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Thymosin Beta-4 Fragment Identity — What the Evidence Shows

By Editorial Desk · published 2026-06-21 · last reviewed 2026-08-01 · Wiki

Everything below concerns freeze-thaw. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.

Last reviewed on 2026-08-01. Where a claim depends on a specific study, the study is described rather than over-claimed.

Thymosin Beta-4 Fragment Identity

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.

Detection, Stability, and Regulatory Status

Detection in biological matrices generally relies on liquid chromatography coupled with tandem mass spectrometry, because the peptide lacks a convenient ultraviolet chromophore beyond the amide backbone. Immunoassays have been described, but antibodies raised against the fragment can cross-react with the full-length protein or with unrelated peptides, so findings usually require confirmation by a second technique. Sample preparation typically involves protein precipitation followed by solid-phase extraction. Reported detection windows depend on dose, route, matrix, and instrument sensitivity.

Lyophilised material is stable for extended periods when kept dry and cold, and suppliers typically recommend storage well below freezing. Once dissolved, the peptide is handled at refrigeration temperatures and used within a short period, because peptide bonds and the acetylated terminus can be affected by repeated freeze-thaw cycles, proteases, or extreme pH. Bacteriostatic water and saline are both described as solvents, although preservatives can interfere with some analytical workflows. Reconstituted solutions are inspected for particulates before use.

Tb-500 at a glance

PropertyValueNotes
Molecular massApproximately 4963 Da for full-length thymosin beta-4Value applies to the parent protein; fragment products may differ
AppearanceWhite to off-white lyophilized powderTypical form of supplied synthetic peptide
SolubilityFreely soluble in waterPolar peptide; dissolves readily in aqueous buffer
Storage of dry powder−20 °C, desiccated, protected from lightStandard laboratory practice for peptides
Typical detection methodLiquid chromatography–tandem mass spectrometryUsed in purity testing and anti-doping analysis

Handling, Storage, and Analytical Verification

Storage recommendations center on keeping the dry powder cold, dry, and dark. A freezer at -20 degrees Celsius or below is conventional, and desiccant is often included to limit moisture uptake. Once dissolved, the peptide is less stable, and solutions are typically kept frozen and thawed only once. Repeated freeze-thaw cycles are a common source of losses because they promote aggregation and adsorption to container surfaces. Working aliquots are therefore prepared in advance, and glass or low-binding plastic is usually preferred over ordinary laboratory plastic.

Identity and purity are assessed with a small set of standard techniques. Reverse-phase high-performance liquid chromatography gives a purity estimate from peak area, usually recorded at 214 or 220 nanometers, where the peptide bond absorbs. Mass spectrometry confirms the expected molecular mass and can reveal truncated or oxidized species. Amino acid analysis or tandem mass spectrometry sequencing can verify the sequence itself. Additional quality attributes include water content, residual trifluoroacetic acid carried over from purification, and endotoxin where the material is intended for biological work.

The compound is most often distributed as a lyophilized powder, appearing white to off-white and forming a loose cake or fluffy solid. It is hygroscopic to some degree, so brief exposure to humid air can add water weight and complicate weighing. The peptide dissolves readily in water and in neutral aqueous buffers, and aqueous solubility is generally described as high, well above the concentrations used in typical assays. Some polar organic solvents are also usable, which matters when a concentrated stock is prepared before dilution into buffer.

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Storage and Analytical Verification

Identity and purity are normally assessed with reversed-phase high-performance liquid chromatography, paired with mass spectrometry to confirm molecular mass. A certificate of analysis reports a purity percentage, usually derived from chromatographic peak area, but that figure does not by itself prove a correct sequence or the absence of counterions. Independent verification may include amino acid analysis or peptide mapping. Batch-to-batch variation is a documented concern in the research chemical market, and the gap between a quoted purity value and actual peptide content can be substantial when the material is a salt or retains residual water.

Lyophilized peptide arrives as a dry cake that should stay sealed until use. Reconstitution is generally performed with sterile water or a buffered solution, and the resulting liquid should be handled gently to limit mechanical stress. Repeated freeze-thaw cycles are widely described as harmful to short peptides, so dividing a reconstituted batch into single-use portions is a common practice. Laboratories also record the solvent, concentration, and date of preparation on the vial label to keep later measurements traceable.

Dry powder is commonly held at minus twenty degrees Celsius, with some suppliers recommending lower temperatures for long-term archival storage. Once dissolved, solutions are typically kept cold and protected from light, since aqueous peptide solutions can lose integrity through hydrolysis or oxidation over time. Stability data specific to this fragment are limited in the public literature, and much of the guidance comes from general peptide handling practice rather than from controlled degradation studies. Users therefore treat stated shelf lives as approximate rather than fixed.

