LL-37 vs Thymosin Alpha-1
LL-37 (Cathelicidin antimicrobial peptide) and Thymosin Alpha-1 (Immunomodulatory peptide (thymic)) are documented as co-studied in the PeptiDex library. This page puts the two entries side by side on class, molecular weight, half-life, origin, mechanism and studied research areas — every value taken from the entry it belongs to.
Why these two are co-studied
Cross-referenced for research context — not a usage or combination recommendation.
At a glance
| Attribute | LL-37 | Thymosin Alpha-1 |
|---|---|---|
| Compound class | Cathelicidin antimicrobial peptide | Immunomodulatory peptide (thymic) |
| Research category | Healing & Recovery | Longevity & Cellular |
| Length (amino acids) | 37 amino acids | 28 amino acids |
| Molecular weight | ~4493 Da | 3108 g/mol (approx.) |
| Half-life | Not documented | ~2 hours (circulating) |
| Origin | LL-37 is a naturally occurring human antimicrobial peptide, the active fragment released from the C-terminal region of the human cathelicidin precursor protein hCAP18. It is part of the innate immune system and is expressed by neutrophils and various epithelial cells. | Thymosin alpha-1 (Thymalfasin) is a 28-amino-acid peptide originally isolated from thymosin fraction 5 of thymic tissue and later produced synthetically. It corresponds to a fragment of the precursor protein prothymosin alpha and is naturally acetylated at its N-terminus. |
“Not documented” means the PeptiDex entry records no value for that field. Nothing on this page is estimated, and no figure is carried over from one compound to the other.
How LL-37 works
LL-37 is a cationic, amphipathic host-defense peptide that can disrupt microbial membranes, giving it broad antimicrobial activity. Beyond direct killing, it has immunomodulatory roles, including chemotactic effects on immune cells, modulation of inflammatory signaling, and reported influence on angiogenesis and wound healing. These roles are documented in in-vitro and animal studies as part of innate immunity.
How Thymosin Alpha-1 works
Thymosin alpha-1 acts as an immunomodulator, reported to enhance T-cell maturation and function, influence dendritic cell activity, and modulate innate immune signaling including Toll-like receptor pathways. It has been studied for augmenting responses to antigens and vaccines and for regulating immune responses in infection and cancer contexts. Its effects are attributed to broad immune-regulating activity rather than a single narrowly defined receptor.
Mechanistic descriptions reflect published research-literature understanding and are quoted from each compound's own entry. Much peptide research is preclinical (in-vitro or animal-model); mechanism in humans may differ and is not established for many compounds.
Where each one appears in the literature
The research contexts each entry documents. Listing a research area is not a claim of efficacy or a therapeutic indication, and the two lists are not scored against each other.
LL-37
Thymosin Alpha-1
What sets each apart
LL-37
LL-37 is unique in this group as a natural host-defense peptide combining direct antimicrobial activity with immune modulation, rather than being a synthetic repair-focused peptide.
Thymosin Alpha-1
Thymosin alpha-1 is a single, well-characterized synthetic peptide with genuine clinical trial data and approvals in some countries, unlike the research-only thymic fraction Thymalin.
Frequently asked questions
What is LL-37?
LL-37 is the sole human cathelicidin antimicrobial peptide, a 37-amino-acid amphipathic alpha-helical peptide released from the C-terminal region of the hCAP18 precursor. It is named for its two leading leucine residues and its length. It functions in the innate immune system as a first-line defense at sites of infection, inflammation, and wounds.
What is LL-37 studied for?
Research examines LL-37 for direct antimicrobial activity against bacteria, and for antiviral, immunomodulatory, angiogenic, and wound-healing roles. Multiple patents describe LL-37 and its derivatives for wound healing. It is also studied in the context of inflammatory and autoimmune conditions, where it can present nucleic acids to immune receptors.
How does LL-37 kill microbes?
As a cationic, amphipathic alpha-helix, LL-37 interacts with and disrupts negatively charged microbial membranes, permeabilizing them. This membrane-targeting mechanism makes broad resistance harder to develop than with conventional antibiotics, which is a key reason it is studied as an antimicrobial-peptide template.
What is thymosin alpha-1?
Thymosin alpha-1 (Ta1, thymalfasin, brand Zadaxin) is an acetylated 28-amino-acid thymic peptide that acts as an immunomodulator. It is studied for enhancing T-cell maturation and dendritic-cell function, in part through Toll-like receptor signaling (TLR9/TLR2).
What is the sequence and molecular weight of thymosin alpha-1?
Its sequence is Ac-SDAAVDTSSEITTKDLKEKKEVVEEAEN, a 28-residue N-acetylated peptide with a molecular weight of about 3108 Da. The N-terminal acetylation is a defining structural feature of the native molecule.
Is thymosin alpha-1 an approved drug?
Thymosin alpha-1 is approved as Zadaxin (thymalfasin) in more than 30 countries, chiefly for chronic hepatitis B and as an immune adjunct, but it is not FDA-approved in the United States. This makes it a research chemical in the US context.
Answers are the ones published on each compound's own PeptiDex entry. They are educational summaries of research-literature context and are not medical advice.