OnePin Peptide Library · Repair & Recovery
TB-500 FRAG
TB-500 Fragment · T-Beta-4 Fragment · AC-LKKTETQ
TB-500 FRAG (also called TB4 Active Site, Thymosin β-4 Fragment, or LKKTETQ peptide) is the synthetic 7-amino-acid active site peptide of Thymosin Beta-4 (Tβ4 / TB-500), corresponding to the central actin-binding region (residues 17-23 of the 43-residue parent) - sequence Leu-Lys-Lys-Thr-Glu-Thr-Gln. The full TB-500 / Tβ4 molecule has multiple bioactive regions: actin-binding (this fragment), N-terminal acetylated dipeptide (Ac-SDKP, an angiogenic / anti-fibrotic motif), and a C-terminal region implicated in cell migration. The isolated active-site fragment retains the actin-sequestering / tissue-migration activity but lacks the parent molecule's N-terminal anti-fibrotic motif and overall systemic profile.
Inject any time of day. Reconstitute with bacteriostatic water; refrigerate. Can be co-injected with BPC-157 in the 'Wolverine stack' since both are linear peptides without Met/Cys conflicts. Daily dosing typical given the shorter half-life vs full TB-500.
Start here. Every protocol below is ordered lowest-first. Begin at the smallest effective dose, hold about a week to assess tolerance, and step up only if needed.
How it works
TB-500 FRAG (LKKTETQ) is the actin-binding active site of Thymosin β-4. The full Tβ4 protein is the most abundant intracellular actin-sequestering peptide in vertebrates, regulating G-actin pool availability for cytoskeletal dynamics. The isolated active site retains key elements of this function:
Actin Sequestering
Binds G-actin monomers, regulating the G-actin / F-actin equilibrium that governs cell shape, migration, and division. This is the primary biochemical action.
Cell Migration
Modulation of actin dynamics is required for cell migration to injury sites - keratinocytes for wound closure, endothelial cells for revascularization, immune cells for inflammation resolution.
Pro-Angiogenic
Tβ4 (and to lesser extent the active-site fragment) promotes endothelial cell migration and tube formation - basis of pro-angiogenic activity in cardiac and dermal repair contexts.
Anti-Inflammatory
Modulates NF-κB signaling and reduces inflammatory cytokine production at injury sites.
Smaller Molecule Advantage
7 vs 43 amino acids - faster synthesis, lower cost, theoretically better tissue penetration. Trade-off: lacks the parent molecule's N-terminal Ac-SDKP anti-fibrotic motif, which is a separately bioactive segment of full TB-500.
No Met or Cys
Linear peptide without sulfur-containing residues - chemistry-compatible with copper-conjugated peptides like GHK-Cu. Wolverine-stack-friendly.
What to expect
Week 1-2: subjective improvements possible in acute injury contexts.
Week 4-6: peak tissue repair activity in acute injury.
Week 8-12+: chronic injury contexts may require longer cycles.
Evidence
Interactions & stacking
What's safe to combine, and what belongs in a separate pin.
Keep separate
Side effects & safety
Commonly reported
- Injection site reaction (mild)
- Mild fatigue (early doses, rare)
- Mild headache (early doses)
Less common & notes
- Theoretical concerns about cell migration / angiogenesis enhancers in users with active malignancy.
- Long-term safety beyond research-chemical community use is uncharacterized.
- Allergic reactions to peptide are rare.
- Manufacturer purity varies - low-quality vendors may include contaminants that drive injection-site reactions.
Pharmacokinetics
Storage. Lyophilized vial: refrigerate (2-8°C / 36-46°F) or freeze (-20°C) for long-term storage. After reconstitution with bacteriostatic water: refrigerate, use within 21-28 days. Light-sensitive. Discard if cloudy, discolored, or beyond use-by window.
Regulatory status
Not FDA-approved for any indication. Has not entered Phase 1 clinical trials in isolation (full TB-500 has had limited clinical work). Available only as research chemical from peptide-supply vendors. WADA prohibited under class S2 (peptide hormones, growth factors) by Tβ4-family classification. Sale for human use is prohibited by FDA regulation.
Put it to work
Calculate, log & track
Open TB-500 FRAG straight into OnePin with your vial and dose pre-filled, then let it handle the syringe math and remind you before the vial runs out.
Open TB-500 FRAG in the app →Go deeper
The guide & community
The complete TB-500 FRAG walkthrough, real protocol discussion and coaching live inside the BlessUp community on Skool.
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