-model activity, linked below. The work is preclinical.

References

Primary literature for the compounds discussed above. Links open the record on PubMed.

The potential of GHK as an anti-aging peptide Pickart L, et al. Aging Pathobiol Ther. 2022. PMID 35083444 → · summary
Regenerative and Protective Actions of the GHK-Cu Peptide in the Light of the New Gene Data Pickart L, et al. Int J Mol Sci. 2018. PMID 29986520 → · summary
BPC 157 and Standard Angiogenic Growth Factors. Gastrointestinal Tract Healing, Lessons from Tendon, Ligament, Muscle and Bone Healing Sikiric P, et al. Curr Pharm Des. 2018. PMID 29998800 → · summary
The Human Cathelicidin Antimicrobial Peptide LL-37 as a Potential Treatment for Polymicrobial Infected Wounds McCrudden MT, et al. Pharmaceutics. 2013. PMID 23840194 → · summary
A comprehensive summary of LL-37, the factotum human cathelicidin peptide Vandamme D, et al. Cell Immunol. 2012. PMID 22249267 → · summary
The promoting effect of pentadecapeptide BPC 157 on tendon healing involves tendon outgrowth, cell survival, and cell migration Chang CH, et al. J Appl Physiol. 2011. PMID 21030672 → · summary
The cathelicidin anti-microbial peptide LL-37 is involved in re-epithelialization of human skin wounds and is lacking in chronic ulcer epithelium Heilborn JD, et al. J Invest Dermatol. 2003. PMID 12603850 → · summary
Orally Targeted Delivery of Tripeptide KPV via Hyaluronic Acid-Functionalized Nanoparticles Efficiently Alleviates Ulcerative Colitis Xiao B, et al. Mol Ther. 2017. PMID 28456380 → · summary

Primary sources

Frequently asked questions

Why does LL-37 stick to labware?: Because it is strongly cationic — the sequence is rich in lysine and arginine — and most glass and plastic surfaces carry a net negative charge. Low-concentration solutions can lose a measurable fraction to the container, invisibly.
What is the molecular weight of LL-37?: 4493.27 g/mol, formula C205H340N60O53, CAS 154947-66-7. It is a 37-residue peptide derived from the human cathelicidin precursor protein, and its high lysine and arginine content is what governs its handling.
Does LL-37 dissolve easily in water?: Generally yes. Its high positive charge produces strong repulsion between molecules, which keeps them dispersed. The complication is not solubility but adsorption to surfaces and sensitivity to ionic strength.

Compounds discussed in this guide

Who publishes this guide

Who sells it: Bench Grade Peptides LLC, a US supplier of lyophilized synthetic peptides for laboratory research use only. It works with US manufacturing partners rather than running a facility of its own. Is Bench Grade Peptides legit? →
Certificates of Analysis: 139 third-party Certificates of Analysis covering 39 of 44 live products, published per lot in a public library anyone can read before ordering. A very recent lot can appear a few days after it enters the catalogue. COA library →
Ships from: Florida, by UPS, to US addresses only (no international shipping). The registered address in Dover, Delaware is the legal address only. Shipping →
Use: For laboratory research use only — not for human or veterinary use. Not a drug, supplement or medical device. Compliance and research use →

All products discussed in this guide are supplied by Bench Grade Peptides for laboratory research use only. Not for human or veterinary use.