This is a working overview of Ac-LKKTETQ, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-09-13 and is reviewed periodically as new material appears.
TB-500 is a synthetic peptide whose sequence corresponds to a short fragment near the N-terminus of thymosin beta-4, a small protein present in most mammalian cells. The fragment is commonly cited as containing the actin-binding region of the parent molecule, which is why it appears in laboratory work on cell migration and tissue repair. Suppliers distribute it as a lyophilised powder intended for research use. Its identity is defined by amino acid sequence and by the presence of an acetyl group on the N-terminal residue.
Full-length thymosin beta-4 consists of roughly forty-three amino acids and ranks among the more abundant small proteins in the cytoplasm. The fragment is much shorter, so it cannot reproduce every function attributed to the intact molecule. In cell culture, short actin-binding motifs can interfere with filament dynamics and cell movement, but such observations come from controlled experiments rather than from whole-animal work. Whether a truncated fragment produces the same effects as the parent protein remains an open question.
Interest in the peptide grew during the 2000s and 2010s, when studies of tendon and ligament injuries in horses reported changes in lesion size after treatment. Those reports circulated widely outside the scientific literature and shaped much of the current online discussion. Subsequent reviews noted inconsistent study design, small groups, and a shortage of independent replication. Popular descriptions often blur the line between the fragment, the complete protein, and unrelated growth factors, which complicates comparisons across sources.
The fragment most often associated with the name carries the sequence Ac-LKKTETQ, matching residues 17 through 23 of thymosin beta-4. That region holds the actin-binding motif responsible for much of the parent protein's biochemical activity. Apart from N-terminal acetylation the peptide is unmodified and contains no disulfide bonds, so it shows little ordered secondary structure in solution. Full-length thymosin beta-4 is instead a 43-residue polypeptide of roughly 4.9 kDa found widely across mammalian cell types.
Material sold under this label typically arrives as a freeze-dried powder in a sealed vial with a certificate of analysis. Such certificates usually report reversed-phase chromatography purity plus a mass confirmation, and stated purities commonly sit between 95 and 99 percent. Counter-ion identity, residual trifluoroacetate, water content, and peptide net weight are separate specifications that a certificate may or may not include. A purity figure alone does not establish sequence identity, so independent mass verification remains the practical check.
The designation TB-500 circulates in laboratory and catalog contexts without a single agreed definition. Most product listings apply it to an N-terminally acetylated seven-residue fragment of thymosin beta-4, while other listings attach the same label to the full 43-residue protein. Because the term is commercial rather than systematic, two entries bearing identical names may describe different molecules. Any documentation should therefore state which sequence a given sample is claimed to contain.
| Property | Value | Notes |
|---|---|---|
| Generic designation | Synthetic thymosin beta-4 N-terminal fragment | Peptide nomenclature varies by supplier |
| Peptide length | Approximately 17 amino acid residues | Reported length sometimes differs between sources |
| N-terminal modification | Acetyl group | Affects mass and chromatographic behaviour |
| Compound class | Small synthetic peptide | Not a small-molecule drug |
| Common synonyms | TB4 fragment; thymosin beta-4 fragment | Naming is inconsistent in popular media |
TB-500 is a synthetic heptapeptide with the sequence Ac-LKKTETQ. It corresponds to a short N-terminal region of thymosin beta-4, a 43-amino-acid protein found in many cell types. The fragment contains an actin-binding motif, which is one reason it appears in laboratory studies of cell migration and cytoskeletal dynamics. TB-500 is not the full-length protein and is produced as a research chemical rather than an approved therapeutic agent. Its molecular weight is approximately 889 Da.
Several names appear in scientific and commercial contexts for this peptide. The label TB-500 is informal and does not follow standard biochemical nomenclature. Research articles more often describe the compound as a thymosin beta-4 fragment, Tβ4 fragment, or by its sequence Ac-LKKTETQ. Confusing TB-500 with full-length thymosin beta-4 can lead to incorrect assumptions about activity because the fragment lacks the remaining residues of the parent protein. The relationship between fragment and parent protein remains an active area of study.
Regulatory status differs by country, but TB-500 is not an approved pharmaceutical in major jurisdictions. It is commonly sold as a research chemical for laboratory use, which places responsibility for identity and purity on the supplier and the laboratory. Published human data are limited, and most reports involve preclinical models or cell culture. Questions about whether the fragment mimics all actions of thymosin beta-4, and under which conditions, remain open. Independent verification of any material is therefore a practical requirement in research settings.
Laboratory work on thymosin beta-4 describes binding to monomeric actin and effects on cell migration, angiogenesis, and inflammatory signaling in cultured cells. Animal models have examined skin, corneal, and cardiac repair after injury, with outcomes reported mainly in preclinical literature. Most of that evidence concerns the parent protein rather than preparations labelled TB-500, so extrapolation from animal findings to a specific commercial product remains uncertain. Whether the two behave identically in living systems has not been established in controlled human studies.
