Everything below concerns Pro-Gly-Pro. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2026-03-27. Numbers and descriptions here follow the published literature rather than marketing material.
Quantification in biological matrices relies on liquid chromatography coupled to tandem mass spectrometry with stable-isotope internal standards. Low plasma concentrations and adsorption to container surfaces both complicate measurement. Solid-phase extraction is often needed to reduce matrix interference before injection. Reported limits of quantification differ widely between laboratories, which makes direct comparison of pharmacokinetic results difficult and limits meta-analysis.
Peptide bonds are vulnerable to protease attack, and Selank is no exception. Measured half-life in serum is short, on the order of minutes in several reports, which explains why intranasal administration is the common route described in the literature. Absorption across the nasal mucosa partially bypasses first-pass hepatic metabolism. Quantitative data on human bioavailability remain limited and are difficult to compare across studies.
Once dissolved, the peptide is markedly less stable than the dry powder. Aqueous solutions are subject to backbone hydrolysis and to microbial growth when they are handled without sterile technique. Buffered solutions near neutral pH are common for short-term laboratory work, while acidic conditions are sometimes used to improve solubility. Analytical laboratories generally prepare working solutions fresh rather than storing them, and a residual water film left in a reopened vial can seed degradation even when the container appears dry.
Reversed-phase high-performance liquid chromatography is the standard technique for estimating peptide purity. The result is a peak-area percentage, which describes how much of the detected material elutes as the main peak in one run. Mass spectrometry confirms the molecular mass and can reveal truncated, adducted, or otherwise modified species. Amino acid analysis or tandem mass spectrometry can address sequence fidelity when identity is in doubt. None of these measurements, taken alone, establishes that a sample is fit for any specific purpose.
Lyophilized selank is normally supplied as a dry powder and is considered stable for extended periods when kept cold and dry. Moisture uptake is the main practical threat, because absorbed water promotes both hydrolysis and aggregation in the solid state. Vials are usually warmed to room temperature before opening so that condensation does not form on the powder. Supplier documentation commonly specifies -20 °C for routine storage, with -80 °C used for material intended to be archived for years.
| Property | Value | Notes |
|---|---|---|
| Dry storage temperature | -20 C or below | Sealed, desiccated, protected from light |
| Solution stability | Hours to days at 2-8 C | Depends on buffer and microbial load |
| Preferred pH range | Near neutral to slightly acidic | Alkaline pH accelerates hydrolysis |
| Main degradation routes | Hydrolysis and deamidation | No cysteine or methionine in sequence |
| Identity confirmation | Electrospray mass spectrometry | Observed mass compared with 751.9 Da |
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, written TKPRPGP in one-letter notation. Its structure consists of the immunomodulatory tetrapeptide tuftsin, Thr-Lys-Pro-Arg, extended at the carboxyl terminus by a Pro-Gly-Pro segment. The molecular formula is commonly given as C33H57N11O9, corresponding to a monoisotopic mass near 751.4 Da and an average molecular mass near 751.9 Da. All seven residues are proteinogenic amino acids, and the molecule carries no modified side chains or non-natural linkages.
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.
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.
Most published work on selank originates from a small number of research groups in the Russian Federation. A large share of that record appears in Russian-language journals, which limits access for readers who rely on English-indexed databases. Independent replication by laboratories outside the original research network is sparse in publicly available sources. This concentration of origin and language is a frequently noted feature when the compound is summarized in broader reviews of synthetic peptides.
Reported pharmacological effects center on reduced anxiety-like behavior in animal models and on measures of memory and learning. Proposed contributing mechanisms include modulation of GABAergic signaling, shifts in monoamine turnover, and changes in the activity of enzymes that degrade neuropeptides. Effects on the expression of genes linked to neuroplasticity have also been described. No single molecular target is widely accepted, and whether the behavioral findings arise from one pathway or several remains an open question.
Regulatory treatment varies by jurisdiction. In Russia the compound is a registered prescription product, while in the European Union and the United States it is generally handled as a research chemical without a marketing authorization. Suppliers therefore operate outside pharmaceutical oversight, and buyers rely on supplier documentation for purity and identity claims. Chain of custody and third-party testing are the main verification tools. Analysts note that the absence of a pharmacopoeial monograph for research-grade material limits standardization across vendors.
Purity assessment relies mainly on reverse-phase high-performance liquid chromatography with ultraviolet detection. Because the peptide lacks a strong chromophore, detection often uses backbone absorbance near 214 nm. Identity is confirmed by mass spectrometry, typically electrospray ionization or matrix-assisted laser desorption, comparing the measured mass against the expected value. Amino acid analysis can verify composition after acid hydrolysis. Diastereomer content and residual counterions are reported less often, although both can influence biological assays.
Lyophilized material is generally stable for extended periods when kept dry at or below minus twenty degrees Celsius. Working solutions are less stable, and common practice is to aliquot and freeze them so that repeated freeze-thaw cycles are avoided. Aqueous solutions are sensitive to pH extremes and to microbial growth, so short-term storage at refrigerator temperature is typical. Oxidation and hydrolysis are the principal degradation routes. Reconstitution with sterile water or a mild buffer is standard, and solutions should be protected from light.
