What is the acetyl modification on TB-500?
The N-terminal acetyl modification on TB-500 blocks aminopeptidase cleavage from the N-terminus, extending the compound’s in-vivo stability relative to the unmodified peptide fragment. A standard end-capping modification in peptide engineering.
What the research literature says
N-terminal acetylation replaces the free alpha-amine on the N-terminal amino acid with an acetyl group (CH₃-CO-). The modification serves two purposes: it blocks aminopeptidase enzymes that cleave from the N-terminus, extending the peptide’s in-vivo stability; and it eliminates the positive charge that the free alpha-amine would carry at physiological pH, modestly affecting the peptide’s solubility and interaction profile.
For TB-500 specifically, the acetylation is at the N-terminal leucine of the LKKTETQ binding motif (PMID 11579089 Yarmola actin-binding work). The modification matches the natural N-terminal acetylation present on the parent full-length thymosin β4 protein — TB-500 thus reproduces both the active-site sequence and the N-terminal end-capping of the parent protein.
N-terminal acetylation is one of several end-capping strategies in peptide engineering. C-terminal amidation (replacing the free carboxylic acid with an amide) provides analogous protection against carboxypeptidase cleavage at the C-terminus; combined N-acetylation + C-amidation produces double-end-capped peptides with maximum end-cleavage resistance.
Why this matters in research context
The acetyl modification matters in peptide-research contexts as one of the structural features that distinguishes TB-500 from the unmodified fragment of full-length thymosin β4. Researchers should understand that the acetyl modification is part of the synthetic compound’s stability framework — non-acetylated fragment material would have shorter in-vivo half-life and would not be equivalent to the catalog TB-500 supply.
Related compounds
- TB-500 10mg — the N-acetylated fragment covered by this answer
Related research questions
References
- Yarmola EG et al. Formation and implications of a ternary complex of profilin, thymosin beta 4, and actin. J Biol Chem 2001;276(49):46094-46101. [PMID 11579089]
Research-questions pages describe research-context use of peptide-research terminology. They do not constitute medical, veterinary, or clinical advice. TB-500 is sold strictly as a research-grade reagent for laboratory and bench research applications.