A practical reference on heptapeptide: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2025-11-25. Anything still debated is marked as such rather than presented as settled.
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.
| 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 |
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.
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.
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.
His drawing repertoire culminated in an exhibition titled IndigNation, which opened on October 23, 2018, at the Maccarone Gallery in Los Angeles and featured 108 pen-and-ink drawings from Carrey's Twitter feed from 2016 to 2018. In February 2021, Carrey announced he would discontinue political cartoons. In a 2004 interview with 60 Minutes, Carrey reportedly said, "I'm a Buddhist, I'm a Muslim, I'm a Christian." In June 2017, Carrey delivered a speech at a Homeboy Industries event, where he said, “I want to speak to the fact that I believe that this room is filled with God, and that you are heroes to me and I admire you.” He also said, "You've made the decision to walk through the gate of forgiveness, of grace, just as Christ did on the cross."
== Categories == The two basic categories used to classify fish protein powders are dependent on the levels of protein, fat, mineral and carbohydrate contained in the powder. The minerals are mostly naturally occurring, organic complexes of magnesium, calcium and phosphorus. The spray drying process may utilize other minerals and carbohydrates to improve flow characteristics of the final product thus altering the natural balance. Powders will all have a residual moisture content in the 4-8% range.
intrinsically disordered protein (IDP) A protein (or a region or domain within a protein) that lacks any distinct, fixed three-dimensional structure or organization under physiological conditions, instead changing continuously and randomly between multiple transient conformational states rather than folding into any one stable conformation, especially in the absence of specific macromolecular interaction partners. The majority of eukaryotic proteins contain domains with intrinsic structure alongside unstructured domains. Peptide sequences lacking intrinsic order are generally characterized by high proportions of charged and hydrophilic amino acids and low proportions of hydrophobic amino acids, making them inherently flexible, accessible, and modifiable, which allows the same peptide sequence to have distinct functions across a wide variety of biochemical circumstances. They are frequently enriched in binding motifs and are common targets of post-translational modifications, giving them important roles in cell signaling pathways and as hubs in protein complexes.
Sources: en.wikipedia.org
Raw brown mushrooms are 92% water, 4% carbohydrates, 2% protein and less than 1% fat (table). In a reference amount of 100 grams (3.5 oz), raw brown mushrooms provide 22 calories, and are a rich source (20% or more of the Daily Value, DV) of B vitamins, such as riboflavin, niacin and pantothenic acid, selenium (47% DV) and copper (56% DV) (table). They are a moderate source of phosphorus, zinc and potassium (10–15% DV). They have minimal or no vitamin C or sodium content.
Bacterial culture of H. influenzae is performed on agar plates. The strongest growth is seen on chocolate agar at 37 °C in a CO2-enriched incubator. The ideal CO2 concentration for the culture is ~5%. However adequate growth is often seen on brain-heart infusion agar supplemented with hemin and nicotinamide adenine dinucleotide (NAD) Colonies of H. influenzae appear as convex, smooth, pale, grey, or transparent colonies with a mild odor. H. influenzae will only grow on blood agar if other bacteria are present to release these factors from the red blood cells, forming 'satellite' colonies around these bacteria. For example, H. influenzae will grow in the hemolytic zone of Staphylococcus aureus on blood agar plates; the hemolysis of cells by S. aureus releases NAD which is needed for its growth. H. influenzae will not grow outside the hemolytic zone of S. aureus due to the lack of nutrients in these areas.
Rich reported severe side effects from the injections, including emotional blunting and loss of physical sensation. Following a final recommitment order in December 2018, he died by suicide on January 11, 2019, at age 29. His mother, attorney Elizabeth Rich, founded the nonprofit Andrew's V.O.I.C.E. (Victory Over Involuntary Commitment Excesses) to advocate for mental health law reform. His case was documented in a July 2019 investigative article by Robert Whitaker in Mad in America as part of a broader critique of AOT law evidence and practice. A 2023 expert analysis by physician and researcher Peter C. Gøtzsche published in Mad in America documented the case of a Swedish patient, Tuva Andersson, who was forcibly administered paliperidone palmitate depot injections at a forensic psychiatric facility without a confirmed psychotic diagnosis, over her explicit objection. Documented adverse effects included severe muscle stiffness, loss of motor function, and marked cognitive deterioration, which treating clinicians attributed to her underlying condition rather than the medication. An additional medication for Parkinsonism was added rather than the paliperidone being reduced. Andersson died by suicide in 2019, at age 37. A post-mortem assessment by an independent psychiatrist retained by the regional insurance authority concluded that her care had been deficient, that increasing suicide risk had not been met with corresponding interventions, and that her death was likely caused by failures in her treatment.
==== Illegal marketing of Rapamune settlement (2014) ==== A "whistleblower suit" was filed in 2005 against Wyeth, which was acquired by Pfizer in 2009, alleging that the company illegally marketed sirolimus (Rapamune) for off-label uses, targeted specific doctors and medical facilities to increase sales of Rapamune, tried to get transplant patients to change from their transplant drugs to Rapamune, and specifically targeted African Americans. According to the whistleblowers, Wyeth also provided doctors and hospitals that prescribed the drug with kickbacks such as grants, donations, and other money. In 2013, the company pleaded guilty to criminal mis-branding violations under the Federal Food, Drug, and Cosmetic Act. By August 2014, it had paid $491 million in civil and criminal penalties related to Rapamune.
Sources: en.wikipedia.org
There are additives, such as STP Oil Treatment, and some racing oils such as PurOl, PennGrade 1, and Valvoline VR-1, Kixx Hydraulic Oil which are available in the retail market with the necessary amount of ZDDP for engines using increased valve spring pressures.
== Veterinary use == Apomorphine is used to inducing vomiting in dogs after ingestion of various toxins or foreign bodies. It can be given subcutaneously, intramuscularly, intravenously, or, when a tablet is crushed, in the conjunctiva of the eye. The oral route is ineffective, as apomorphine cannot cross the blood–brain barrier fast enough, and blood levels don't reach a high enough concentration to stimulate the chemoreceptor trigger zone. It can remove around 40–60% of the contents in the stomach. One of the reasons apomorphine is a preferred drug is its reversibility: in cases of prolonged vomiting, the apomorphine can be reversed with dopamine antagonists like the phenothiazines (for example, acepromazine). Giving apomorphine after giving acepromazine, however, will no longer stimulate vomiting, because apomorphine's target receptors are already occupied. Apomorphine does not work in cats, who have too few dopamine receptors.
== Function == The Gβγ complex is an essential element in the GPCR signaling cascade. It has two main states for which it performs different functions. When Gβγ is interacting with Gα it functions as a negative regulator. In the heterotrimer form, the Gβγ dimer increases the affinity of Gα for GDP, which causes the G protein to be in an inactive state. For the Gα subunit to become active, the nucleotide exchange must be induced by the GPCR. Studies have shown that it is the Gβγ dimer that demonstrates specificity for the appropriate receptor and that the Gγ subunit actually enhances the interaction of the Gα subunit with the GPCR. The GPCR is activated by an extracellular ligand and subsequently activates the G protein heterotrimer by causing a conformational change in the Gα subunit. This causes the replacement of GDP with GTP as well as the physical dissociation of the Gα and the Gβγ complex.
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.
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.