This is a working overview of proteolysis, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-06-12. Anything still debated is marked as such rather than presented as settled.
Reported activity for Selank centers on anxiolytic and nootropic effects. Russian clinical reports describe use in anxiety and in cognitive or attention-related complaints. Most of this evidence comes from studies conducted by the same research groups that developed the peptide. Independent replication in other countries remains limited, and no major Western regulatory agency has approved the compound for any indication. The gap between local reports and external verification is a recurring point in discussions of the peptide.
Tuftsin, the parent structure, is a naturally occurring immunomodulatory tetrapeptide released from the Fc region of immunoglobulin G by spleen enzymes. Selank extends this four-residue sequence with three additional amino acids. The stated rationale is that the added tail slows enzymatic breakdown and may influence receptor interactions. How the full heptapeptide behaves at the molecular level is not firmly established, and proposed mechanisms often involve indirect modulation of neurotransmitter or immune signaling rather than a single defined target.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Modeled on tuftsin |
| Amino acid sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Seven residues |
| Approximate molecular mass | Around 750 Da | Depends on counter-ion and hydration |
| Common forms | Lyophilized powder | Also described as aqueous solution |
| Primary origin of research | Russian laboratories | Mid-1990s onward |
Identity and purity are usually assessed by reversed-phase high-performance liquid chromatography, with mass spectrometry used to confirm molecular mass and sequence information. Amino acid analysis and peptide mapping may supplement these methods. Certified reference standards are scarce, and many commercial lots are sold as research chemicals without a pharmacopoeial monograph. Regulatory treatment differs by country: Selank is a registered prescription medicine in Russia, while in the European Union and the United States it is not an approved drug and may fall under research-chemical or unapproved-product frameworks.
Selank is a hydrophilic peptide and dissolves readily in water and in aqueous buffers. The lyophilised powder is typically a white to off-white solid. Because short peptides are prone to hydrolysis and oxidation, handling benefits from limiting exposure to heat, moisture and strong light. Working solutions are commonly prepared in sterile water or saline, and repeated freeze-thaw cycles are avoided to reduce aggregation and loss of activity. These practices reflect general laboratory convention rather than published stability specifications.
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.
Proposed mechanisms centre on the GABAergic system. Animal and tissue studies report changes in GABA-A receptor expression and reduced activity of GABA transaminase, the enzyme that degrades GABA. Effects on monoamine turnover, including serotonin and dopamine pathways, are also described, and a separate line of work links the peptide to increased expression of brain-derived neurotrophic factor in hippocampal tissue. Most of these findings come from rodent models and cell preparations. How the individual observations combine into a single coherent mode of action is not settled.
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.
==== Chemistry ==== Amylose and cellulose cannot be used as such due to poor resolution and difficulty in handling. But the carbamate and benzoate derivatives of these polymers, especially amylose and cellulose, demonstrate excellent properties as chiral selectors for chromatographic separation. A large number of polysaccharide-based CSPs are commercially available for chiral separation. These CSPs showed tremendous chiral recognition capability to resolve a wide range of chiral analytes. Many of these CSPs have been marketed by Daicel Chemical Industries, Ltd., and some of the popular ones are listed in the table.
In Switzerland, a maximum radiation exposure of 1 mSv per year and a maximum of 5 mSv per year for the patient's relatives may not be exceeded. After discharge following radioiodine therapy, a maximum dose rate of 5 μSv per hour at a distance of 1 meter is permitted, which corresponds to a residual activity of approximately 150 MBq. In the event of early discharge, the supervisory authority must be notified up to a dose rate of 17.5 μSv/h; above 17.5 μSv/h, permission must be obtained. If the patient is transferred to another ward, the responsible radiation protection officer must ensure that appropriate radiation protection measures are taken there, e.g. that a temporary control area is set up.
== Publication == The first peer reviewed publication describing SEA native peptide ligation was published in Organic Letters by Melnyk, O. et al. (Ollivier, N.; Dheur, J.; Mhidia, R.; Blanpain, A.; Melnyk, O., Bis(2-sulfanylethyl)amino native peptide ligation. Org. Lett. 2010, 12, (22), 5238–41; Publication Date (Web): October 21, 2010. A few weeks later, the same reaction was published in the same journal by Liu, C. F (Hou, W.; Zhang, X.; Li, F.; Liu, C. F., Peptidyl N,N-Bis(2-mercaptoethyl)-amides as Thioester Precursors for Native Chemical Ligation. Org. Lett. 2011, 13, 386–389; Publication Date (Web): December 22, 2010).