Handling, Storage, and Quality Control

Identity and purity are checked with chromatographic and mass spectrometric methods. Reverse-phase high-performance liquid chromatography separates the peptide from related impurities, while mass spectrometry confirms the expected molecular mass. A certificate of analysis may report a purity percentage, but the laboratory should still verify the material independently. Common quality concerns include truncated sequences, deamidation, oxidation, and residual solvents from synthesis. Because TB-500 is short, some impurities can differ from the target by only a few mass units.

Reconstitution practices affect downstream measurements. The dry powder is typically dissolved in sterile water or a suitable aqueous buffer, then mixed gently rather than vortexed at high speed. Visible particles or cloudiness suggest incomplete dissolution or contamination and should be investigated. For long-term storage, aliquots should be labeled with concentration, solvent, and date. Open questions include how different buffers alter peptide conformation and whether specific container materials adsorb the peptide. Those variables can change apparent concentration in assays even when the chemical identity is correct.

Storage, Handling, and Analytical Checks

The regulatory position is broadly consistent across major jurisdictions: no thymosin beta-4 fragment is an approved medicine, and laboratory material is commonly labelled as not intended for human consumption. Anti-doping rules in sport list thymosin beta-4 and its fragments among prohibited peptide hormones. Because these products travel through research-chemical channels rather than pharmaceutical supply chains, quality varies considerably between vendors. Independent testing of identity, purity and sterility is the only dependable check, and a certificate of analysis describes one batch rather than a supplier's whole catalogue.

Lyophilized peptide powder is normally held desiccated at −20 °C, with −80 °C used for longer storage periods. Allowing a sealed vial to reach room temperature before opening is standard practice, because condensation forming on cold powder introduces moisture. Once dissolved, solutions are typically kept cold and shielded from light. Repeated freeze-thaw cycles are avoided because they encourage aggregation and gradual loss of material. These conventions are general to synthetic peptides rather than unique to any one sequence.

Supporting material

There were other witnesses for the defense who did not show up. Several scientists who had been listed as potential witnesses for the state, backed out because of what Clark termed "peer pressure." Another state witness, Dr. Dean Kenyon, a biophysicist at San Francisco State University, mysteriously disappeared on the eve of his day in court. He had flown into Little Rock on a Sunday evening, but when one of Clark's assistants went to take his deposition he could not find him. Kenyon had checked out of the hotel and flown back home. Bird had encouraged Kenyon not to testify, although Kenyon taught evolution theory for 16 years until three years ago when he became a creationist. Bird, who is general counsel to Institute for Creation Research, said he attempted to get other defense witnesses not to testify after he perceived the trial as botched by Clark.

== Diagnosis == Diagnosis of Bruck syndrome must distinguish the association of contractures and skeletal fragility. Ultrasound is used for prenatal diagnosis. The diagnosis of a neonate bears resemblance to arthrogryposis multiplex congenital, and later in childhood to osteogenesis imperfecta.

== Cause == Aside from L. odoratus, other members of the genus are also known to cause the disease, including L. sylvestris, L. cicera, and L. clymenum. L. odoratus grows well under famine conditions, often severe drought, where it is cultivated. These legumes carry a variety of osteolathyrogenic compounds, specifically excitatory amino-compounds. The most widely studied of these compounds is beta-aminopropionitrile (BAPN), which exerts its deleterious effect by an unknown yet potently irreversible mechanism. Other instigators are ureides, semicarbazides and thiosemicarbazides, which are believed to chelate the prosthetic Cu(II)-bipyridine cofactor complex in the enzyme lysyl oxidase. Lysyl oxidase is an important enzyme for the creation of crosslinks between collagen triple-helices in connective tissue. By oxidizing the terminal amino group of lysine, an aldehyde is created. This aldehyde can undergo several reactions with neighboring aldehydes or amines to create strong covalent cross-links between collagen tertiary structures in bone and cartilage. The main product of these reactions is the aldimine compound dehydrohydroxylysinonorleucine. This unique crosslink can be formed by the Schiff base mechanism in which the lone pair of electrons on a primary amine react with the carbonyl carbon of an aldehyde. Other crosslinks include the formation of an α,β-unsaturated ketone via aldol condensation and hydroxylysinonorleucine. If these crosslinks are not formed, as in the case of osteolathyrism, the synthesis of strong mesenchymal and mesodermal tissue is inhibited.

