Research chemical comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Updated 2026-06-18. Numbers and descriptions here follow the published literature rather than marketing material.
The compound was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences during the 1980s and 1990s. The stated design goal was to retain the immunomodulatory and central nervous system activity attributed to tuftsin while improving resistance to enzymatic breakdown. Adding a proline-rich tail to the short parent peptide was a deliberate strategy, because proline residues restrict the conformations available to many peptidases. The same laboratory produced Semax, an ACTH fragment analog, and both compounds were developed in parallel as short, enzymatically stabilized peptides intended for intranasal use.
Selank is not a naturally occurring peptide and has no known endogenous counterpart in human physiology. Russian-language sources frequently call it TP-7, while English-language sources use the name Selank almost exclusively. Database indexing is uneven, partly because early reports appeared in regional journals that are not widely cataloged. Some summaries describe the material as a tuftsin analog and others as a synthetic heptapeptide; the labels overlap rather than conflict. Citing the primary sequence resolves ambiguity more reliably than the research or trade name alone.
Handling follows standard practice for research peptides. Material is weighed in a low-humidity environment because the powder absorbs atmospheric moisture. Purity is reported as the percentage area of the main peak in a chromatogram, with specifications commonly set at 95 percent or higher; values below that threshold indicate the presence of truncated or modified species. Residual trifluoroacetate from purification is often present and may affect mass balance. Certificates of analysis should state the analytical method, the column and gradient used, and the lot-specific retention time so that results can be compared across suppliers.
Identity and purity of selank are established with reversed-phase high-performance liquid chromatography coupled to mass spectrometry. The peptide elutes from C18 columns with acetonitrile gradients in water containing trifluoroacetic acid or formic acid, and detection is usually performed by ultraviolet absorbance near 214 nm. Electrospray ionization in positive mode gives a doubly protonated ion near m/z 377, consistent with a mass of about 752 Da. Amino acid analysis or tandem mass spectrometry of fragment ions confirms the sequence. Because the molecule has no aromatic residues, it lacks a usable 280 nm chromophore, so low-wavelength detection or mass spectrometry is required.
Peptide bonds in selank are susceptible to hydrolysis under strongly acidic or basic conditions, and the terminal proline residues are vulnerable to exopeptidase activity in biological samples. Lyophilized powder stored dry at -20 °C typically remains stable for extended periods, whereas aqueous solutions degrade faster and may lose measurable purity within days to weeks depending on pH, temperature, and microbial load. Repeated freeze-thaw cycles promote aggregation and adsorption to container surfaces. For analytical work, solutions are usually prepared fresh, kept cold, and used within a single working day.
| Property | Value | Notes |
|---|---|---|
| Peptide sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Seven residues; tuftsin plus a Pro-Gly-Pro tail |
| Molecular formula | C33H57N11O9 | Commonly reported value for the free peptide |
| Monoisotopic mass | Roughly 751.4 Da | Average molecular mass near 751.9 Da |
| Appearance | White to off-white powder | Typically supplied as a lyophilized solid |
| Solubility class | Freely soluble in water | Also dissolves in saline and other polar solvents |
Animal studies have examined behaviour in tests of anxiety, memory retention and stress response, and several report changes in neurotrophic or neurotransmitter-related markers. The human evidence base is much smaller, consisting mainly of short trials conducted in Russia with limited reporting in English-language journals. Sample sizes are modest and outcome measures vary between studies, so the findings are best described as preliminary. Independent replication under modern trial standards has not been widely reported.
Outside its country of origin the compound is generally handled as a research chemical rather than an approved medicine. No regulatory approval from the United States Food and Drug Administration or the European Medicines Agency has been granted for human use. Identity and purity are normally checked by reverse-phase high-performance liquid chromatography, with mass spectrometry used to confirm the molecular mass. Lyophilised material is stored cold and desiccated, and repeated freeze-thaw cycles are avoided.
Solubility behavior is a practical concern for handling. Selank dissolves readily in water and in common aqueous buffers, which simplifies preparation of working solutions. The choice of solvent, ionic strength, and pH can influence aggregation over time, particularly at higher concentrations. Aqueous solutions are typically sterile-filtered before use. Because stability depends on several variables, storage and handling notes should be treated as general guidance rather than fixed rules, and specific values are best confirmed against a certificate of analysis for each batch.
