This is an identity reference. It describes what the designation TB-500 refers to, where the nomenclature is ambiguous, and how the structure behaves analytically. It makes no statement about what the compound does and contains no preparation or handling guidance.
The naming problem, first
TB-500 is a laboratory designation rather than a systematic name, and it is used loosely in this market. It is most commonly applied to a short synthetic fragment corresponding to the actin-binding region of thymosin beta-4, usually residues 17–23, with the sequence Leu-Lys-Lys-Thr-Glu-Thr-Gln (LKKTETQ), frequently supplied N-terminally acetylated.
It is sometimes used, less precisely, as a synonym for full-length thymosin beta-4 itself — a 43-residue peptide. Those are very different materials: different molecular weight, different analytical behaviour and different cost. When ordering, confirm which one a product page is describing. Ours is listed by vial size with its own published analysis, and the sequence is the thing to check rather than the abbreviation.
Structural features that matter analytically
Short and highly polar. A seven-residue sequence with two lysines, a glutamate, two threonines and a glutamine is strongly hydrophilic. Under reverse-phase conditions it retains weakly and elutes early, often near the solvent front. Weak retention makes separation from polar impurities harder, so the method matters: a gradient that starts with very low organic content is doing more work here than one starting higher.
No aromatic residues. As with several short peptides, there is no tryptophan, tyrosine or phenylalanine, so detection at 280 nm is not appropriate and 214 nm is the correct wavelength for a purity assessment.
Two lysines in seven residues. A high proportion of basic sites relative to chain length means proportionally more counter-ion mass. For short, basic peptides the gap between chromatographic purity and net peptide content is often wider than average, and calculating molarity from vial mass and purity alone will overestimate concentration by more than most researchers assume.
N-terminal acetylation. Where present, acetylation adds 42 Da and removes the N-terminal positive charge, which shifts both mass and retention. Acetylated and free-amine versions are distinguishable by mass spectrometry and should not be treated as interchangeable in a record.
Confirming identity independently
Check the sequence against public chemical databases rather than relying on the abbreviation. Our product pages carry compound identity links that run those searches. Given how loosely TB-500 is used across the field, sequence is the only reliable identifier.
What we publish
The compound sits in our extracellular matrix and cell-migration peptides category — a grouping by studied pathway, not by outcome. Each product page carries an independent reverse-phase HPLC analysis, net peptide content, counter-ion form and vial size. Vials carry no batch or lot numbers and are matched to their published test by crimp and cap colour.
Research use only. All products supplied by Battle Born Peptides are laboratory reference materials for in-vitro research and analytical use by qualified professionals. They are not drugs, foods, dietary supplements, cosmetics or medical devices; they are not approved by the FDA or any other regulator for use in humans or animals; and they are not intended to diagnose, treat, cure, mitigate or prevent any disease, or to affect the structure or any function of the body of humans or animals. Nothing in this article is preparation, handling or dosing guidance. See our full research-use terms.