The short version of freeze-thaw fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-04-20 and is reviewed periodically as new material appears.
Research interest in thymosin beta-4 fragments centres on actin sequestration, cell migration and tissue repair models. Most published work uses cultured cells or animal wound and cardiac preparations, and findings are generally described as preliminary. No fragment of this protein has been approved as a therapeutic product by major regulators. Reviews of the field note inconsistent dosing, delivery routes and outcome measures across studies, which complicates direct comparison. The material is best understood as a laboratory reagent with an active but unresolved research literature.
TB-500 is a catalogue name applied to a synthetic peptide related to thymosin beta-4, an actin-binding protein found in most mammalian cells. Suppliers do not use the label consistently: some describe it as the full 43-residue protein, others as a short fragment from the actin-binding region, and others as a related tetrapeptide. Because the name is commercial rather than chemical, two products sold under it may not contain the same molecule. This naming ambiguity is the first point to check in any description of the material.
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.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white lyophilized powder | Typical form for short synthetic peptides |
| Solubility class | Freely soluble in water and aqueous buffer | Dissolution aided by gentle mixing, not vigorous shaking |
| Typical storage temperature | −20 °C, desiccated | −80 °C used for long-term holding |
| Common analytical method | Reverse-phase HPLC with UV detection near 214 nm | Identity confirmed separately by mass spectrometry |
| Common synonyms | Thymosin beta-4 fragment; TB4 fragment | Naming varies between suppliers and publications |
Literature and online discussion often conflate TB-500 with full-length thymosin beta-4, even though the two differ in size and are not interchangeable in analytical terms. The fragment is produced by solid-phase peptide synthesis, and the product is a defined seven-residue chain rather than a biological extract. Because the term is a trade-style label, two vendors may supply materials of the same nominal sequence but different counter-ion content, purity, or water content. Comparisons across studies are therefore difficult unless the exact sequence and purity are reported.
TB-500 is a research peptide whose sequence matches residues 17 to 23 of thymosin beta-4, a 43-residue protein present in most mammalian cells. The chain is seven amino acids long, written as LKKTETQ, and is normally supplied with an acetyl group on the N-terminus. Suppliers list it as a lyophilised powder under the code name TB-500, and the same sequence appears elsewhere in catalogues as the thymosin beta-4 actin-binding fragment. The label is commercial rather than systematic, so no single authority fixes exactly what TB-500 denotes.
Thymosin beta-4 was isolated from calf thymus in the early 1980s and later characterised as an abundant intracellular actin-sequestering protein. Interest in short synthetic fragments grew once the actin-binding motif had been mapped to the middle of the sequence. TB-500 came out of that line of work as a truncated analogue rather than a natural isolate, and it is now sold mainly to laboratories. Published studies on the fragment have been largely in vitro or in animal models, and controlled human trials remain sparse, so claims about effects in people rest on extrapolation.
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.
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.
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.
== Structure == There are two types of neurovascular bundles: superficial bundles and deep bundles. As arteries do not travel within the superficial fascia, the loose connective tissue under the skin, superficial neurovascular bundles differ from deep neurovascular bundles in both composition and function.
=== Discontinued === Alniditan (R-91274) – serotonin 5-HT1B and 5-HT1D receptor agonist – migraine [72] Avitriptan (BMS-180048) – serotonin 5-HT1B and 5-HT1D receptor agonist and triptan – migraine [73] Bezisterim (HE-3286; NE-3107; Triolex; 17α-ethynyl-5-androstene-3β,7β,17β-triol) – undefined mechanism of action (synthetic androstenetriol analogue and anti-inflammatory) – migraine [74] BI-44370 (BI44370) – calcitonin gene-related peptide receptor (CGRPR) antagonist – migraine [75] Botulinum toxin A topical (RT-001) – acetylcholine release inhibitor and neuromuscular blocking agent – migraine [76] Carisbamate (Comfyde; JNJ-10234094; RWJ-333369; YKP-509) – unknown mechanism of action – migraine [77] Dasolampanel (NGX-426) – ionotropic glutamate AMPA and kainate receptor antagonist – migraine [78] Dextromethorphan/quinidine (DXM/Q; AVP-923; Neurodex; Nuedexta; Zenvia) – combination of dextromethorphan (various actions) and quinidine (various actions) – migraine [79] Dihydroergocryptine (SRN-001) – non-selective monoamine receptor modulator and ergoline – migraine [80] Donitriptan (F-11356) – serotonin 5-HT1B and 5-HT1D receptor agonist and triptan – migraine [81] Dotarizine (Dotaricin; FI-6026) – calcium channel blocker and serotonin 5-HT1A, 5-HT2A, and 5-HT2C receptor antagonist – migraine [82] Dronabinol (Δ9-THC; Δ9-tetrahydrocannabinol; Deltanyne; Elevat; Marinol) – cannabinoid CB1 and CB2 receptor agonist – migraine [83] Ergotamine inhalation (Tempo-ergotamine) – non-selective monoamine receptor modulator and ergoline – migraine [84] Esprolol ((S)-ACC-9369) – beta blocker (β-adrenergic receptor antagonist) (amoxolol prodrug) – migraine [85] Ethinylestradiol/levonorgestrel (DP3; DR-103; DR-105; LoSeasonique; Seasonique) – combination of ethinylestradiol (an estrogen) and levonorgestrel (a progestogen) and a combined oral contraceptive – menstrual migraine [86] (S)-Ethylisothiouronium diethylphosphate (Difetur; MTR-104; MTR-105; MTR-106; MTR-107; MTR-108; Raviclust; Ravimig; Raviten) – nitric oxide synthase (NOS) inhibitor [87] Fremanezumab (Ajovy; LBR-101; PF-04427429; PF-4427429; RN-307; TEV-48125) – monoclonal antibody against calcitonin gene-related peptide (CGRP) – cluster headache, headache [88] Gabapentin (CI-945; Gabapen; GOE-3450; Neurontin) – gabapentinoid (α2δ subunit-containing voltage-gated calcium channel ligand) – migraine [89] Gabapentin enacarbil (1838262; ASP8825; GSK-1838262; Horizant; Regnite; Solzira; XP13512) – gabapentinoid (α2δ subunit-containing voltage-gated calcium channel ligand) – migraine [90] Ganaxolone (CCD-1042; Ztalmy) – GABAA receptor positive allosteric modulator and neurosteroid – migraine [91] HTL-0022562 (BHV-3100; HTL-22562) – calcitonin gene-related peptide receptor (CGRPR) antagonist – migraine [92] IS-159 – serotonin 5-HT1B and 5-HT1D receptor agonist – migraine [93] Lacosamide (ADD-234037; Erlosamide; Harkoseride; SPM-927; SPM-929; Vimpat; Vimpato) – various actions – migraine [94] Lanepitant (LY-303870) – neurokinin NK1 receptor antagonist – migraine [95] Lidocaine transdermal patch (ADL-87223; LidoPAIN) – sodium channel blocker – headache [96] Lornoxicam (Bosporon; Chlortenoxicam; HN-10000; RO-139297; Safem; TS-110; Xefo) – COX inhibitor/NSAID – migraine [97] LY-2300559 – metabotropic glutamate receptor 2 (mGluR2) positive allosteric modulator and cysteinyl leukotriene receptor 1 (CysLTR1) antagonist – migraine [98] LY-334370 – serotonin 5-HT1F receptor agonist and triptan – migraine [99] MEDI-0618 – monoclonal antibody against protease-activated receptor 2 (PAR2) – migraine [100] Olcegepant (BIBN-4096; BIBN-4096BS) – calcitonin gene-related peptide receptor (CGRPR) antagonist – migraine [101] Oxytocin (TI-001; TI-114; TNX-1900; TNX-2900) – oxytocin receptor agonist – migraine [102] Perampanel (E-2007; ER-155055-90; Fycompa) – AMPA receptor antagonist – migraine [103] PF-5180999 (PF-05180999) – phosphodiesterase PDE2 inhibitor – migraine [104] PNU-142633 (PNU-142633F) – serotonin 5-HT1D receptor agonist – cluster headache, headache, migraine [105] Prochlorperazine inhalation (AZ-001) – typical antipsychotic (non-selective monoamine receptor modulator) – migraine [106] Propisergide (ergalgin) – serotonin receptor modulator and ergoline – migraine Propofol phosphate (Neuprox; propofol prodrug) – GABAA receptor positive allosteric modulator (propofol prodrug) – migraine [107] Research programme: migraine therapy - Orexo (OX-40; OX641) – undefined mechanism of action – migraine [108] Selurampanel (BGG-492; BGG-492A) – ionotropic glutamate AMPA and kainate receptor antagonist – migraine [109] Sergolexole (LY-281067) – serotonin 5-HT2 receptor antagonist and ergoline – migraine [110] Telcagepant (MK-0974) – calcitonin gene-related peptide receptor (CGRPR) antagonist – migraine [111] Tezampanel (LY-293558; NGX-424; PRN-001-01) – ionotropic glutamate AMPA and kainate receptor antagonist – migraine [112] Tizanidine (AN-021A; AN-021; DS-103282; Sirdalud; Ternelin; Zanaflex) – α2-adrenergic receptor agonist – migraine [113] Tonabersat (SB-220453; USL-260; Xiflam) – connexin 43 (GJA1) inhibitor – migraine [114] Zolmitriptan inhalation (CVT-427) – serotonin 5-HT1B and 5-HT1D receptor agonist and triptan – migraine [115] Zonisamide (AD-810; CI-912; Excegran; Kinaplase; PD-110843; Tremode; Trerief; Zonegran) – calcium channel blocker, sodium channel blocker, and other actions – migraine [116]
