PHG · REV 2026.10 For laboratory research use only. Not medical or dosing guidance.
Peptide Handling Guide Storage, handling and documentation for research peptides
Document
CS-TB500
Type
Compound handling sheet
Revised
Sources checked
Bands
−20 °C

TB-500 / Thymosin β4 Handling Sheet

Also known as Thymosin beta-4, Tβ4, TMSB4X (gene); "TB-500" in research catalogues

A 43-residue acetylated peptide with a single methionine that oxidizes readily. "TB-500" is used for both full-length thymosin β4 and a short fragment, so confirm which one the COA describes.

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Identity

Sequence
Ac-SDKPDMAEIEKFDKSKLKKTETQEKNPLPSKETIEQEKQAGES
Formula
C212H350N56O78S (full-length thymosin β4)
Molecular weight
4963.4 g/mol (average, full-length)
Usual supplied form
Lyophilized powder
Record
PubChem

M oxidation-prone N deamidation-prone D Asp-Gly / Asp-Ser site

Formula and weight are for the free peptide. Salt forms (acetate, TFA) weigh more; use the figure on the lot's COA.

Storage & sensitivity

Lyophilized−20 °C
In solution−20 °C
Oxidation
High
Light
Low
Moisture
Moderate
Partly documented

Some compound data exists; the rest follows general peptide chemistry.

Bench card

  • Check the COA: "TB-500" may mean full-length thymosin β4 (about 4963 Da) or a short fragment.
  • Met6 oxidizes to the sulfoxide, a +16 Da species that has its own biological activity.
  • Minimize oxygen: degassed solvent, small headspace, inert-gas overlay for long holds.
  • Highly charged and soluble in water; acidic overall.
  • Freeze single-use aliquots; prefer −80 °C for solutions held longer than a few weeks.

Handling-relevant features

FeatureWhy it matters for handling
Met6Oxidizes to methionine sulfoxide (+16 Da); thymosin β4 sulfoxide is a distinct, characterized species
N-terminal acetyl-SerNative modification; the free-amine form is a different molecule
Asn26-Pro27Asn followed by Pro deamidates slowly, so this is a minor site
Gln (Q23, Q36, Q39)Glutamine deamidates much more slowly than asparagine
Many Lys and Glu residuesHighly charged and water-soluble; little aggregation tendency

What it is

Thymosin β4 is a naturally occurring 43-residue, N-terminally acetylated peptide and a major actin-sequestering molecule in cells, reviewed by Goldstein, Hannappel and Kleinman. In research catalogues it is often sold as “TB-500”.

The methionine

Thymosin β4 has a single methionine at position 6. Methionine is readily oxidized to its sulfoxide by dissolved oxygen, peroxides and metal-catalyzed reactions. Young and colleagues showed that thymosin β4 sulfoxide forms in biological conditions and has its own anti-inflammatory activity, which makes oxidation more than a purity issue: an oxidized sample may behave differently in an assay.

Storage

Form Recommended Notes
Sealed powder −20 °C Desiccant; consider inert-gas overlay after opening
Solution, days 2–8 °C Degassed water or buffer; minimal headspace
Solution, weeks or longer −80 °C Single-use aliquots

Analytical notes

Full-length thymosin β4 appears in electrospray spectra as a series of charge states; deconvoluted average mass should be close to 4963 Da. A peak at +16 Da indicates Met oxidation. On reversed-phase HPLC the sulfoxide typically elutes slightly earlier than the parent because it is more polar.

References

  1. Goldstein AL, Hannappel E, Kleinman HK. Thymosin β4: actin-sequestering protein moonlights to repair injured tissues. Trends Mol Med. 2005;11(9):421–429. DOI
  2. Young JD, Lawrence AJ, MacLean AG, et al. Thymosin β4 sulfoxide is an anti-inflammatory agent generated by monocytes in the presence of glucocorticoids. Nat Med. 1999;5(12):1424–1427. PubMed
  3. Li S, Schöneich C, Borchardt RT. Chemical instability of protein pharmaceuticals: mechanisms of oxidation and strategies for stabilization. Biotechnol Bioeng. 1995;48(5):490–500. DOI
  4. Stadtman ER. Oxidation of free amino acids and amino acid residues in proteins by radiolysis and by metal-catalyzed reactions. Annu Rev Biochem. 1993;62:797–821. DOI
  5. Manning MC, Chou DK, Murphy BM, Payne RW, Katayama DS. Stability of protein pharmaceuticals: an update. Pharm Res. 2010;27(4):544–575. DOI

This sheet covers laboratory storage and handling of research material only. It does not describe use in humans or animals, and the supplier's datasheet for your lot takes priority.