Everything below concerns lyophilized powder. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2026-05-09. Numbers and descriptions here follow the published literature rather than marketing material.
Lyophilised material kept dry at minus 20 degrees Celsius or colder is the most stable form, and suppliers commonly state a shelf life of two years or more under those conditions. Once dissolved, degradation accelerates through hydrolysis and deamidation, particularly at alkaline pH or elevated temperature. Working solutions are usually divided into single-use aliquots to avoid repeated freeze-thaw cycles. The choice of reconstitution solvent affects both stability and the ionic strength of the final preparation.
Reverse-phase high-performance liquid chromatography with ultraviolet detection near 214 nanometres is the standard purity method. Mass spectrometry, typically electrospray ionisation, confirms identity through the expected mass-to-charge pattern. Amino acid analysis can verify composition independently. Chiral purity requires separate techniques such as derivatisation followed by chromatographic separation, and such data are rarely reported for research-grade 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 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.
| 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 |
Regulatory status differs sharply by region. Selank holds a Russian marketing authorization, where it is supplied mainly as nasal drops, while authorities elsewhere have not approved it for medical use. Material sold internationally is therefore usually labeled as a research chemical rather than a medicine. Peer-reviewed publications come predominantly from Russian laboratories, and sample sizes are generally small. Whether the compound produces comparable effects under independent, well-controlled replication remains an open question that the broader literature has not settled.
Selank is a synthetic heptapeptide developed in Russia as a structural analogue of tuftsin, a naturally occurring immunomodulatory tetrapeptide. Its sequence, Thr-Lys-Pro-Arg-Pro-Gly-Pro, keeps the tuftsin core at the N-terminus and appends a Pro-Gly-Pro tail. Researchers at the Institute of Molecular Genetics in Moscow synthesized the compound during the 1990s while searching for peptides with combined anxiolytic and immunomodulatory activity. The added tail was intended to resist enzymatic cleavage and prolong the molecule's presence in circulation.
The compound has a calculated molecular weight near 751.9 daltons and carries a net positive charge at physiological pH because of its arginine residue. It dissolves freely in water and in common aqueous buffers, and typically appears as a white or off-white lyophilized powder. The amide backbone makes the molecule susceptible to peptidases, which limits oral use and favors intranasal or parenteral routes. Nomenclature in the literature varies: the substance is also described by the sequence abbreviation TP-7 and by a Russian trade designation.
Pharmacokinetic data are sparse and largely derived from animal work. After intranasal administration the peptide appears in plasma within minutes, and reported half-lives are short, on the order of minutes to tens of minutes. Degradation proceeds through ordinary proteolytic cleavage into constituent amino acids and smaller fragments. Direct evidence that intact Selank reaches brain tissue in meaningful amounts is limited, and the extent of blood-brain barrier penetration is debated. Some authors argue that fragments, not the parent peptide, carry much of the observed activity.
Published clinical work is concentrated in Russian-language journals and generally involves small samples without independent replication. Systematic reviews in English note the shortage of randomised, placebo-controlled trials and the difficulty of verifying methods from translated reports. Outcome measures vary between studies, which complicates pooling of results. Interest in the compound as a cognitive or anxiolytic agent therefore rests on a thinner evidence base than the volume of citations suggests. Replication in well-powered trials with preregistered endpoints would be needed before firm conclusions about efficacy can be drawn.
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.
Non-road engines (or non-road mobile machinery in the European Union) are internal combustion engines that are used for other purposes than a motor vehicle that is used on a public roadway. The term is commonly used by regulators to classify the engines in order to control their emissions. Non-road engines are used in a wide range of applications which may include machinery and non-road vehicles. In many jurisdictions, the term non-road engine is assumed to refer to the engines that have mobility or portability, which is separated from the term stationary engine. The definition of non-road engine may explicitly exclude certain non-road vehicles such as aircraft, locomotives, and ocean-going marine vessels.
GeneReviews/NCBI/NIH/UW entry on Early-Onset Familial Alzheimer Disease Amyloid+Protein+Precursor at the U.S. National Library of Medicine Medical Subject Headings (MeSH) Entrez Gene: APP amyloid beta (A4) precursor protein (peptidase nexin-II, Alzheimer disease) Human APP genome location and APP gene details page in the UCSC Genome Browser.
=== Biomedical === Nanoscale particles are used in biomedical applications as drug carriers or imaging contrast agents in microscopy. Anisotropic nanoparticles are a good candidate in biomolecular detection. Moreover, nanoparticles for nucleic acid delivery offer an unprecedented opportunity to overcome some drawbacks related to the delivery, owing to their tunability with diverse physico-chemical properties, they can readily be functionalized with any type of biomolecules/moieties for selective targeting. Using nanoparticles in cancer treatment is being extensively researched. Certain characteristics of the tumor microenvironment, including leaky vasculature and poor lymphatic drainage, lead to the accumulation of NPs in the tumor. This is known as the enhanced permeability and retention (EPR) effect, and is a type of passive targeting. Additionally, ligands that bind to certain expressed or over-expressed receptors in the tumor microenvironment can be conjugated to the surface of nanoparticles to actively target the tumor. The accumulation of nanoparticles in the tumor can reduce adverse side effects, which is a major drawback of chemotherapy. In drug delivery, the acidic pH of the tumor microenvironment is often exploited to increase the release of the drug from pH-sensitive materials. Additionally, some NPs can generate heat under laser irradiation (photothermal therapy) or alternating magnetic field (magnetic hyperthermia), which can both kill cancer cells, and release drugs loaded in the nanoparticle.
is not known. The other example, adenosine monophosphate is shown to illustrate the fact that a third species may, in principle, be involved. In fact the concentration of (AMP)H2+3 is negligible at the isoelectric point in this case. If the pI is greater than the pH, the molecule will have a positive charge.