Sources: en.wikipedia.org

Supporting material

Although Liu's family was anxious of their future under communist rule and considered fleeing to Hong Kong, Liu Wenhui encouraged them to stay in China and claimed the new government would treat them well. Mao Zedong appointed Liu as a Vice Chairman of the Southwest Military and Political Committee, where he served until 1954. He was also elected a member of the National Committee of the Chinese People's Political Consultative Conference and a member of the National People's Congress, and was also appointed to the Central Military Commission. In June 1950, his 24th Army was merged with the 62nd Army of the People's Liberation Army. His nephew, Liu Yuanxuan, served as its deputy commander. In 1955, Liu was awarded the Order of Liberation, First Class for his role in the Chinese Civil War.

== Clinical significance == Spontaneous and excessive bleeding can occur because of platelet disorders. This bleeding can be caused by deficient numbers of platelets, dysfunctional platelets, or platelet densities over 1 million/microliter. (The excessive numbers create a relative von Willebrand factor deficiency due to sequestration.) Bleeding due to a platelet disorder or a coagulation factor disorder can be distinguished by the characteristics and location of the bleeding. Platelet bleeding involves bleeding from a cut that is prompt and excessive, but can be controlled by pressure; spontaneous bleeding into the skin which causes a purplish stain named by its size: petechiae, purpura, ecchymoses; bleeding into mucous membranes causing bleeding gums, nose bleed, and gastrointestinal bleeding; menorrhagia; and intraretinal and intracranial bleeding. Excessive numbers of platelets, and/or normal platelets responding to abnormal vessel walls, can result in venous thrombosis and arterial thrombosis. The symptoms depend on the thrombosis site.

Freezing: Using a clear polyester bag, excess air is pushed out and heat sealed with the specimen inside or the specimen can be placed inside polythene bags and sealed with parcel tape. Then it is placed into a normal domestic freezer for at least 14 days at a temperature of −18 °C (0 °F), or for 72 hours if freezing at −30 °C (−22 °F). Anoxia: Small anoxic environments starve the pests of oxygen and are created using sealed barrier films and placing oxygen scavengers and RH buffers inside before sealing. An integrated pest management program is cost-effective over time and the best preventive measure against pests.

=== Hypertension-induced cardiovascular disorders === In a model where FFAR2 and FFAR3 were both deleted, these animals had an exaggerated response to hypertension, with higher fibrosis in the kidney; this was explained by a breakdown in the gut epithelial barrier and activation of the immune system via LPS/TLR4 binding. Studies in humans have found that individuals undergoing hemodialysis using dialysis solutions that contain acetic acid often develop hypotension; the role of FFAR3 in this response, if any, was not investigated. A study of 69 individuals (55.1% women, mean age 59.8 years) found that arterial stiffness was associated with lower levels of FFAR3 and FFAR2 in circulating blood immune cells (particularly regulatory T cells which are known to be protective in murine models of hypertension). Overall, the mouse studies suggest that FFAR3 contributes to suppressing hypertension and its subsequent effects on the heart in mice and that SC-FA-activated FFAR3 and/or FFAR2 may have vasodilatory actions and thereby suppress the development of hypertension and hypertension-induced arterial stiffness in humans. Further studies in humans are needed to investigate the latter possibilities.

Sources: en.wikipedia.org

Notes from published material

CrmA increases infectivity by suppressing its host's inflammatory response through inhibition of IL-1 and IL-18 processing by the cysteine protease caspase-1. In eukaryotes, a plant serpin inhibits both metacaspases and a papain-like cysteine protease.

Calcium dobesilate is a vasoprotective. It is the calcium salt of dobesilic acid. It is a synthetic molecule with the ability to reduce capillary permeability in the body. In Switzerland the drug is sold by the pharmaceutical company OM Pharma under the trade name of Doxium in capsules containing 500 mg of active ingredient.

=== Macro-photography === Macro-scale biological processes, such as the spread of virus infections, can be followed using GFP labeling. In the past, mutagenic ultra violet light (UV) has been used to illuminate living organisms (e.g., see) to detect and photograph the GFP expression. Recently, a technique using non-mutagenic LED lights have been developed for macro-photography. The technique uses an epifluorescence camera attachment based on the same principle used in the construction of epifluorescence microscopes.

=== Hepatocyte growth factor (HGF) === Hepatocyte growth factor (HGF) is a mitogen and insulin tropic agent for the β cell. Inadequate β-cell mass can lead to insulin insufficiency and diabetes. During times of prolonged metabolic demand for insulin, the endocrine pancreas can respond by increasing β-cell mass, both by increasing cell size and by changing the balance between β-cell proliferation and apoptosis. It is important to know the effects of high glucose on the factors that may influence endothelial cell growth. A novel member of endothelium-specific growth factors, hepatocyte growth factor (HGF), is produced in vascular cells. In diabetic patient's, levels of the hepatocyte growth factor (HGF) were found in high levels, thus independently associated with increased the incidence of diabetes. There is a study that indicate that HGF/c-Met signalling is essential for maternal β-cell adaptation during pregnancy and that its absence/attenuation leads to gestational diabetes mellitus. Betatrophin: is a novel protein predominantly expressed in human liver and adipose tissues. Increasing evidence has revealed an association between betatrophin expression and serum lipid profiles, particularly in patients with obesity or diabetes, Thus betatrophin is closely related to diabetes treatment, it promotes greatly the proliferation of pancreatic beta cells, plays an important role in modulating glycolipid metabolism, and maybe replaces insulin in the effective treatment of diabetes.

