The short version of Enkephalinase fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2025-10-09 and is reviewed periodically as new material appears.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences as a structural analogue of tuftsin, a naturally occurring tetrapeptide fragment of the immunoglobulin heavy chain. The added Pro-Gly-Pro tail was intended to slow enzymatic degradation and extend biological activity. In Russia it is registered as an anxiolytic nasal preparation, while regulators elsewhere have not approved it for clinical use.
Proposed mechanisms centre on modulation of the GABAergic system, with reports of altered expression of genes related to GABA-A receptor subunits and changed monoamine turnover. Some studies describe inhibition of enkephalinase, the enzyme that degrades endogenous enkephalins, which may prolong opioid peptide signalling. Effects on brain-derived neurotrophic factor and on cytokine expression have also been reported. These findings come largely from animal models and small human studies, and the precise primary target remains unresolved.
Published clinical evidence is limited. Most controlled trials were conducted in Russia, enrolled modest numbers of participants, and appeared in Russian-language journals, which restricts independent verification. Reported outcomes include lower anxiety scores, improved attention and memory measures, and changes in fatigue ratings. Reviews written in English note methodological limitations such as small samples and inconsistent endpoints. Whether the compound produces clinically meaningful benefit relative to established anxiolytics is therefore an open question rather than an established finding.
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.
Lyophilized Selank, the dry powder form, is generally stored frozen at minus 20 degrees Celsius or colder for long-term keeping. The solid is hygroscopic and should stay sealed, dry, and protected from light. Once dissolved, the peptide is less stable and is usually held refrigerated at 2 to 8 degrees Celsius for short periods. Repeated freezing and thawing is avoided because it can promote aggregation and loss of activity. Buffers and pH choice also affect how long a solution remains usable.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C33H57N11O9 | Free peptide form |
| Molecular mass | About 751.9 Da | Calculated average mass |
| Amino acid sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Single-letter form TKPRPGP |
| Structural basis | Tuftsin analogue | Extended version of a natural tetrapeptide |
| Development origin | Russian Academy of Sciences | Work carried out from the 1980s onward |
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.
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.
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.
Future Directions Recent studies are becoming more concerned with personalizing stimulation parameters, such as individualized targeting, state-dependent stimulation (e.g. on the basis of EEG markers), and dose, frequency, and electrode/magnetic coil placement optimization. Moreover, the development of integrative treatment methods, including the combination of stimulation with cognitive therapy, psychotherapy or neurofeedback, presents a growing field of research.
A complete cessation of the Jewish migration to Palestine. A total halt to the sale of land to Jews. Cancelation of the British Mandate in Palestine and the Balfour Declaration. Recognition of the right of Arabs to their land and recognition of the independence of Palestine as a sovereign state, like all other Arab states, with a promise to provide minority rights to the Jews according to the rules of democracy. The Arab states and the Arab Higher Committee officially boycotted the United Nations Special Committee on Palestine (UNSCOP) formed in May 1947 to investigate the cause of the conflict in Palestine, and, if possible, devise a solution. Despite the official Arab boycott, several Arab officials and intellectuals privately met UNSCOP members to argue for a unitary Arab-majority state, among them AHC member and former Jerusalem mayor Husayn al-Khalidi. UNSCOP also received written arguments from Arab advocates. The Arab Higher Committee rejected both the majority and minority recommendations within the UNSCOP report. They "concluded from a survey of Palestine history that Zionist claims to that country had no legal or moral basis". The Arab Higher Committee argued that only an Arab State in the whole of Palestine would be consistent with the UN Charter. The Arab Higher Committee as well as the Arab states were actively involved in the deliberations of the Ad Hoc Committee on the Palestinian Question, formed in October 1947, again repeating its previous demands.
