Trinity compound research profile
TB-500 Fragment 17-23
This is the specific, small 7-amino-acid piece called LKKTETQ, cut out from the middle of the larger 43-amino-acid protein thymosin beta-4. Usually it's...
Research overview
This is the specific, small 7-amino-acid piece called LKKTETQ, cut out from the middle of the larger 43-amino-acid protein thymosin beta-4. Usually it's sold with a chemical modification on one end (making it "Ac-LKKTETQ") to help it survive longer in the body. The FDA officially names this exact molecule as "Thymosin beta-4, fragment (LKKTETQ), also known as TB-500" (FDA). Importantly, this is chemically the very same substance that most vendors are actually selling when they use the name "TB-500" — these two catalog entries describe essentially one molecule, not two different things.
Mechanism under study
This 7-amino-acid piece specifically represents the "actin-binding" part of the larger parent protein — meaning it's the section responsible for helping cells grab onto and move around a building-block molecule called actin, which is important for cell movement, new blood vessel formation, and wound healing. However, because it's only this one small piece, it's missing the other parts of the full protein that are responsible for calming inflammation and helping cells survive — so even though it retains the movement/healing-related activity, it does NOT reproduce everything the full-length protein can do (Sosne & Berger 2023).
Human evidence summary
There are no human studies of this fragment specifically. The FDA states plainly that it has not identified any human exposure data for drug products containing this exact fragment (FDA). All the human eye-related clinical trial data that does exist for thymosin beta-4 was actually done using the full-length, 43-amino-acid protein — not this smaller fragment — so that data can't be directly applied here. Reports about faster tendon, ligament, or muscle recovery from this fragment in humans are purely anecdotal, meaning personal stories rather than proven science.
Preclinical evidence summary
The main evidence for this fragment's activity comes from lab studies mapping out which section of the parent protein does what — essentially figuring out that this particular 7-amino-acid stretch is responsible for the movement and healing-related actions. Most of the actual animal experiments studying real wound repair used the full-length protein, not this isolated fragment, meaning there's a gap between "we know this piece theoretically matters" and "we've proven this exact piece works the same as the whole protein in a living animal."
Source material
Use the linked publications and records to evaluate study design, population, limitations, and relevance.