=== EC 1.14.13 With NADH or NADPH as one donor, and incorporation of one atom of oxygen into the other donor === EC 1.14.13.1: salicylate 1-monooxygenase EC 1.14.13.2: 4-hydroxybenzoate 3-monooxygenase EC 1.14.13.3: Now EC 1.14.14.9, 4-hydroxyphenylacetate 3-monooxygenase EC 1.14.13.4: melilotate 3-monooxygenase EC 1.14.13.5: imidazoleacetate 4-monooxygenase EC 1.14.13.6: orcinol 2-monooxygenase EC 1.14.13.7: phenol 2-monooxygenase EC 1.14.13.8: flavin-containing monooxygenase EC 1.14.13.9: kynurenine 3-monooxygenase EC 1.14.13.10: 2,6-dihydroxypyridine 3-monooxygenase EC 1.14.13.11: Now EC 1.14.14.91, trans-cinnamate 4-monooxygenase EC 1.14.13.12: Now EC 1.14.14.92, benzoate 4-monooxygenase EC 1.14.13.13: Now classified as EC 1.14.15.18, calcidiol 1-monooxygenase EC 1.14.13.14: trans-cinnamate 2-monooxygenase EC 1.14.13.15: Now EC 1.14.15.15, cholestanetriol 26-monooxygenase EC 1.14.13.16: cyclopentanone monooxygenase EC 1.14.13.17: Now EC 1.14.14.23, cholesterol 7α-monooxygenase EC 1.14.13.18: 4-hydroxyphenylacetate 1-monooxygenase EC 1.14.13.19: taxifolin 8-monooxygenase EC 1.14.13.20: 2,4-dichlorophenol 6-monooxygenase EC 1.14.13.21: Now EC 1.14.14.82, flavonoid 3′-monooxygenase EC 1.14.13.22: cyclohexanone monooxygenase EC 1.14.13.23: 3-hydroxybenzoate 4-monooxygenase EC 1.14.13.24: 3-hydroxybenzoate 6-monooxygenase EC 1.14.13.25: methane monooxygenase (soluble) EC 1.14.13.26: Now classified as EC 1.14.18.4, phosphatidylcholine 12-monooxygenase EC 1.14.13.27: 4-aminobenzoate 1-monooxygenase EC 1.14.13.28: Now EC 1.14.14.93, 3,9-dihydroxypterocarpan 6a-monooxygenase EC 1.14.13.29: 4-nitrophenol 2-monooxygenase EC 1.14.13.30: Now EC 1.14.14.94, leukotriene-B4 20-monooxygenase EC 1.14.13.31: 2-nitrophenol 2-monooxygenase EC 1.14.13.32: albendazole monooxygenase EC 1.14.13.33: 4-hydroxybenzoate 3-monooxygenase (NAD(P)H) EC 1.14.13.34: leukotriene-E4 20-monooxygenase EC 1.14.13.35: anthranilate 3-monooxygenase (deaminating) EC 1.14.13.36: Now EC 1.14.14.96, 5-O-(4-coumaroyl)-D-quinate 3′-monooxygenase EC 1.14.13.37: Now EC 1.14.14.97, methyltetrahydroprotoberberine 14-monooxygenase EC 1.14.13.38: anhydrotetracycline monooxygenase EC 1.14.13.39: nitric-oxide synthase EC 1.14.13.40: anthraniloyl-CoA monooxygenase EC 1.14.13.41: Now EC 1.14.14.36, tyrosine N-monooxygenase EC 1.14.13.42: The activity is covered by EC 1.14.13.68, 4-hydroxyphenylacetaldehyde oxime monooxygenase EC 1.14.13.43: questin monooxygenase EC 1.14.13.44: 2-hydroxybiphenyl 3-monooxygenase EC 1.14.13.45: Now EC 1.14.18.2, CMP-N-acetylneuraminate monooxygenase EC 1.14.13.46: (-)-menthol monooxygenase EC 1.14.13.47: Now EC 1.14.14.99, (S)-limonene 3-monooxygenase EC 1.14.13.48: Now classified as EC 1.14.14.51, (S)-limonene 6-monooxygenase EC 1.14.13.49: Now classified as EC 1.14.14.52, (S)-limonene 7-monooxygenase EC 1.14.13.50: pentachlorophenol monooxygenase EC 1.14.13.51: 6-oxocineole dehydrogenase EC 1.14.13.52: Now EC 1.14.14.88, isoflavone 3′-hydroxylase EC 1.14.13.53: Now EC 1.14.14.89, 4′-methoxyisoflavone 2′-hydroxylase EC 1.14.13.54: ketosteroid monooxygenase EC 1.14.13.55: Now EC 1.14.14.98, protopine 6-monooxygenase EC 