Turin is the Italian city where film chromatography was first established. As such, it forms the birthplace of Italian cinema. Because of its historic, geographical and cultural proximity to France, Italian filmmakers were naturally influenced by French cinema and the Lumière brothers. The first Italian cinema screening occurred in Turin in March 1896. In November 1896, Italian filmmakers performed the first cinema screening of a film before a fee-paying audience. By the start of the 20th century (especially after 1907), a number of the first Italian films were aired in Turin. Examples include Giovanni Pastrone Cabiria, in 1914, one of the first blockbusters in history. The Turin-based company Ambrosio Film, established in 1906 by Arturo Ambrosio, was one of the leading forces in Italian cinema and boosted the importance of the city as a filmmaking destination. The company, noted in particular for its historical epics, produced a large number of films until it was dissolved in 1924. During the 1920s and 30s, Turin hosted a number of film productions and major film studios (film houses), such as the Itala film, Aquila and Fert Studios. Today their heritage is in the modern Lumiq Studios and Virtual Reality Multi Media Spa. Turin's prominence in Italian film continued until 1937, the year Cinecittà was inaugurated in Rome. After World War II, the cinematic scene in Turin continued to thrive. 1956 saw the opening of the National Museum of Cinema, first housed in the Palazzo Chiablese and then, from 2000, in the imposing headquarters of the Mole Antonelliana.
The browning reactions that occur when meat is roasted or seared are complex and occur mostly by Maillard browning with contributions from other chemical reactions, including the breakdown of the tetrapyrrole rings of the muscle protein myoglobin. Maillard reactions also occur in dried fruit and when champagne ages in the bottle. Caramelization is an entirely different process from Maillard browning, though the results of the two processes are sometimes similar to the naked eye (and taste buds). Caramelization may sometimes cause browning in the same foods in which the Maillard reaction occurs, but the two processes are distinct. They are both promoted by heating, but the Maillard reaction involves amino acids, whereas caramelization is the pyrolysis of certain sugars. In the production of animal feed, the Maillard reaction can reduce feed quality by reducing the digestibility of amino acids. In making silage, excess heat causes the Maillard reaction to occur, which reduces the amount of energy and protein available to the animals that feed on it.
Two Boer forces fought in this area, under Botha in the south east and under Ben Viljoen in the north east around Lydenburg. Botha's forces were particularly active, raiding railways and British supply convoys, and mounting a renewed invasion of Natal in September 1901. After defeating British mounted infantry in the Battle of Blood River Poort near Dundee, Botha was forced to withdraw by heavy rain that made movement difficult and crippled his horses. Back on the Transvaal territory around his home district of Vryheid, Botha attacked a British raiding column at Bakenlaagte, using an effective mounted charge. One of the most active British units was effectively destroyed. This made Botha's forces the target of increasingly large scorched earth drives by British forces, in which the British made particular use of native scouts and informers. Eventually, Botha had to abandon the high veld and retreat to a narrow enclave bordering Swaziland. To the north, Ben Viljoen grew steadily less active. His forces mounted comparatively few attacks and as a result, the Boer enclave around Lydenburg was largely unmolested. Viljoen was eventually captured.
Sources: en.wikipedia.org
In the 1930s-1950s, the first protein structures were solved by protein crystallography. These early structures suggested that a fixed three-dimensional structure might be generally required to mediate biological functions of proteins. These publications solidified the central dogma of molecular biology in that the amino acid sequence of a protein determines its structure which, in turn, determines its function. In 1950, Fred Karush at the Neurological Institute of New York described the "configurational adaptability" found in serum albumins contradicting this assumption. Karush was convinced that proteins have more than one configuration at the same energy level and can choose one when binding to other substrates. In the 1960s, Levinthal's paradox suggested that the systematic conformational search of a long polypeptide is unlikely to yield a single folded protein structure on biologically relevant timescales (i.e. microseconds to minutes). Curiously, for many (small) proteins or protein domains, relatively rapid and efficient refolding can be observed in vitro. As stated in Anfinsen's Dogma from 1973, the fixed 3D structure of these proteins is uniquely encoded in its primary structure (the amino acid sequence), is kinetically accessible and stable under a range of (near) physiological conditions, and can therefore be considered as the native state of such "ordered" proteins.