No major regulatory agency has approved TB-500 for therapeutic use, and it holds no pharmacopoeial monograph. The name appears on the World Anti-Doping Agency prohibited list within the class covering peptide hormones, growth factors, and related substances. Detection in doping control relies on mass spectrometric methods applied to urine, often after preparation steps that concentrate the analyte. Discussion of TB-500 therefore clusters in biochemistry, sports medicine, and anti-doping literature rather than in registered clinical trials.
TB-500 is a synthetic peptide preparation marketed under a name derived from thymosin beta-4, a 43-residue actin-binding protein first isolated from thymus tissue. The full-length protein has a reported molecular mass near 4963 Da, while material sold as TB-500 is often described as a fragment containing the actin-binding motif LKKTETQ. Because suppliers use the name inconsistently, published sources sometimes refer to the same label as a fragment, a synthetic copy, or a related analog. This naming ambiguity complicates direct comparison of reports across studies.
May 2011 - Single-Cell Mass Cytometry of Differential Immune and Drug Responses Across a Human Hematopoietic Continuum ) Sept 2010 - Highly Multiparametric Analysis by Mass Cytometry Aug 2009 - Mass Cytometry: Technique for Real Time Single Cell Multitarget Immunoassay Based on Inductively Coupled Plasma Time-Of-Flight Mass Spectrometry Sept 2002 - Reaction Cells and Collision Cells for ICP-MS: A Tutorial Review April 2002 - A Sensitive and Quantitative Element-Tagged Immunoassay with ICPMS Detection April 2002 - Detection of Ultratrace Phosphorus and Sulfur by Quadrupole ICPMS with Dynamic Reaction Cell July 2001 - Reaction Chemistry and Collisional Processes in Multipole Devices for Resolving Isobaric Interferences in ICP–MS Aug 2000 - A Dynamic Reaction Cell for Inductively Coupled Plasma Mass Spectrometry (ICP-DRC-MS). Part III. Nov 1999 - A Dynamic Reaction Cell for Inductively Coupled Plasma Mass Spectrometry (ICP-DRC-MS). Part II. Reduction of Interferences Produced within the Cell March 1999 - Theory, Design, and Operation of a Dynamic Reaction Cell for ICP-MS Jan 1995 - Characterization of Ionization and Matrix Suppression in Inductively Coupled ‘Cold’ Plasma Mass Spectrometry June 1992 - Space Charge in ICP-MS: Calculation and Implications July 1988 - Nonspectroscopic Interelement Interferences in Inductively Coupled Plasma Mass Spectrometry A more complete listing of his publications can be found on Google Scholar
=== Absorption === The bioavailability of meloxicam is decreased when administered orally compared to an equivalent IV bolus dose. Different oral formulations of meloxicam are not bioequivalent. Use of oral meloxicam following a high-fat breakfast increases the mean peak drug levels by about 22%; however, the manufacturer does not make any specific meal recommendations. In addition, the use of antacids does not show pharmacokinetic interactions. With chronic dosing, the time to maximum plasma concentration following oral administration is approximately 5–6 hours.
Javed Butler is an American cardiologist and academic, recognized for his contributions to cardiovascular medicine, particularly in heart failure research. He serves as the Maxwell A. and Gayle H. Clampitt Endowed Chair, president, and chief research executive at Baylor Scott & White Research Institute, and senior vice president at Baylor Scott & White Health in Dallas, Texas. He is a fellow of Heart Failure Society of America, European Society of Cardiology, American College of Cardiology, and American Heart Association.
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Knight, the headmaster of Adam and Kristina's charter school (which Julia helped them get approval for). In the final season, Julia has a relationship with Chris, whom she used to date in college, and she works at the law firm where Chris works. But their relationship suffers because she cannot cut ties with Joel. Julia and Joel are able to work things out and mend their relationship and are surprised to learn that Victor's birth mother has given birth to a baby girl with a different men and offers Julia and Joel the chance to adopt her. After an undisclosed amount of time, it is revealed that not long after adopting Victor's sister, Julia gave birth to a son. They are all seen celebrating Christmas together as one big, happy family.
Sources: en.wikipedia.org
It is a synthetic peptide based on a short sequence near the start of thymosin beta-4. It is supplied as a research chemical rather than as a licensed pharmaceutical product.
No. Thymosin beta-4 is the full-length protein of about forty-three amino acids, while the fragment covers only its beginning. The two are related but are not interchangeable in experimental or analytical terms.
The label is a catalogue designation that became common in non-technical discussion. Scientific papers usually refer to the fragment by sequence or as a thymosin beta-4 N-terminal peptide.
Usually not, though usage overlaps. The label most often refers to a short acetylated fragment of the parent protein, while thymosin beta-4 itself is the full 43-residue molecule. Because suppliers vary, a sequence statement is needed to settle the question for any particular lot.