This is a working overview of 合成肽, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-12-21 and is reviewed periodically as new material appears.
Thymosin alpha 1 is a 28-amino-acid peptide first isolated from thymosin fraction 5, a bovine thymic extract. Its sequence begins with an acetylated serine residue and carries a high proportion of acidic residues, so the molecule has a net negative charge near neutral pH. Despite the shared name, it is unrelated in sequence to the thymosin beta family. Synthetic material prepared by solid-phase peptide synthesis is identical in sequence to the natural peptide.
Several names appear in the literature for this peptide, including thymalfasin and the abbreviation T-alpha-1. Naming conventions differ among research articles, regulatory documents, and supplier catalogs, which complicates literature searches. Both synthetic and recombinant production routes yield a peptide with the same 28-residue sequence as the thymic isolate. Because the thymosin label also covers unrelated peptides, sources should be compared by sequence rather than by name alone.
The peptide occurs naturally in thymic tissue and has been detected in serum and other biological fluids. Reported concentrations are low, and reliable measurement generally requires immunoassay or mass spectrometry with an enrichment step. It is released from a larger precursor, prothymosin alpha, by proteolytic cleavage, although the enzymes involved are not fully characterized. Whether circulating levels reflect thymic output specifically remains an open question.
胸腺素α1（thymosin alpha 1，Tα1）是一种由28个氨基酸组成的酸性肽，N端被乙酰化，分子量约为3108道尔顿。该肽最早从牛胸腺组织提取物中分离，属于胸腺素组分5的一个成分。其序列在不同哺乳动物中高度保守，提示其具有基本的生物学功能。名称中的“α1”指其在电泳中的迁移位置，并非表示亚型编号。它既存在于胸腺，也存在于脾脏和淋巴结等免疫组织。
20世纪70年代，研究者从胸腺提取物中纯化出多种小肽，Tα1是其中被较早表征的一种。最初的制备依赖组织匀浆和层析步骤，产量低且成分复杂。随着固相肽合成技术成熟，实验室和工业界能够生产与天然序列一致的合成版本。合成肽的纯度可达95%以上，并可通过反相高效液相色谱和质谱进行鉴定。这一转变使研究不再依赖动物胸腺来源。
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C129H215N33O55 | Calculated for the acetylated 28-residue peptide |
| Appearance | White to off-white powder | Lyophilized solid recovered from aqueous buffer |
| Solubility | Freely soluble in water | Typically dissolved in water or buffer before use |
| Typical storage | -20 C or below, desiccated | Protect from light and avoid repeated freeze-thaw cycles |
| Identity testing | Reverse-phase HPLC with mass spectrometry | Retention time and measured mass confirm the sequence |
Storage recommendations center on low temperature, dryness, and protection from repeated freezing and thawing. The intact powder is commonly held at 20 degrees below zero Celsius or colder, while a working solution is divided into single-use aliquots to limit freeze-thaw cycles. Buffered saline or phosphate-buffered saline at neutral pH is frequently used as a diluent. Light sensitivity is not well documented, yet amber vials or foil wrapping are common practice for long-term storage of peptide stocks.
Identity and purity are assessed with a small set of standard peptide methods. Reversed-phase high-performance liquid chromatography separates the main peak from truncated or oxidized species, and its area percentage is the usual purity measure. Mass spectrometry confirms the observed molecular mass against the expected value, while amino acid analysis or peptide mapping checks composition and sequence. Specifications for research-grade material are often stated as 95 percent or higher, though the exact limit depends on the supplier and the intended use.
Thymosin alpha-1 is a synthetic peptide of 28 amino acids whose sequence matches the amino-terminal region of prothymosin alpha. The chain is acetylated at its first residue and contains one disulfide bridge between two cysteine residues, which folds the molecule into a compact loop. Its molecular formula, C129H215N33O55, corresponds to a monoisotopic mass of roughly 3,106 daltons. Material used in laboratories is made by solid-phase synthesis rather than isolated from animal tissue.
Early work on thymic extracts in the 1960s described a heat-stable acidic fraction containing many polypeptides. Separation of that mixture yielded individual components, and thymosin alpha-1 was named as one of them on the basis of assays for T-cell activity. The first preparations came from calf thymus, while subsequent research and clinical material has been chemically synthesized. Nomenclature in older papers is inconsistent, and the same peptide sometimes appears under different designations, which complicates literature searches.
Most published studies on thymosin alpha-1 report changes in immune measurements rather than clinical outcomes, and findings differ across designs and populations. Whether the peptide signals through one defined receptor or through several less specific interactions remains an open question. Its reported circulation half-life of a few hours complicates comparison of dosing schedules across trials. Mechanistic claims are frequently drawn from isolated cell cultures, and how far those results extend to whole organisms is unresolved.
The activity of this peptide is generally described as immunomodulatory rather than directly antimicrobial. Experimental work links it to signaling through certain Toll-like receptors on dendritic cells and to downstream maturation of antigen-presenting cells. Reported effects include expansion of T cell subsets, shifts in cytokine profiles, and increased natural killer cell activity. These observations come largely from cell culture and animal models, and the precise receptor-level events in humans remain incompletely characterized.
The compound has been investigated as an adjunct in chronic viral hepatitis and as a vaccine adjuvant, with results that vary by study design and population. Regulators in some countries have approved a synthetic form for specific indications, while other agencies have not. Whether the peptide produces consistent clinical benefit across diverse patient groups is still an open question, and many trials have been small. Its status is therefore best described as investigational in many contexts and established only narrowly.
