The short version of peptide purity fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2025-08-21 and is reviewed periodically as new material appears.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, frequently abbreviated as TKPRPGP. It was designed as a structural analogue of tuftsin, a naturally occurring tetrapeptide released by enzymatic cleavage of the immunoglobulin heavy chain. The two additional proline residues at the C-terminal end extend the parent chain and change how the molecule behaves in solution. The free peptide has a calculated molecular mass of approximately 751.9 g/mol and is generally supplied as a lyophilised white to off-white powder.
Development work on the compound began in the 1980s and 1990s at the Institute of Molecular Genetics in Moscow, within the same research programme that produced the peptide Semax. Early investigators sought a tuftsin derivative with improved resistance to enzymatic breakdown and with activity in the central nervous system after peripheral administration. Most of the primary literature from this period was published in Russian, a factor that still shapes how easily the findings can be checked by outside groups.
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 |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Tuftsin analogue |
| Sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Single-letter form: TKPRPGP |
| Molecular formula | C33H57N11O9 | Calculated for the free peptide |
| Molecular weight | About 751.9 g/mol | Derived from the sequence |
| Appearance | White to off-white powder | Typical lyophilised form |
Proposed mechanisms center on modulation of the GABA system, but no single molecular target has been confirmed. Rodent studies report changes in GABA-A receptor expression and in the turnover of serotonin, dopamine, and norepinephrine in several brain regions. Increases in brain-derived neurotrophic factor and its receptor have also been described after repeated administration. These findings come largely from animal models, and the degree to which they describe human neurochemistry remains an open question. The mechanism is best characterized as multi-system and not fully resolved.
Pharmacokinetic data are limited. Like most short peptides, Selank is vulnerable to plasma and tissue peptidases, and its measured half-life in circulation is short, on a minutes scale. The Pro-Gly-Pro tail slows this degradation but does not eliminate it. Intranasal administration is the route described in most reports, with absorption through the nasal mucosa and a hypothesized path into the central nervous system that avoids the blood-brain barrier. Direct measurements of human brain exposure are unavailable, so distribution claims rest on inference from animal work.
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.
I argue that science is beginning to catch up with Jung who was a pioneer whose insights contribute a great deal to our emerging understanding of human consciousness." In this analysis, Jung's paintings of his visions in The Red Book were compared to the paintings of Ayahuasca visions by the Peruvian shaman Pablo Amaringo. Commenting on research that was being undertaken during the 1950s, Jung wrote the following in a letter to Betty Eisner, a psychologist who was involved in LSD research at the University of California: "Experiments along the line of mescaline and related drugs are certainly most interesting since such drugs lay bare a level of the unconscious that is otherwise accessible only under peculiar psychic conditions. It is a fact that you get certain perceptions and experiences of things appearing either in mystical states or in the analysis of unconscious phenomena." An account of Jung and psychedelics, as well as the importance of Jungian psychology to psychedelic-assisted therapies, is outlined in Scott Hill's 2013 book Confrontation with the Unconscious: Jungian Depth Psychology and Psychedelic Experience. A 2021 article discusses Jung's attitude towards psychedelics, as well as the applicability of his ideas to current research. As the author writes, Jung's "...legitimate reservations about the clinical use of psychedelics are no longer relevant as the field has progressed significantly, devising robust clinical and experimental protocols for psychedelic-assisted therapies.
The Port of Dover is a cross-channel ferry, cruise terminal, maritime cargo and marina facility situated in Dover, Kent, south-east England. It is the nearest English port to France, at just 34 kilometres (21 mi) away, and is one of the world's busiest maritime passenger ports, with 11.7 million passengers, 2.6 million lorries, 2.2 million cars and motorcycles and 80,000 coaches passing through it in 2017, and with an annual turnover of £58.5 million a year. This compares with the nearby Channel Tunnel, the only fixed link between the island of Great Britain and the European mainland, which now handles an estimated 20 million passengers and 1.6 million trucks per year. The modern port facility features a large artificial harbour constructed behind stone piers and a defensive concrete breakwater. The port is divided into two main sections: the Eastern Docks serve as the main cross-channel ferry terminal, while the Western Docks contain a cruise ship terminal and a yacht marina along with cargo facilities. The Port of Dover has a long history and possesses several listed buildings and structures. The port is owned and operated by the Dover Harbour Board, a statutory corporation formed by royal charter in 1606 by King James I. Most of the board members of the Dover Harbour Board are appointees of the Department for Transport. The port has its own private police force, the Port of Dover Police. The current port traffic volumes and urban population categorise Dover as a Large-Port Town.