The microgravity environment allows control of convection in liquids or gasses, and the elimination of sedimentation. Diffusion becomes the primary means of material mixing, allowing otherwise immiscible materials to be intermixed. The environment allows enhanced growth of larger, higher-quality crystals in solution. The ultraclean vacuum of space allows the creation of very pure materials and objects. The use of vapor deposition can be used to build up materials layer by layer, free from defects. Surface tension causes liquids in microgravity to form perfectly round spheres. This can cause problems when trying to pump liquids through a conduit, but it is very useful when perfect spheres of consistent size are needed for an application. Space can provide readily available extremes of heat and cold. Sunlight can be focused to concentrate enough heat to melt the materials, while objects kept in perpetual shade are exposed to temperatures close to absolute zero. The temperature gradient can be exploited to produce strong, glassy materials.
This stirred up a wave of protest among the Catholic population, and bishops, Catholic organisations and the Centre Party itself united to combat the "red danger". This conflict bridged internal tensions within the party and secured its continual existence despite the turmoil of the revolution. The party however was weakened by its Bavarian wing splitting off and forming the Bavarian People's Party (BVP), which emphasised autonomy of the states and also took a more conservative course. In the 1919 elections for the Weimar National Assembly, the Centre Party gained 91 representatives, being the second largest party after the Social Democratic Party (SPD). The Centre's Constantin Fehrenbach was elected president of the National Assembly. The party actively cooperated with Social Democrats and left-liberal German Democratic Party (DDP) in drawing up the Weimar Constitution, which guaranteed what the Centre had been fighting for since its founding: equality for Catholics and autonomy for Catholic Church throughout Germany. The party was less successful in the school question. Although religious education remained an ordinary subject in most schools, the comprehensive, inter-denominational schools became default.
Quantum dots (QDs) or semiconductor nanocrystals are semiconductor particles a few nanometres in size with optical and electronic properties that differ from those of larger particles via quantum mechanical effects. They are a central topic in nanotechnology and materials science. When a quantum dot is illuminated by UV light, an electron in the quantum dot can be excited to a state of higher energy. In the case of a semiconducting quantum dot, this process corresponds to the transition of an electron from the valence band to the conduction band. The excited electron can drop back into the valence band releasing its energy as light. This light emission (photoluminescence) is illustrated in the figure on the right. The color of that light depends on the energy difference between the discrete energy levels of the quantum dot in the conduction band and the valence band. In other words, a quantum dot can be defined as a structure on a semiconductor which is capable of confining electrons in three dimensions, enabling the ability to define discrete energy levels. The quantum dots are tiny crystals that can behave as individual atoms, and their properties can be manipulated. Nanoscale materials with semiconductor properties tightly confine either electrons or electron holes. The confinement is similar to a three-dimensional particle in a box model. The quantum dot absorption and emission features correspond to transitions between discrete quantum mechanically allowed energy levels in the box that are reminiscent of atomic spectra.
ADP + phosphate + peptideout The 3 substrates of this enzyme are ATP, H2O, and peptide, whereas its 3 products are ADP, phosphate, and peptide. This enzyme belongs to the family of hydrolases, specifically those acting on acid anhydrides to catalyse transmembrane movement of substances. The systematic name of this enzyme class is ATP phosphohydrolase (peptide-exporting).
Sources: en.wikipedia.org
== Metabolism and survival == The metabolism of endolithic microorganisms is versatile; genes involved in sulphur metabolism, iron metabolism and carbon fixation have been found in many endolithic communities. Whether they metabolize directly from the surrounding rock, or excrete an acid to dissolve it first is yet undetermined. According to Meslier & DiRuggiero there are genes found in the endolithic community involved in nitrogen fixation. The Ocean Drilling Program found microscopic trails in basalt from the Atlantic, Indian, and Pacific oceans that contain DNA. Photosynthetic endoliths have also been discovered. As water and nutrients are sparse in the endolith's surrounding environment, water limitation is a key factor in the capacity of survival of many endolithic microorganisms. Many of those microorganisms have adaptations to survive in low concentrations of water. Additionally, pigments such as beta carotenes and chlorophyll, especially in cyanobacteria and some algae, help to protect against dangerous radiation and act as a way to obtain energy. Another characteristic is the presence of a very slow reproduction cycle. Early data suggest some only engage in cell division once every hundred years. In August 2013, researchers reported evidence of endoliths in the ocean floor, perhaps millions of years old and reproducing only once every 10,000 years. Most of their energy is spent repairing cell damage caused by cosmic rays or racemization, and very little is available for reproduction or growth.