1.14.13.56: Now EC 1.14.14.100, dihydrosanguinarine 10-monooxygenase EC 1.14.13.57: Now EC 1.14.14.101, dihydrochelirubine 12-monooxygenase EC 1.14.13.58: benzoyl-CoA 3-monooxygenase EC 1.14.13.59: L-lysine N6-monooxygenase (NADPH) EC 1.14.13.60: Now included with EC 1.14.13.100, 25-hydroxycholesterol 7α-hydroxylase EC 1.14.13.61: 2-hydroxyquinoline 8-monooxygenase EC 1.14.13.62: 4-hydroxyquinoline 3-monooxygenase EC 1.14.13.63: 3-hydroxyphenylacetate 6-hydroxylase EC 1.14.13.64: 4-hydroxybenzoate 1-hydroxylase EC 1.14.13.65: deleted EC 1.14.13.66: 2-hydroxycyclohexanone 2-monooxygenase EC 1.14.13.67: Now EC 1.14.14.55, quinine 3-monooxygenase EC 1.14.13.68: Now EC 1.14.14.37, 4-hydroxyphenylacetaldehyde oxime monooxygenase EC 1.14.13.69: alkene monooxygenase EC 1.14.13.70: Now EC 1.14.14.154, sterol 14α-demethylase EC 1.14.13.71: Now EC 1.14.14.102, N-methylcoclaurine 3′-monooxygenase EC 1.14.13.72: Now classified as EC 1.14.18.9, methylsterol monooxygenase EC 1.14.13.73: Now EC 1.14.14.103, tabersonine 16-hydroxylase EC 1.14.13.74: Now EC 1.14.14.85, 7-deoxyloganin 7-hydroxylase EC 1.14.13.75: Now EC 1.14.14.104, vinorine hydroxylase EC 1.14.13.76: Now EC 1.14.14.105, taxane 10β-hydroxylase EC 1.14.13.77: Now EC 1.14.14.106, taxane 13α-hydroxylase EC 1.14.13.78: Now EC 1.14.14.86, ent-kaurene monooxygenase EC 1.14.13.79: Now EC 1.14.14.107, ent-kaurenoic acid oxidase EC 1.14.13.80: Now classified as EC 1.14.14.53, (R)-limonene 6-monooxygenase EC 1.14.13.81: magnesium-protoporphyrin IX monomethyl ester (oxidative) cyclase EC 1.14.13.82: vanillate monooxygenase EC 1.14.13.83: precorrin-3B synthase EC 1.14.13.84: 4-hydroxyacetophenone monooxygenase EC 1.14.13.85: Now EC 1.14.14.135, glyceollin synthase EC 1.14.13.86: The activity is covered by EC 1.14.14.87, 2-hydroxyisoflavanone synthase EC 1.14.13.87: Now EC 1.14.14.140, licodione synthase] EC 1.14.13.88: Now EC 1.14.14.81, flavanoid 3,5-hydroxylase EC 1.14.13.89: Now EC 1.14.14.90, isoflavone 2-hydroxylase EC 1.14.13.90: Now EC 1.14.15.21, zeaxanthin epoxidase EC 1.14.13.91: Now EC 1.14.14.136, deoxysarpagine hydroxylase EC 1.14.13.92: phenylacetone monooxygenase EC 1.14.13.93: Now EC 1.14.14.137, (+)-abscisic acid 8-hydroxylase EC 1.14.13.94: Now EC 1.14.14.138, lithocholate 6β-hydroxylase EC 1.14.13.95: Now included with EC 1.14.14.139, 5β-cholestane-3α,7α-diol 12α-hydroxylase EC 1.14.13.96: Now EC 1.14.14.139, 5β-cholestane-3α,7α-diol 12α-hydroxylase EC 1.14.13.97: Now EC 1.14.14.57, taurochenodeoxycholate 6α-hydroxylase EC 1.14.13.98: Now EC 1.14.14.25, cholesterol 24-hydroxylase EC 1.14.13.99: Now EC 1.14.14.26, 24-hydroxycholesterol 7α-hydroxylase EC 1.14.13.100: Now classified as EC 1.14.14.29, 25/26-hydroxycholesterol 7α-hydroxylase EC 1.14.13.101: senecionine N-oxygenase EC 1.14.13.102: Now EC 1.14.14.141, psoralen synthase EC 1.14.13.103: Now EC 1.14.14.142, 8-dimethylallylnaringenin 2-hydroxylase EC 1.14.13.104: Now EC 1.14.14.143, (+)-menthofuran synthase EC 1.14.13.105: monocyclic monoterpene ketone monooxygenase EC 1.14.13.106: now classified as EC 1.14.15.39, epi-isozizaene 5-monooxygenase. EC 1.14.13.107: limonene 1,2-monooxygenase