Chewing gum – Native Americans in New England introduced the settlers to chewing gum made from the spruce tree. The Mayans, on the other hand, were the first people to use latex gum; better known to them as chicle.
Sources: en.wikipedia.org
Apomorphine, sold under the brand name Apokyn among others, is a type of aporphine that functions as a non-selective dopamine agonist which activates both D2-like and, to a much lesser extent, D1-like receptors. It also acts as an antagonist of 5-HT2 and α-adrenergic receptors with high affinity. The compound is an alkaloid belonging to Nymphaea caerulea (blue lotus), but is also historically known as a morphine decomposition product made by boiling morphine with concentrated acid, hence the -morphine suffix. Contrary to its name, apomorphine does not actually contain morphine or its skeleton, nor does it bind to opioid receptors. The apo- prefix relates to it being a morphine derivative ("[comes] from morphine"). Historically, apomorphine has been tried for a variety of uses, including as a way to relieve anxiety and craving in alcoholics, an emetic (to induce vomiting), for treating stereotypies (repeated behaviour) in farmyard animals, and more recently in treating erectile dysfunction. Currently, apomorphine is used in the treatment of Parkinson's disease. It is a potent emetic and should not be administered without an antiemetic such as domperidone. The emetic properties of apomorphine are exploited in veterinary medicine to induce therapeutic emesis in canines that have recently ingested toxic or foreign substances. Apomorphine was also used as a private treatment of heroin addiction, a purpose for which it was championed by the author William S. Burroughs.
On 12 September 2024, Paetongtarn Shinawatra and the Cabinet presented their policy statement to Parliament, outlining ten priority policies for immediate implementation. These included comprehensive debt restructuring, measures to support Thai entrepreneurs, reductions in energy and utility costs, and efforts to integrate the informal and underground economies into the tax system. Additional priorities included economic stimulus through digital wallets, modernization of the agricultural sector, tourism promotion, anti-narcotics initiatives, crime prevention, and enhancements to social welfare, particularly for vulnerable groups, stateless individuals, and ethnic minorities. Following the policy announcement, on 13 September 2024, Paetongtarn and relevant Cabinet members visited Mae Sai district, Chiang Rai, to assess the flood situation in northern Thailand.
Carbamazepine, sold under the brand name Tegretol among others, is an anticonvulsant medication used in the treatment of epilepsy and neuropathic pain. It is used as an adjunctive treatment in schizophrenia along with other medications and as a second-line agent in bipolar disorder. Carbamazepine appears to work as well as phenytoin and valproate for focal and generalized seizures. It is not effective for absence or myoclonic seizures. Carbamazepine was discovered in 1953 by Swiss chemist Walter Schindler. It was first marketed in 1962. It is available as a generic medication. It is on the World Health Organization's List of Essential Medicines. In 2023, it was the 185th most commonly prescribed medication in the United States, with more than 2 million prescriptions. Photoswitchable analogues of carbamazepine have been developed to control its pharmacological activity locally and on demand using light (photopharmacology), with the purpose of reducing the adverse systemic effects of the drug. One of these light-regulated compounds (carbadiazocine, based on a bridged azobenzene or diazocine) has been shown to produce analgesia with noninvasive illumination in vivo in a rat model of neuropathic pain.
Sources: en.wikipedia.org
The sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, commonly written as TKPRPGP. It shares the first four residues with tuftsin and carries three prolines in the chain. The proline-rich tail is the main structural feature that separates it from the parent tetrapeptide.
Selank is a synthetic analogue built on the tuftsin tetrapeptide Thr-Lys-Pro-Arg. Extra proline residues were added to the C-terminus during design work. That modification is intended to make the peptide less vulnerable to rapid enzymatic degradation.
Transliteration from Russian produces variant spellings such as Selanc. Many suppliers avoid the trade-style name entirely and list the peptide sequence. Comparing sequences rather than names is the reliable way to confirm two entries describe the same molecule.
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.