The global moisture budget is primarily being influenced by tropical sea surface temperatures from the position of the Intertropical Convergence Zone (ITCZ). The Southern Hemisphere has a unique meteorological feature positioned in the southwestern Pacific Basin called the South Pacific Convergence Zone (SPCZ), which contains a perennial position within the Southern Hemisphere. During ENSO warm periods, the SPCZ reverses orientation extending from the equator down south through Solomon Islands, Vanuatu, Fiji and towards the French Polynesian Islands; and due east towards South America affecting geochemistry of corals in tropical regions. Geochemical analysis of skeletal coral can be linked to sea surface salinity (SSS) and sea surface temperature (SST), from El Nino 3.4 SSTA data, of tropical oceans to seawater δ18O ratio anomalies from corals. ENSO phenomenon can be related to variations in sea surface salinity (SSS) and sea surface temperature (SST) that can help model tropical climate activities.
Sources: en.wikipedia.org
At Adelaide, because of the absence of Professor Johnston, he was appointed Acting Chair of Zoology, as acting head of the department he organised the new department and its teaching. Here he was influenced by Wood Jones, Professor of Anatomy, and the physiologist Professor Brailsford Robertson, one of the pupils of Jacques Loeb. Oscar Tiegs spent three years at Adelaide, during which time he was granted a Bachelor of Science degree in 1922 and obtained his Doctorate of Science degree in 1922 both from the University of Adelaide, at the age of 25, his thesis being on the histology of metamorphosis of a pteromalid wasp (Nasonia), specifically Nasonia brevicornis (now designated Nasonia vitripennis). Oscar Tiegs' doctoral thesis work was to be the basis for much of his later work, in embryological studies, and the study of fine structures in muscle. He found clear evidence that the apparent striation of muscle fibres did not arise from separate disks, but from a helicoidal organisation within the fibre. He also found a similar condition in vertebrate muscles. Later he discovered that former histologists had recorded the same thing, but their observations had received little attention. He contended that helicoidal striation is a general feature of muscles and that muscular conduction takes place along this helicoidal path, even though the evidence for this generality was against him, yet his cinematographic records supported his interpretation for arachnids and other arthropods.
=== Millennium Cybernetics === In 1994, Ayyadurai founded a company called Millennium Cybernetics, which produces email management software originally called Xiva and now called EchoMail. The software analyzes incoming email messages to organizations before either replying automatically or forwarding it to the most relevant department. By 2001, customers included Kmart, American Express, and Calvin Klein, as well as more than thirty U.S. senators to help handle constituent email. EchoMail competed with more established customer relationship management software that had an email component.
== History == Robert Vince and Susan Daluge along with Mei Hua, a visiting scientist from China, developed the medication in the '80s. Abacavir was approved by the US Food and Drug Administration (FDA) in December 1998 and is the fifteenth approved antiretroviral drug in the United States.
=== Forum === A major feature of Planet Half-Life, and all other Planet sites was its public forum. These forums included boards ranging from general discussion to technical help. In August 2007, the forums changed format to comply with GameSpy's ForumPlanet standard (the IGN SnowBoards system), removing some outdated features and adding many new ones, such as a dynamic news box that streams in late-breaking news from not only PHL, but all other planet sites as well. This also changed the registration process for the forum, from a per-planet account basis to a network-wide, global account basis. At this time Planet Half-Life's sister sites Planet Fortress and CS.net were officially unsupported and their forums were to be merged into PHL's, although this process lasted over a year before it was complete.
Sources: en.wikipedia.org
It is a seven-amino-acid peptide, Thr-Lys-Pro-Arg-Pro-Gly-Pro, produced by chemical synthesis rather than extracted from biological tissue. Its design is based on tuftsin, a natural immunomodulatory tetrapeptide. The C-terminal Pro-Gly-Pro segment is a common stabilising motif in short regulatory peptides.
The core four residues correspond to tuftsin, which occurs naturally as part of immunoglobulin G. The full seven-residue sequence, however, is not a known endogenous peptide. It is a laboratory-designed analogue intended to combine tuftsin-like activity with greater resistance to breakdown.
No single receptor has been confirmed as the primary target. Reports describe involvement of the GABAergic system, interference with enkephalin degradation, and shifts in neurotrophic factor expression. Because these observations come from different models and assays, they have not yet been integrated into one accepted mechanism.
Reverse-phase HPLC is the usual method and gives a percentage purity value. Mass spectrometry then confirms the molecular mass. Together they provide a basic identity and purity profile for a lot.