Characterization of Selank in a laboratory setting relies on standard peptide methods. Reverse-phase high-performance liquid chromatography separates the target from related impurities and provides a purity figure, commonly reported as 95 percent or higher. Mass spectrometry, typically electrospray ionization or matrix-assisted laser desorption, confirms the molecular mass and helps detect truncation or modification. Amino acid analysis can verify composition when a sequence-level check is needed. These techniques together establish identity and purity for a given lot.
=== Depression === Characterized by loss of neuroplasticity, depression is a common mood disorder causing persistent negative emotions and changes in lifestyle. Intranasal delivery of relaxin-3 mimetics demonstrated significant anti-depressant activity in behavior paradigms of rat models. Delivering a thermoresponsive hydrogel loaded with berberine intranasally exhibited high bioavailability in hippocampus and anti-depressant activity.
C-4 or Composition C-4 is a common variety of the plastic explosive family known as Composition C, which uses RDX as its explosive agent. C-4 is composed of explosives, plastic binder, plasticizer to make it malleable, and usually a marker or odorizing taggant chemical. C-4 has a texture similar to modelling clay and can be molded into any desired shape. C-4 is relatively insensitive and can be detonated only by the shock wave from a detonator or blasting cap. A similar British plastic explosive, also based on RDX but with a plasticizer different from that used in Composition C-4, is known as PE-4 (Plastic Explosive No. 4).
Another group that works out of the United States is the American Red Cross. The American Red Cross is part of the International Red Cross, and 95% of all workers within the American Red Cross are volunteers. In the case of all crises, whether food related or not, the American Red Cross in engaged in relieving disaster victims. The Red Cross coordinates with local communities to provide essentials such as food, water, and hot meals for those in need during a crisis.
=== Political === When the Allies achieved victory, Mexico was among the victors, despite only actively sending soldiers in the last year of the conflict. Therefore, the country was a founding member of the United Nations Organization, unlike the founding of the League of Nations in 1919, where it was not invited because it had remained neutral during the First World War. In the international arena, Mexico was more present, taking part in the Dumbarton Oaks Conference, the Treaty of San Francisco, the Bretton Woods Conference, and managed to have its initiative approved so that the dictatorship of Francisco Franco in Spain would not be recognized or admitted as a legitimate government before the UN, because it had been formed with the military aid of Nazi Germany and Fascist Italy.
Also Monte Rosa will receive $50m as an upfront payment and additional payments that will depend on the pre-clinical, clinical, commercial stages and sales, as well as multi-level royalty system and may exceed $2 billion. In March 2024, it was announced Roche had sold Genentech's site in Vacaville, California to the Swiss pharmaceutical company, Lonza for $1.2 billion. In November 2024, Roche acquired Poseida Therapeutics for US $1.0 billion. In April 2025, Roche announced it would invest $50 billion in the United States over the next five years, creating more than 12,000 new jobs. In May 2025, Genentech, a Roche subsidiary agreed a partnership worth $2.1 billion with Orionis Biosciences for the development of a small-molecule protein degrader for cancer. In October 2025, Roche announced the completion of its acquisition, for $3.5 billion, of 89bio, a San-Francisco based company focusing on developing therapies for liver and cardio-metabolic disease.
Sources: en.wikipedia.org
In practice, the solid support is used in excess (often tenfold) to be sure that all expected components are formed. The above limitation is completely removed if the solid support is omitted and the synthesis is carried out in solution. In this case, there is no upper limit concerning the number of components of the library. Both the number of components and the quantity of the library can be freely decided based only on practical considerations. An important modification was introduced in the synthesis of DNA encoded combinatorial libraries by Harbury and Halpin. The solid support in their case is replaced by the encoding DNA oligomers. This makes it possible to synthesize libraries containing even trillions of components and screen them using affinity binding methods. A different way of carrying out solution-phase S&P synthesis is applying scavenger resins to remove the byproducts. Scavenger resins are polymers having functional groups that make it possible to react with and bind components of the excess of reagents then filtered them out from the reaction mixture Two examples: a resin containing primary amino groups can remove the excess of acyl chlorides from reaction mixtures while an acyl chloride resin removes amines. A fluorous technology was described by Curran The fluorous synthesis employs functionalized perfluoroalkyl (Rf) groups like 4,4,5,5,6,6,7,7,8,8,9,9,9-Tridecafluorononyl {CF3(CF2)4CF2CH2CH2-} group attached to substrates or reagents. The Rf groups make it possible to remove either the product or the reagents from the reaction mixture.