EC 1.14.13.108: Now EC 1.14.14.144, abieta-7,13-diene hydroxylase EC 1.14.13.109: Now EC 1.14.14.145, abieta-7,13-dien-18-ol hydroxylase EC 1.14.13.110: Now EC 1.14.14.146, geranylgeraniol 18-hydroxylase EC 1.14.13.111: methanesulfonate monooxygenase EC 1.14.13.112: Now EC 1.14.14.147, 3-epi-6-deoxocathasterone 23-monooxygenase EC 1.14.13.113: FAD-dependent urate hydroxylase EC 1.14.13.114: 6-hydroxynicotinate 3-monooxygenase EC 1.14.13.115: Now EC 1.14.14.148, angelicin synthase EC 1.14.13.116: Now EC 1.14.14.174, geranylhydroquinone 3-hydroxylase EC 1.14.13.117: Now EC 1.14.14.39, isoleucine N-monooxygenase EC 1.14.13.118: Now EC 1.14.14.38, valine N-monooxygenase EC 1.14.13.119: Now EC 1.14.14.149, 5-epiaristolochene 1,3-dihydroxylase EC 1.14.13.120: Now EC 1.14.14.150, costunolide synthase EC 1.14.13.121: Now EC 1.14.14.151, premnaspirodiene oxygenase EC 1.14.13.122: chlorophyllide-a oxygenase EC 1.14.13.123: Now EC 1.14.14.95, germacrene A hydroxylase EC 1.14.13.124: now classified as EC 1.14.14.40, phenylalanine N-monooxygenase EC 1.14.13.125: Now EC 1.14.14.156, tryptophan N-monooxygenase EC 1.14.13.126: Now EC 1.14.15.16, vitamin D3 24-hydroxylase EC 1.14.13.127: 3-(3-hydroxyphenyl)propanoate hydroxylase EC 1.14.13.128: 7-methylxanthine demethylase EC 1.14.13.129: Now EC 1.14.15.24, β-carotene 3-hydroxylase EC 1.14.13.130: pyrrole-2-carboxylate monooxygenase EC 1.14.13.131: dimethyl-sulfide monooxygenase EC 1.14.13.132: Now EC 1.14.14.17, squalene monooxygenase EC 1.14.13.133: Now EC 1.14.15.32, pentalenene oxygenase EC 1.14.13.134: Now EC 1.14.14.152, β-amyrin 11-oxidase EC 1.14.13.135: 1-hydroxy-2-naphthoate hydroxylase EC 1.14.13.136: Now EC 1.14.14.87, 2-hydroxyisoflavanone synthase EC 1.14.13.137: Now EC 1.14.14.153, indole-2-monooxygenase EC 1.14.13.138: Now EC 1.14.14.157, indolin-2-one monooxygenase EC 1.14.13.139: Now EC 1.14.14.109, 3-hydroxyindolin-2-one monooxygenase EC 1.14.13.140: Now EC 1.14.14.110, 2-hydroxy-1,4-benzoxazin-3-one monooxygenase. EC 1.14.13.141: Now EC 1.14.15.29, cholest-4-en-3-one 26-monooxygenase [(25S)-3-oxocholest-4-en-26-oate forming] EC 1.14.13.142: Now EC 1.14.15.30, 3-ketosteroid 9α-monooxygenase EC 1.14.13.143: Now EC 1.14.14.76 ent-isokaurene C2/C3-hydroxylase EC 1.14.13.144: Now EC 1.14.14.111, 9β-pimara-7,15-diene oxidase EC 1.14.13.145: Now EC 1.14.14.112, ent-cassa-12,15-diene 11-hydroxylase EC 1.14.13.146: taxoid 14β-hydroxylase EC 1.14.13.147: Now EC 1.14.14.182, taxoid 7β-hydroxylase EC 1.14.13.148: trimethylamine monooxygenase EC 1.14.13.149: phenylacetyl-CoA 1,2-epoxidase EC 1.14.13.150: Now EC 1.14.14.113, α-humulene 10-hydroxylase EC 1.14.13.151: Now EC 1.14.14.84, linalool 8-monooxygenase EC 1.14.13.152: Now EC 1.14.14.83, geraniol 8-hydroxylase EC 1.14.13.153: (+)-sabinene 3-hydroxylase EC 1.14.13.154: erythromycin 12-hydroxylase EC 1.14.13.155: α-pinene monooxygenase EC 1.14.13.156: Now EC 1.14.14.133, 1,8-cineole 2-endo-monooxygenase EC 1.14.13.157: Now EC 1.14.14.56, 1,8-cineole 2-exo-monooxygenase EC 1.14.13.158: Now EC 1.14.14.114, amorpha-4,11-diene 12-monooxygenase EC 1.14.13.159: Now EC 1.14.14.24, vitamin D 25-hydroxylase