The name itself causes confusion, because several unrelated thymic peptides share the thymosin label. Thymosin beta-4, for example, is a different molecule with different functions. Naming conventions in the literature also mix descriptive research terms with assigned nonproprietary names, so a reader should confirm which entity a given paper addresses. Clarifying that point is usually the first step in interpreting any claim about this peptide.
Mitragynine is an indole-based alkaloid and is one of the main psychoactive constituents in the Southeast Asian plant Mitragyna speciosa, commonly known as kratom. It has also been researched for its use to potentially manage symptoms of opioid withdrawal. It is a partial agonist of the μ-opioid receptors; and as such can produce effects similar to those of classic opioids such as morphine. Mitragynine is the most abundant active alkaloid in kratom. In Thai varieties of kratom, mitragynine is the most abundant component (up to 66% of total alkaloids), while 7-hydroxymitragynine (7-OH-MIT) is a minor constituent (up to 2% of total alkaloid content). In Malaysian kratom varieties, mitragynine is present at lower concentration (12% of total alkaloids). Total alkaloid concentration in dried leaves ranges from 0.5–1.5%. Such preparations are orally consumed and typically involve dried kratom leaves which are brewed into tea or ground and placed into capsules.
== Medical uses == In the European Union, metreleptin is indicated in addition to diet to treat lipodystrophy, where people have a loss of fatty tissue under the skin and a build-up of fat elsewhere in the body such as in the liver and muscles. It is used in adults and children above the age of two years with generalized lipodystrophy (Berardinelli–Seip syndrome and Lawrence syndrome); and in adults and children above the age of twelve years with partial lipodystrophy (including Barraquer–Simons syndrome), when standard treatments have failed. In the United States, it is indicated as an adjunct to diet as replacement therapy to treat the complications of leptin deficiency in people with congenital or acquired generalized lipodystrophy.
Extremely high levels of serotonin or activation of certain serotonin receptors can cause a condition known as serotonin syndrome, with toxic and potentially fatal effects. In practice, such toxic levels are essentially impossible to reach through an overdose of a single antidepressant drug, but require a combination of serotonergic agents, such as an SSRI with a MAOI, which may occur in therapeutic doses. However, serotonin syndrome can occur with overdose of certain serotonin receptor agonists, like the NBOMe series of serotonergic psychedelics. The intensity of the symptoms of serotonin syndrome vary over a wide spectrum, and the milder forms are seen even at nontoxic levels. It is estimated that 14% of patients experiencing serotonin syndrome overdose on SSRIs; while the fatality rate is between 2% and 12%.
Sources: en.wikipedia.org
=== Sarcopenia and sarcopenic obesity === In a recently published scoping review led by Kalra, the current evidence linking sarcopenic obesity with cardiovascular disease has been summarised, along with proposed preventive and therapeutic strategies. He has published extensively to enable the diagnosis of sarcopenia and sarcopenic obesity in resource-constrained settings and has led the development of a South Asian consensus document on the subject.
==== Quorum sensing ==== Quorum sensing is a method that depends on detecting cell or molecule densities to trigger specific responses. As cell density increases, signalling molecule concentrations also increase, eventually reaching a threshold that activates a response. This mechanism is useful to lower functioning costs for bacteria, as this allows high-energy responses to only occur when they are triggered as necessary by the signalling molecule. Known signalling molecules observed in algicidal responses include acyl-homoserine lactones (AHLs), quinolones, and diketopiperazines. Taxa such as Pseudomonas sp., Pseudoalteromonas sp., Vibrio sp., and Alteromonas sp. all demonstrate algicidal activity linked to quorum sensing mechanisms.
== I == Sir Christopher Kelk Ingold (1893–1970), English chemist known for introducing concepts such as nucleophile, electrophile, inductive and resonance effects Vladimir Ipatieff (1867–1952), Russian-American chemist who worked in petroleum chemistry and catalysts
In order to specialize in pediatric dentistry, one should receive additional in-depth training from an accredited postgraduate residency program. A pediatric dentistry residency program can be 24 months or more in length. At the end, resident dentists are awarded a certificate in pediatric dentistry with or without a master's degree depending on their program type. Specialized training covers all aspects of oral health care from infancy through adolescence, encompassing behavior management, preventive dentistry, restorative dentistry, sedation dentistry, oral trauma management, interceptive orthodontics, oral medicine and pathology. The majority of residency training is spent on treating pediatric patients in a dental clinic or hospital operating room where the patient is under general anesthesia. Following successful completion of post-graduate training, one becomes Board-eligible for the American Board of Pediatric Dentistry(ABPD) examination. The first part of the Board exam is a written exam. Once passing the written exam, one moves on to the second part, which is an oral examination testing on clinical knowledge. Successful completion of board certification results in Diplomate status in the American Board of Pediatric Dentistry that allows one to practice as a Board-certified pediatric dentist.
Sources: en.wikipedia.org
It is a 28-amino-acid peptide originally purified from a bovine thymic extract and later produced synthetically. It is studied mainly for its effects on immune cell function.
No. The two peptides share part of a name but differ in length, sequence, and net charge. Literature searches that treat them as one compound return misleading results.
Solid-phase peptide synthesis is the usual route, and recombinant expression has also been described. Both approaches produce material matching the natural sequence.
它不是经典的内分泌激素，而是一种免疫调节肽。其作用主要通过局部免疫细胞间的信号传递实现，而非经血液循环作用于远隔器官。