TB-500 — Thymosin-β4 Active-Site Fragment (LKKTETQ)

TB-500 is a synthetic peptide modeled on the short active site within thymosin-β4 (Tβ4), a 43-amino-acid protein found in many tissues. This fragment—Ac-LKKTETQ (Tβ4 residues 17–23)—is studied for its role in cell movement, cytoskeletal organization, and early signals linked to tissue maintenance.

Identifiers

CAS (TB-500): 885340-08-9
Common name: Ac-LKKTETQ (acetyl-Leu-Lys-Lys-Thr-Glu-Thr-Gln)
Molecular formula / weight: C₃₈H₆₈N₁₀O₁₄ · ~889 Da (salt/form dependent)
Related parent protein: Thymosin-β4 (43 aa) — PubChem CID 16132341

How It Works (Plain English)

The 17–23 region of Tβ4 (sequence starting “LKKTET…”) is widely cited as a key actin-binding motif involved in cell movement.
TB-500 focuses on this small region to help researchers isolate cell-migration and cytoskeletal effects without using full-length Tβ4.
It’s explored in models that track early wound-biology signals, such as cell motility and local matrix changes.

Why Researchers Use It

To study cell motility and actin dynamics tied to the Tβ4 active region.
To examine angiogenesis and matrix markers reported with Tβ4-derived sequences.
To compare short-fragment vs full-length peptide behavior in controlled assays.

Key Studies — What Was Tested, What Changed, Why It Matters

Identification of TB-500 as the Tβ4 (17–23) fragment

What was shown: Anti-doping and analytical groups characterized “TB-500” as Ac-LKKTETQ, the 17–23 region of Tβ4.
Why it matters: Confirms the research material corresponds to the short active-site sequence rather than full Tβ4, guiding assay design and dosing models.

Actin/Cell-migration relevance of the LKKTET motif

What was tested: Biochemical and structural studies on Tβ4’s interaction with actin, highlighting the (17)LKKTET(22) motif’s role in actin binding and cell movement.
What changed: Data support Tβ4’s function as an actin-sequestering protein that organizes the cytoskeleton and influences cell motility.
Why it matters: Provides the mechanistic backdrop for using TB-500 to probe motility and early wound-biology pathways at a fragment level.

Pro-repair/anti-fibrotic signals in related Tβ4 fragments

What was tested: Tβ4 and its fragments (e.g., Ac-SDKP) in cardiac and fibrosis models.
What changed: Reports include endothelial migration, anti-fibrotic signaling, and tissue-repair markers (model-dependent).
Why it matters: Although Ac-SDKP is a different fragment, these studies frame the broader repair biology linked to Tβ4-derived sequences.

Design experiments to distinguish TB-500 (Ac-LKKTETQ) effects from those of other Tβ4 fragments like Ac-SDKP.

Potential Research Applications

Cell Motility & Cytoskeleton

Live-cell motility assays; actin imaging
Scratch/wound-closure models in vitro

Angiogenesis & Matrix Microenvironment

Endothelial migration/tube formation
Matrix deposition and remodeling markers

Fragment vs Full-Length Comparisons

TB-500 vs thymosin-β4 head-to-head
Timing, dose, and stability contrasts

Synergistic Peptides (for Study Design)

BPC-157

Why pair: Frequently used in epithelial and microvascular models; complements TB-500’s motility focus.
Angle: Co-culture designs measuring barrier function + migration readouts.

GHK-Cu

Why pair: Copper-dependent ECM/skin remodeling pathways to compare with TB-500’s cytoskeletal signaling.
Angle: Gene-panel and microscopy endpoints (collagen organization + cell motility).

KPV (α-MSH fragment)

Why pair: Often used for inflammatory-signal moderation in epithelial models.
Angle: Cytokine panels + permeability alongside migration assays.

Design Notes

Keep arms distinct (TB-500 alone vs combos), and pre-register endpoints.
Document peptide form (acetate/salt), vehicle, pH, and light exposure—short fragments can be handling-sensitive.
Use controls to separate TB-500 from other Tβ4 fragments (e.g., Ac-SDKP).

Known Concerns (Context)

Naming: “TB-500” refers to the Tβ4 active-site fragment (Ac-LKKTETQ), not full-length Tβ4; verify materials accordingly.
Model variability: Motility/angiogenesis assays are timing- and substrate-sensitive; standardize protocols tightly.
General: Research use only; not for human consumption or therapeutic use.

Specifications & Handling

Form: Lyophilized powder (lot-coded)
Purity: ≥ 99% (HPLC/MS verified)
Storage: ≤ −20 °C; protect from light/moisture

In solution: Aliquot promptly; avoid repeat freeze–thaw
Additives: None unless specified per lot
Packaging: Tamper-evident; research-only labeling

Regulatory & Use Notice

Sold for laboratory research use only. Not for human consumption, medical, or veterinary use. No human-use instructions are provided. Buyer is responsible for safe handling and regulatory compliance.