=== Controversy and conservation issues === The use and trade of elephant ivory have become controversial because they have contributed to seriously declining elephant populations in many countries. It is estimated that consumption in Great Britain alone in 1831 amounted to the deaths of nearly 4,000 elephants. In 1975, the Asian elephant was placed on Appendix I of the Convention on International Trade in Endangered Species (CITES), which prevents international trade between member states of species that are threatened by trade. The African elephant was placed on Appendix I in January 1990. Since then, some southern African countries have had their populations of elephants "downlisted" to Appendix II, allowing the domestic trade of non-ivory items; there have also been two "one off" sales of ivory stockpiles. In June 2015, more than a ton of confiscated ivory was crushed in New York City's Times Square by the Wildlife Conservation Society to send a message that the illegal trade will not be tolerated. The ivory, confiscated in New York and Philadelphia, was sent up a conveyor belt into a rock crusher. The Wildlife Conservation Society has pointed out that the global ivory trade leads to the slaughter of up to 35,000 elephants a year in Africa. In June 2018, Conservative MEPs' Deputy Leader Jacqueline Foster MEP urged the EU to follow the UK's lead and introduce a tougher ivory ban across Europe. China was the biggest market for poached ivory but announced they would phase out the legal domestic manufacture and sale of ivory products in May 2015.
The C-terminal telopeptide (CTX), also known as carboxy-terminal collagen crosslinks, is the C-terminal telopeptide of fibrillar collagens such as collagen type I and type II. It is used as a biomarker in the serum to measure the rate of bone turnover. It can be useful in assisting clinicians to determine a patient's nonsurgical treatment response as well as evaluate a patient's risk of developing complications during healing following surgical intervention. The test used to detect the CTX marker is called the Serum CrossLaps, and it is more specific to bone resorption than any other test currently available.
Naturally occurring platinum (78Pt) consists of five stable isotopes (192Pt, 194Pt, 195Pt, 196Pt, 198Pt) and one long-lived (half-life 4.83×1011 years) radioisotope (190Pt). There are also 34 known synthetic radioisotopes ranging from 165Pt to 204Pt, and longest-lived of those is 193Pt with a half-life of 50 years. All the others have half-lives under two weeks, most under a day. There are numerous metastable states, of which the most stable are 193mPt and 195mPt with half-lives 4.33 and 4.010 days, decaying to their ground states. Despite the obstacles to measurement with rare isotopes of rare elements, with a very slow decay, the 190Pt/186Os system has been used in isotope geology, though not directly for dating. All isotopes of platinum are either radioactive or observationally stable, meaning that they are predicted to be radioactive but no actual decay has been observed. Platinum-195 is the most abundant isotope, making platinum one of the only three elements to have its most abundant isotope with an odd neutron number (the other two being beryllium and nitrogen); however, it is so only by a small margin, unlike the other two, and is more in the nature of a coincidence.
Sources: en.wikipedia.org
Meanwhile, the regulatory approach favored by Liu would help maintain points of contact between Han and indigenous people, and, according to Wang Zhuo, would make them "more accustomed to Hanization." Liu did not personally reiterate those statements, although this was an argument presented by his faction and criticized by their opponents. In the end, Liu's side prevailed, and wula would not be fully abolished until the establishment of communist rule decades later. Liu did abolish several minor corvée duties, including the provision of firewood, fodder, tea, and miscellaneous services such as sweeping, but these were distinct from the transport corvée. Liu defended the wula system's continued existence in a 1939 conference: "if the people think the corvée is an oppressive policy, then they are wrong." Liu's 1990 biography mentions this as emblematic of the limits of warlord-driven reform compared to the wula's complete abolition under Mao in 1959.