EC 1.14.13.160: (2,2,3-trimethyl-5-oxocyclopent-3-enyl)acetyl-CoA 1,5-monooxygenase EC 1.14.13.161: (+)-camphor 6-exo-hydroxylase EC 1.14.13.162: Now EC 1.14.14.108, 2,5-diketocamphane 1,2-monooxygenase EC 1.14.13.163: 6-hydroxy-3-succinoylpyridine 3-monooxygenase EC 1.14.13.164: withdrawn: see EC 1.13.11.65, carotenoid isomerooxygenase EC 1.14.13.165: Now classified as EC 1.14.14.47, nitric-oxide synthase (flavodoxin) EC 1.14.13.166: 4-nitrocatechol 4-monooxygenase EC 1.14.13.167: 4-nitrophenol 4-monooxygenase EC 1.14.13.168: indole-3-pyruvate monooxygenase EC 1.14.13.169: Now EC 1.14.18.5, sphingolipid C4-monooxygenase EC 1.14.13.170: pentalenolactone D synthase EC 1.14.13.171: neopentalenolactone D synthase EC 1.14.13.172: salicylate 5-hydroxylase EC 1.14.13.173: Now EC 1.14.14.115, 11-oxo-β-amyrin 30-oxidase EC 1.14.13.174: Now EC 1.14.14.116, averantin hydroxylase EC 1.14.13.175: Now EC 1.14.14.117, aflatoxin B synthase EC 1.14.13.176: Now EC 1.14.14.118, tryprostatin B 6-hydroxylase EC 1.14.13.177: Now EC 1.14.14.119, fumitremorgin C monooxygenase EC 1.14.13.178: methylxanthine N1-demethylase EC 1.14.13.179: methylxanthine N3-demethylase EC 1.14.13.180: aklavinone 12-hydroxylase EC 1.14.13.181: 13-deoxydaunorubicin hydroxylase EC 1.14.13.182: 2-heptyl-3-hydroxy-4(1H)-quinolone synthase EC 1.14.13.183: Now EC 1.14.14.120, dammarenediol 12-hydroxylase EC 1.14.13.184: Now EC 1.14.14.121, protopanaxadiol 6-hydroxylase EC 1.14.13.185: Now EC 1.14.15.33, pikromycin synthase EC 1.14.13.186: Now EC 1.14.15.34, 20-oxo-5-O-mycaminosyltylactone 23-monooxygenase EC 1.14.13.187: L-evernosamine nitrososynthase EC 1.14.13.188: Now EC 1.14.15.35, 6-deoxyerythronolide B hydroxylase EC 1.14.13.189: 5-methyl-1-naphthoate 3-hydroxylase EC 1.14.13.190: Now EC 1.14.14.175, ferruginol synthase EC 1.14.13.191: Now EC 1.14.14.70, ent-sandaracopimaradiene 3-hydroxylase EC 1.14.13.192: Now EC 1.14.14.122, oryzalexin E synthase EC 1.14.13.193: Now EC 1.14.14.123, oryzalexin D synthase EC 1.14.13.194: Now EC 1.14.14.78, phylloquinone ω-hydroxylase EC 1.14.13.195: L-ornithine N5-monooxygenase (NADPH) EC 1.14.13.196: L-ornithine N5-monooxygenase [NAD(P)H] EC 1.14.13.197: Now EC 1.14.14.124, dihydromonacolin L hydroxylase EC 1.14.13.198: Now EC 1.14.14.125, monacolin L hydroxylase EC 1.14.13.199: Now EC 1.14.14.79, docosahexaenoic acid ω-hydroxylase EC 1.14.13.200: tetracenomycin A2 monooxygenase-dioxygenase EC 1.14.13.201: Now EC 1.14.14.126, β-amyrin 28-monooxygenase EC 1.14.13.202: Now EC 1.14.14.127, methyl farnesoate epoxidase EC 1.14.13.203: Now EC 1.14.14.128, farnesoate epoxidase EC 1.14.13.204: Now EC 1.14.14.129, long-chain acyl-CoA ω-monooxygenase EC 1.14.13.205: Now EC 1.14.14.80, long-chain fatty acid ω-monooxygenase EC 1.14.13.206: Now EC 1.14.14.130, laurate 7-monooxygenase EC 1.14.13.207: Now EC 1.14.14.31, ipsdienol synthase EC 1.14.13.208: benzoyl-CoA 2,3-epoxidase EC 1.14.13.209: salicyloyl-CoA 5-hydroxylase EC 1.14.13.210: 4-methyl-5-nitrocatechol 5-monooxygenase EC 1.14.13.211: rifampicin monooxygenase EC 1.14.13.212: 1,3,7-trimethyluric acid 5-monooxygenase EC 1.14.13.213: Now EC 1.14.14.131, bursehernin 