== Research interests == Jorgenson's research group is focused on utilizing analytical separation techniques to solve research problems in complex mixture analysis. The group currently focuses on ultra-high pressure capillary liquid chromatography combined with mass spectrometry (MS). Jorgenson's research group is best known for their breakthrough in the field of separation sciences, the invention of capillary electrophoresis (CE). He began his research at UNC Chapel Hill studying electro-osmotically driven chromatography. The development of CE has aided in the advancement of many fields of science, including DNA sequencing, forensic DNA analysis and analysis of intact proteins. CE technology enabled completion of the sequencing of the human genome far ahead of the expected schedule and far below anticipated cost. Jorgenson's research group is also notable for some of the earliest demonstrations of the analysis of the contents of single cells, comprehensive two-dimensional separations, and the invention of ultra-high pressure liquid chromatography. His publications in separation methods have been extensively cited. Jorgenson retired in 2019 from the University of North Carolina at Chapel Hill. He was awarded the American Chemical Society Award in Separations Science and Technology.
== Research == His main research was to uncover the basic mechanisms for how plants and bacteria use photosynthesis to convert light into chemical energy. In 1971, Feher's laboratory and Roderick Clayton's laboratory independently purified minimal bacterial photosynthetic reaction center preparations from Rhodobacter sphaeroides. Feher's main contributions to science were the development of spectroscopic tools and their applications, in particular, to problems in biochemistry and biophysics. He was the first to develop a form of double-frequency spectroscopy, Electron nuclear double resonance (ENDOR), for which he chose a name reminiscent of the biblical witch of Endor. This was the forerunner of many other double-resonance methods.
== Track listing == "Too Cold To Snow" – 4:42 "Demons In The Scenery" – 3:48 "No Window" – 4:21 "I Spy" – 4:12 "Wreckage" – 3:16 "Demons Die" – 3:30 "Word For Word" – 3:43 "Nerve" – 4:07 "My Baby Only Cares For Me" – 3:30 "Senseless Sentences" – 4:20 "Divine" – 4:09 "Lucky Breaks" – 4:08 "Grace" – 5:02 "Harry: Walkies" - 0:09
The role of caregivers for youth with mental health needs is valuable, and caregivers benefit most when they have sufficient psychoeducation and peer support. Depression is one of the leading causes of illness and disability among adolescents. Suicide is the fourth leading cause of death in 15-19-year-olds. Exposure to childhood trauma can cause mental health disorders and poor academic achievement. Ignoring mental health conditions in adolescents can impact adulthood. 50% of preschool children show a natural reduction in behavioral problems. The remaining experience long-term consequences. It impairs physical and mental health and limits opportunities to live fulfilling lives. A result of depression during adolescence and adulthood may be substance abuse. The average age of onset is between 11 and 14 years for depressive disorders. Only approximately 25% of children with behavioral problems refer to medical services. The majority of children go untreated. A global study of more than 275,000 adolescents aged 12–17 years across 82 countries found that 14% had experienced suicidal thoughts and 9% had anxiety over a 12-month period; adolescents with fewer peer and parental supports and greater exposure to peer conflict, victimisation, and loneliness were at higher risk, and 36 of the 82 countries studied had no specific national mental health policy.
Sources: en.wikipedia.org
TB-500 is a trade-style label for a synthetic peptide connected to thymosin beta-4. It is sold mainly through research-chemical channels and is not a single chemically defined product across suppliers.
Not necessarily. Some vendors use the name for the full 43-residue protein, while others apply it to a short actin-binding fragment or to a related tetrapeptide. The sequence should be confirmed from documentation rather than assumed from the label.
No thymosin beta-4 fragment holds marketing approval as a medicine in major jurisdictions. Material offered for sale is typically labelled for laboratory research only.
Dry lyophilized powder is usually kept frozen, desiccated, and out of direct light. Sealed vials are not opened until needed, because moisture uptake can degrade short peptides. Longer archival storage is often done at lower temperatures than routine working stock.