=== Locating trials === Depending on the kind of participants required, sponsors of clinical trials, or contract research organizations working on their behalf, try to find sites with qualified personnel as well as access to people who could participate in the trial. Working with those sites, they may use various recruitment strategies, including patient databases, newspaper and radio advertisements, flyers, posters in places the patients might go (such as doctor's offices), and personal recruitment of trial participants by investigators. Volunteers may search directly to locate trials using a registry run by the U.S. National Institutes of Health and National Library of Medicine to identify studies that are currently recruiting participants, offering simplified navigation and real-time enrollment trial information. Software exists to enable clinicians to find trial options for a possible participant based on genomic data for people with cancer.
=== Side effects === Nicomorphine's side effects are similar to those of other opioids and include itching, nausea and respiratory depression. It is considered by doctors to be one of the better analgesics for the comprehensive mitigation of suffering, as opposed to purely clouding the noxious pain stimulus, in the alleviation of chronic pain conditions.
Progesterone is a progestogen, or an agonist of the nuclear progesterone receptors (PRs), the PR-A, PR-B, and PR-C. In one study, progesterone showed EC50Tooltip half-maximal effective concentration values of 7.7 nM for the human PR-A and 8.0 nM for the human PR-B. In addition to the PRs, progesterone is an agonist of the membrane progesterone receptors (mPRs), including the mPRα, mPRβ, mPRγ, mPRδ, and mPRϵ. It is also a potent antimineralocorticoid (antagonist of the mineralocorticoid receptor (MR)), as well as a very weak glucocorticoid (agonist of the glucocorticoid receptor). Progesterone does not interact significantly with the androgen receptor (AR) or with the estrogen receptor (ER). In addition to its activity as a steroid hormone, progesterone is a neurosteroid. Specifically, it is an antagonist of the sigma σ1 receptor, a negative allosteric modulator of nicotinic acetylcholine receptors, and, via its active metabolites allopregnanolone and pregnanolone, a potent positive allosteric modulator of the GABAA receptor, the major signaling receptor of the inhibitory neurotransmitter γ-aminobutyric acid (GABA).
Many users noticed that Saudi journalist Jamal Khashoggi had a blue checkmark, despite being assassinated in 2018 by the government of Saudi Arabia. Khashoggi's checkmark resulted in an outcry from users of the site. The blue checkmark does not state whether or not it has been gifted or bought. Following the removal of legacy verification, Twitter began verifying the accounts of several celebrities who had been critical of, and did not purchase Twitter Blue, including Stephen King, LeBron James, Hasan Piker, and dril. Musk implied that he was paying for their subscriptions personally. Pope Francis' blue checkmark was removed before being replaced by a gray checkmark; as the head of the Catholic Church, the Pope is the sovereign of Vatican City. A day later, Twitter updated its policy for Twitter Ads requiring all advertisers to be subscribed to Verified Organizations, but businesses spending at least $1000 a month in advertising would automatically receive membership in the Verified Organizations program at no additional cost. On April 22, 2023, Twitter seemingly began issuing blue and gold checkmarks to accounts with at least a million followers, including those belonging to deceased users such as Anthony Bourdain, Chadwick Boseman, and Kobe Bryant. Since the blue checkmark now indicates an active Twitter Blue subscription, several high‑profile users began looking for ways to remove it, usually by briefly changing their display name.
Sources: en.wikipedia.org
The sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, written TKPRPGP in one-letter code. It combines the tetrapeptide tuftsin with a carboxyl-terminal Pro-Gly-Pro extension. This full sequence identifies the molecule more precisely than the research name.
No peptide with this exact sequence has been identified as an endogenous substance. It is a laboratory-designed analog of tuftsin, a naturally occurring immunomodulatory tetrapeptide. The Pro-Gly-Pro extension has no known natural source.
Proline introduces conformational constraints that make a peptide less accessible to common peptidases. This is a standard stabilization strategy in peptide design. The added residues also increase the distance between the active tuftsin portion and typical cleavage sites.
Identity is confirmed by matching the retention time in reversed-phase chromatography against a reference standard and by measuring the molecular mass with mass spectrometry. Tandem mass spectrometry or amino acid analysis can verify the sequence of the seven residues. Because the peptide contains no aromatic amino acids, detection at 280 nm is not useful.