Sources: en.wikipedia.org
=== Multicolour Labelling === Since EosFP can be used in fusion constructs while maintaining functionality of the protein of interest, it is a popular choice for multi-colour labelling studies. In a dual-colour labelling experiment to map the stages of mitosis, HEK293 cells were first stably transfected with tubulin-binding protein cDNA fused to EGFP for visualization of the spindle apparatus. Then, transient transfection of recombination signal-binding protein (RBP) fused to d2EosFP was used to visualize the beginning of mitosis. Photoconversion was completed by fluorescent microscopy and highlighted the separation between two sets of chromosomes during anaphase, telophase and cytokinesis.
== Later career and death == Cremer continued research at the University of Innsbruck and retired in 1971. She remained active in gas chromatography until almost the end of life. In 1990, an international symposium celebrating her work and her ninetieth birthday was held in Innsbruck. She died in 1996. In 2009, the University of Innsbruck established a program in her name which awards highly qualified women scientist in pursuit of a habilitation degree.
=== Surface modification improving cell adhesion === Surface modification can also affect properties that promote cell adhesion. One particular research in 2005 studied the mammalian cell adhesion on the modified surfaces of porous silicon. The research used rat PC12 cells and Human Lens Epithelial (HLE) cells cultured for four hours on the surface modified porous silicon. Cells were then stained with vital dye FDA and observed under fluorescence microscopy. The research concluded that "amino silanisation and coating the pSi surface with collagen enhanced cell attachment and spreading".
== History == The Open Insulin Project was started in 2015 by Anthony Di Franco, himself a type 1 diabetic. He started the project in response to the unreasonably high prices of insulin in the US. The project has been housed in Counter Culture Labs, a community laboratory and makerspace in the Bay Area. Other collaborators include ReaGent, BioCurious and BioFoundry.
== AFL career == Gumbleton's 2007, 2008 and 2009 seasons were all plagued by injury and he played only five AFL games in first three seasons, all of which were in 2007. However, the 2010 season saw much improvement for Gumbleton, having a full pre-season, playing 17 of the first 18 games and being re-signed by Essendon, after showing much improvement. Gumbleton suffered yet another injury in round 18, with broken ribs and a punctured lung, ruling him out for the remainder of the 2010 season. Scott's 2011 season was again plagued by injury and he failed to play any games at AFL level. At the end of 2011 Scott had back surgery to repair a disk. It was hoped the surgery would fix his chronic hamstring issues. In 2012 Scott played his first senior game in nearly two years when he returned against Port Adelaide in round 16, booting three goals. He finished the 2012 season having played six games kicking 11 goals. Despite having long-term offers from rival clubs at the end of 2012 Gumbleton showed his loyalty to Essendon agreeing to a new one-year deal to remain at the club until at least the end of 2013. In October 2013, Gumbleton was recruited by Fremantle, who traded the 55th selection in the 2013 AFL draft to Essendon. After failing to play a senior game in his one season at Fremantle, Gumbleton announced his retirement in September 2014. He returned to Melbourne to play for the Banyule Football Club in the Northern Football League from 2015.
Sources: en.wikipedia.org
=== DCVJ, rigidity sensitive dyes === 4-(dicyanovinyl)julolidine (DCVJ) is a molecular rotor probe with fluorescence that is strongly dependent on the rigidity of its environment. When protein denatures, DCVJ increases in fluorescence. It has been reported to work with 40 mg/ml of antibody.
==== Elicitors ==== Pst DC3000 produces a PsINF1, the INF1 in P. syringae. Hosts respond with autophagy upon detection of this elicitor. Liu et al. 2005 finds this to be the only alternative to mass hypersensitivity leading to mass programmed cell death.
Horseradish peroxidase catalyzes the formation of phenolic radicals in the presence of hydrogen peroxide. Tyrosinase oxidizes phenolic groups into reactive quinones capable of forming crosslinks. Transglutaminase creates covalent bonds between glutamine and lysine residues in polymer chains. These mechanisms enable precise control over crosslinking density, which in turn governs key material properties such as stiffness, degradation rate, and pore size. 1,4 – Butanediol diglycidyl ether (BDDE) Cross-Linked Hyaluronic Acid Fillers
=== Animal rights === Barker was a vegetarian. In 1982, Barker began ending The Price Is Right episodes with the phrase: "This is Bob Barker reminding you to help control the pet population – have your pets spayed or neutered." Though Barker had already been dabbling in animal rights before meeting Burnet, his efforts became more aggressive during his relationship with her. In 1987, Barker requested the removal of fur prizes for the Miss USA pageant and stepped down as host when the producers refused. In 1989, Barker and United Activists for Animal Rights publicly accused several media projects and the American Humane Association of animal mistreatment and condoning animal mistreatment, a tactic which resulted in a $10 million suit against him and the UAAR for libel, slander, and invasion of privacy. The suit was finally settled by the insurer in 1994. Barker founded DJ&T Foundation in 1994, named after his late wife and mother, which has contributed millions of dollars to animal-neutering programs and funded animal rescue and park facilities all over the United States. In 2004, Barker donated $1 million (equivalent to $1.7 million in 2025) to Columbia Law School to support the study of animal rights. In 2009, Barker wrote a letter about three businesses in Cherokee, North Carolina, asking them to close their bear exhibits. He threatened to not attend the 2009 Game Show Awards, where Barker was to receive a lifetime achievement award, because Betty White would be attending.
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.
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.