TB-500 and thymosin beta-4: differences in identity
Full-length TB4 and the Ac-LKKTETQ fragment have different structures. Here is what to check in the sequence, label and cited study.
Hexpeps editorial team · Published: 2026-10-14 · Content reviewed: 2026-10-14 · 3 min read
Quick answer: Are TB-500 and TB4 always the same molecule?
Do not assume they are. Full-length thymosin beta-4 has 43 amino acids; an analytical study of a TB-500 preparation identified the acetylated seven-amino-acid fragment Ac-LKKTETQ. Ask for the exact identity and sequence before comparing references.
An abbreviation can conceal different structures
The literature describes thymosin beta-4 as a peptide of 43 amino acids. Esposito and colleagues identified Ac-LKKTETQ in the TB-500 preparation they analysed in 2012. That identification applies to the material in that study; it does not automatically establish what any shop offers today under the same name.
Comparisons should therefore start with the declared sequence, modifications and form. Copying “TB-500” from two pages is not enough to establish identity.
| Reference | Description in the cited sources |
|---|---|
| Full-length thymosin beta-4 | Peptide of 43 amino acids |
| Ac-LKKTETQ | Acetylated seven-amino-acid fragment identified in the TB-500 preparation studied |
Sources: Mora and colleagues: 43-amino-acid thymosin beta-4 (1997) · Esposito and colleagues: analytical identification of a TB-500 preparation (2012).
What to ask the supplier
Request the reference specification: sequence or unambiguous identity, modifications, expected molecular mass, amount per vial and batch. Compare the identity report with that specification. A method that confirms a mass provides valuable information, but should not be credited with greater structural certainty than it allows.
If the document calls the product “TB4” and the label says “TB-500”, ask for the difference to be resolved in writing. What matters is that the material corresponds to its documentation, not choosing the more familiar abbreviation.
Can results for the full-length molecule be applied to the fragment?
Not automatically. Identify the molecule, formulation and system examined in each paper. A similar name or a relationship between a fragment and the full-length molecule does not prove functional equivalence.
When saving a scientific reference, record which structure was investigated, whether the study was in cells, animals or humans, and what outcome it measured. This helps avoid using evidence about one molecule to make claims about another.
Understanding a study's scope without extrapolating (Spanish)
Comparing BPC-157 and blends
BPC-157 is a separate reference and should be documented separately. If they are offered together, the total amount of the combination does not establish the mass of each component. Ask for the composition and analysis of the blend proposed for delivery.
A complete enquiry avoids ambiguity: specified name and structure, format, number of units and documentation. This guide does not establish clinical equivalence or administration protocols.
Frequently asked questions
Do all shops use TB-500 for the same product?
Do not assume so from the name. Confirm the identity declared by each supplier and that it matches the analysis.
Are 43 amino acids and seven amino acids the same format?
No. They describe different structures, not merely a difference in mass per vial.
Does a TB4 study validate a blend sold as TB-500?
Not on its own. The structure, composition and intervention must match to assess what information is applicable.
Sources consulted
References consulted for this guide. They are not certificates for Hexpeps products or endorsements of our shop.
- Mora and colleagues: 43-amino-acid thymosin beta-4 (1997)
- Esposito and colleagues: analytical identification of a TB-500 preparation (2012)
Conversations that help identify these questions
These are sources of questions, not medical evidence or verification of sellers. Our editorial policy (Spanish) explains the full selection and its limits.
Related catalogue references
Formats and prices per vial, availability and documentation are on each product page.