5-monooxygenase EC 1.14.13.214: Now EC 1.14.14.132, (–)-4′-demethyl-deoxypodophyllotoxin 4-hydroxylase EC 1.14.13.215: protoasukamycin 4-monooxygenase EC 1.14.13.216: asperlicin C monooxygenase EC 1.14.13.217: protodeoxyviolaceinate monooxygenase EC 1.14.13.218: 5-methylphenazine-1-carboxylate 1-monooxygenase EC 1.14.13.219: resorcinol 4-hydroxylase (NADPH) EC 1.14.13.220: resorcinol 4-hydroxylase (NADH) EC 1.14.13.221: Now EC 1.14.15.28, cholest-4-en-3-one 26-monooxygenase [(25R)-3-oxocholest-4-en-26-oate forming] EC 1.14.13.222: aurachin C monooxygenase/isomerase EC 1.14.13.223: 3-hydroxy-4-methylanthranilyl-[aryl-carrier protein] 5-monooxygenase EC 1.14.13.224: violacein synthase EC 1.14.13.225: F-actin monooxygenase EC 1.14.13.226: acetone monooxygenase (methyl acetate-forming) EC 1.14.13.227: propane 2-monooxygenase EC 1.14.13.228: jasmonic acid 12-hydroxylase EC 1.14.13.229: tert-butyl alcohol monooxygenase EC 1.14.13.230: butane monooxygenase (soluble) EC 1.14.13.231: tetracycline 11a-monooxygenase EC 1.14.13.232: 6-methylpretetramide 4-monooxygenase EC 1.14.13.233: 4-hydroxy-6-methylpretetramide 12a-monooxygenase EC 1.14.13.234: 5a,11a-dehydrotetracycline 5-monooxygenase EC 1.14.13.235: indole-3-acetate monooxygenase EC 1.14.13.236: toluene 4-monooxygenase EC 1.14.13.237: aliphatic glucosinolate S-oxygenase EC 1.14.13.238: dimethylamine monooxygenase EC 1.14.13.239: carnitine monooxygenase EC 1.14.13.240: 2-polyprenylphenol 6-hydroxylase EC 1.14.13.241: 5-pyridoxate monooxygenase EC 1.14.13.242: 3-hydroxy-2-methylpyridine-5-carboxylate monooxygenase EC 1.14.13.243: toluene 2-monooxygenase EC 1.14.13.244: phenol 2-monooxygenase (NADH) EC 1.14.13.245: assimilatory dimethylsulfide S-monooxygenase EC 1.14.13.246: 4β-methylsterol monooxygenase EC 1.14.13.247: stachydrine N-demethylase

Sources: en.wikipedia.org

Frequently asked questions

Is TB-500 the same as thymosin beta-4?

Not necessarily. TB-500 is a commercial label that suppliers apply to synthetic peptides described as thymosin beta-4 or a fragment of it. Published research most often studies the full-length protein, so statements about one do not automatically transfer to the other.

Has any regulator approved TB-500 for medical use?

No. No major regulatory authority lists an approved product under this name, and no pharmacopoeial monograph exists for it. Material sold under the label is therefore supplied outside approved pharmaceutical channels, which affects the quality documentation available.

Why does TB-500 appear in anti-doping literature?

It falls within a prohibited class covering peptide hormones and growth factors, based on presumed effects on tissue repair and blood vessel formation. Anti-doping laboratories have published mass spectrometry methods for detecting thymosin beta-4 related peptides in urine samples.

How is the peptide detected in samples?

The most common approach is liquid chromatography with tandem mass spectrometry after extraction from blood or urine. Immunoassays exist but are generally treated as screening tools because of cross-reactivity.

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