==== Acetylcholinesterase inhibitors ==== Acetylcholinesterase inhibitors can provide symptomatic benefit and may not fully remove a person's weakness from MG. While they might not fully remove all symptoms of MG, they still may allow a person the ability to perform normal daily activities. Usually, acetylcholinesterase inhibitors are started at a low dose and increased until the desired result is achieved. If taken 30 minutes before a meal, symptoms will be mild during eating, which is helpful for those who have difficulty swallowing due to their illness. Another medication used for MG, atropine, can reduce the muscarinic side effects of acetylcholinesterase inhibitors. Pyridostigmine is a relatively long-acting drug (when compared to other cholinergic agonists), with a half-life around four hours with relatively few side effects. Generally, it is discontinued in those who are being mechanically ventilated, as it is known to increase the amount of salivary secretions. A few high-quality studies have directly compared cholinesterase inhibitors with other treatments (or placebo); their practical benefit may be so significant that conducting studies in which they would be withheld from some people would be difficult.
European Union law is a system of supranational laws operating within the 27 member states of the European Union (EU). Originally referred to as Community law, it has grown over time since the 1952 founding of the European Coal and Steel Community, to promote peace, social justice, a social market economy with full employment, and environmental protection. The Treaties of the European Union agreed to by member states form its constitutional structure. EU law is interpreted by, and EU case law is created by, the judicial branch, known collectively as the Court of Justice of the European Union. Legal Acts of the EU are created by a variety of EU legislative procedures involving the popularly elected European Parliament, the Council of the European Union (which represents member governments), the European Commission (a cabinet which is elected jointly by the Council and Parliament) and sometimes the European Council (composed of heads of state). Only the Commission has the right to propose legislation. Legal acts include regulations, which are automatically enforceable in all member states; directives, which typically become effective by transposition into national law; decisions on specific economic matters such as mergers or prices which are binding on the parties concerned, and non-binding recommendations and opinions. Treaties, regulations, and decisions have direct effect – they become binding without further action, and can be relied upon in lawsuits. EU laws, especially Directives, also have an indirect effect, constraining judicial interpretation of national laws.
Sources: en.wikipedia.org
==== El Salvador ==== "Triple saldo" is a Salvadorean cuisine bull penis and testicles soup. The soup is simmered for eight hours, with crema and eggs of free-range chickens added at the end. Triple saldo is eaten as an aphrodisiac. Bull penis and testicle tacos (tacos de viril) are becoming popular in Ahuachapán.
Philosophy of technology is a branch of philosophy that studies the "practice of designing and creating artifacts", and the "nature of the things so created". It emerged as a discipline over the past two centuries, and has grown "considerably" since the 1970s. The humanities philosophy of technology is concerned with the "meaning of technology for, and its impact on, society and culture". Initially, technology was seen as an extension of the human organism that replicated or amplified bodily and mental faculties. Marx framed it as a tool used by capitalists to oppress the proletariat, but believed that technology would be a fundamentally liberating force once it was "freed from societal deformations". Second-wave philosophers like Ortega later shifted their focus from economics and politics to "daily life and living in a techno-material culture", arguing that technology could oppress "even the members of the bourgeoisie who were its ostensible masters and possessors". Third-stage philosophers like Don Ihde and Albert Borgmann represent a turn toward de-generalization and empiricism, and considered how humans can learn to live with technology. Early scholarship on technology was split between two arguments: technological determinism and social construction. Technological determinism is the idea that technologies cause unavoidable social changes. It usually encompasses a related argument, technological autonomy, which asserts that technological progress follows a natural progression and cannot be prevented.
Canada is a parliamentary democracy and a constitutional monarchy in the Westminster tradition. The country's head of government is the prime minister, who holds office by virtue of their ability to command the confidence of the elected House of Commons and is appointed by the governor general, representing the monarch of Canada, the ceremonial head of state. The country is a Commonwealth realm and is officially bilingual (English and French) in the federal jurisdiction. It is very highly ranked in international measurements of government transparency, quality of life, economic competitiveness, innovation, education and human rights. It is one of the world's most ethnically diverse and multicultural nations, the product of large-scale immigration. Canada's long and complex relationship with the United States has had a significant impact on its history, economy, and culture. A developed country, Canada's advanced economy has a high nominal per capita GDP globally and ranks among the largest in the world by nominal GDP, relying chiefly upon its abundant natural resources and well-developed international trade networks. Canada is recognized as a middle power; its support for multilateralism and internationalism has been closely related to its foreign policies of peacekeeping and aid for developing countries. Canada promotes its domestically shared values through participation in multiple international organizations and forums.
Sources: en.wikipedia.org
Dry powder is best kept sealed, protected from light, and held at minus 20 degrees Celsius or below. Desiccant packaging helps limit moisture uptake because the material is hygroscopic. A sealed vial should be allowed to equilibrate to room temperature before opening to reduce condensation.
Hydrolysis of peptide bonds and deamidation of arginine and proline residues are the main degradation routes. Alkaline pH and higher temperatures accelerate both processes. Buffered, near-neutral solutions stored cold generally degrade more slowly than unbuffered ones.
Reverse-phase chromatography gives the clearest single view of related impurities and truncated sequences. Mass spectrometry then confirms that the main peak carries the expected mass. Neither test detects enantiomeric impurities, which require a separate chiral assay.
Sealed, desiccated storage at -20 °C or colder is the standard recommendation for research-grade material. Vials should reach room temperature before they are opened, which limits condensation. Repeated temperature cycling is discouraged.