Full-length Tβ4 vs the fragment (LKKTETQ) — which is in the vial I'm buying?

N
Joined 2026
28 posts
3/22/2026 · 754 views

Bit of a noob-ish question but I can't find a clear answer. When I buy 'TB-500' from a peptide vendor, am I getting:

  • Full-length Thymosin beta-4 (~43 amino acids, the native peptide)
  • The 17-23 fragment (LKKTETQ, 7 amino acids, the synthetic 'active site' people call TB-500)
  • Something else

Vendor copy is usually vague. Some COAs I've seen specify the fragment. Others just say 'TB-500' with no sequence listed. Should I be insisting on the full-length, or is the fragment the standard community product?

5 Replies

L
Joined 2026
14 posts
3/23/2026

You're almost certainly getting the fragment. 'TB-500' in community parlance has been the 17-23 fragment (LKKTETQ-style) for a decade. Full-length Tβ4 exists (marketed as Thymosin beta-4) and is way more expensive — different product, different price point. If the vendor is charging fragment prices you're getting a fragment.

H
Joined 2025
212 posts
hexaclinicContributor
3/24/2026

Ask for a sequence on the COA. If they can't give you one, walk. 'TB-500' is a trade name, not a sequence specification. A real COA lists what's in the vial.

Q2 stack
  • CJC-1295 no DAC · 100 mcg · pre-bed · sub-Q
  • Ipamorelin · 200 mcg · pre-bed · sub-Q
  • BPC-157 · 500 mcg · 2x/day · sub-Q
S
Joined 2026
117 posts
3/24/2026

Most of the community data, such as it is, is on the fragment. So if you want your experience to map to the forum reports, fragment is what you want. Full-length Tβ4 is a more ambitious purchase with a different literature behind it.

N
Joined 2026
28 posts
3/25/2026

Clarifying, thanks. Going to ask the vendor for the sequence line on the COA before reordering.

F
Joined 2026
20 posts
4/26/2026

Yeah the fragment is standard for 'TB-500' but here's what nobody ever asks, did anyone actually run a proper comparison? Like baseline markers, same person, fragment one cycle then full-length the next with washout in between? Everyone just assumes the fragment is the active site and works, but I've never seen actual data showing it outperforms or matches full-length. Most reports are just anecdotal "felt good" which doesn't tell you much. If you're dropping money on it might be worth getting the COA sequence either way so you at least know what you're running.

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