== External links == Fibronectin, an Extracellular Adhesion Molecule The Fibronectin Protein Fibronectin at the U.S. National Library of Medicine Medical Subject Headings (MeSH) Fibronectin molecular interactions Overview of all the structural information available in the PDB for UniProt: P02751 (Human Fibronectin) at the PDBe-KB. Overview of all the structural information available in the PDB for UniProt: P11276 (Mouse Fibronectin) at the PDBe-KB.
Andros Darryl Townsend (born 16 July 1991) is an English professional footballer who plays as a right winger for Thai League 1 club PT Prachuap. A graduate of the Tottenham Hotspur academy, Townsend was initially loaned out to several League One and then Championship clubs alongside limited Tottenham first-team appearances, before making his Premier League debut in September 2012. After further limited appearances and then a half-season loan to Premier League club Queens Park Rangers, Townsend established himself as a Tottenham player between 2013 and 2015. He subsequently fell out of favour at Tottenham, and following a short spell at Newcastle United in the 2015–16 season, he transferred to fellow English side Crystal Palace in the summer of 2016. After five years at Palace, he departed for Everton in 2021, though his time at the club was hampered by a long-term injury sustained in 2022. Upon his release from Everton, in July 2023, he joined Luton Town. Townsend earned his first England cap on 11 October 2013, and made 13 appearances in his senior international career, scoring three goals.
Sources: en.wikipedia.org
=== Kidney disease === Scleroderma renal crisis (SRC) is a life-threatening complication of systemic sclerosis that may be the initial manifestation of the disease. Renal vascular injury (due in part to collagen deposition) leads to renal ischemia, which results in activation of the renin-angiotensin-aldosterone system (RAAS). This raises blood pressure and further damages the renal vasculature, causing a vicious cycle of worsening hypertension and renal dysfunction (e.g., elevated creatinine, edema). Hypertensive emergency with end-organ dysfunction (e.g., encephalopathy, retinal hemorrhage) is common. Thrombocytopenia and microangiopathic hemolytic anemia can be seen. Urinalysis is usually normal but may show mild proteinuria, as in this patient; casts are unexpected. The mainstay of therapy for SRC includes ACE inhibitors, which reduce RAAS activity and improve renal function and blood pressure. Short-acting ACE inhibitors (typically captopril) are used because they can be rapidly uptitrated. An elevated serum creatinine level is not a contraindication for ACE inhibitors in this population, and slight elevations in creatinine are common during drug initiation. Scleroderma renal crisis, the occurrence of acute kidney injury, and malignant hypertension (very high blood pressure with evidence of organ damage) in people with scleroderma are effectively treated with drugs from the class of the ACE inhibitors.
=== Gender === Women typically make up some 80% of autoimmune disease patients. Whilst many proposals have been made for the cause of this high weighting, no clear explanation is available. A possible role for hormonal factors has been suggested. For example, some autoimmune diseases tend to flare during pregnancy (possibly as an evolutionary mechanism to increase health protection for the child), when hormone levels are high, and improve after menopause, when hormone levels decrease. Women may also naturally have autoimmune disease trigger events in puberty and pregnancy. Under-reporting by men may also be a factor, as men may interact less with the health system than women.
One non-blinded non-randomized study determined the effectiveness of emoxypine in 205 patients with clinical manifestations of lumbosacral radiculopathy (LSR). Patients were divided into two groups, and further were divided into subgroups depending on the presence of motor disturbances. All patients received a course of conventional medical treatment and physiotherapy; main group additionally received emoxypine. Thereafter, clinical-neurological control of long-term results of treatment in subgroups of patients was performed. The results showed that the use of emoxypine in the combined therapy of patients with LSR led to significant and persistent reduction of severity of pain syndrome and rapid recovery of function of spinal roots and peripheral nerves compared with conventional therapy. However, these studies are primary research, and the effectiveness or purported pharmaceutical efficiency of emoxypine has not yet been validated through a meta analysis or systematic review.
=== Inhibition of methylation === After azanucleosides such as azacitidine have been metabolized to 5-aza-2′-deoxycytidine-triphosphate (decitabine-triphosphate), they can be incorporated into DNA and azacytosine can be substituted for cytosine. Azacytosine-guanine dinucleotides are recognized as substrate by the DNA methyltransferases, which catalyze the methylation reaction by a nucleophilic attack. This results in a covalent bond between the carbon-6 atom of the cytosine ring and the enzyme. The bond is normally resolved by beta-elimination through the carbon-5 atom, but this latter reaction does not occur with azacytosine because its carbon-5 is substituted by nitrogen, leaving the enzyme covalently bound to DNA and blocking its DNA methyltransferase function. In addition, the covalent protein adduction also compromises the functionality of DNA and triggers DNA damage signaling, resulting in the degradation of trapped DNA methyltransferases. As a consequence, methylation marks become lost during DNA replication.
=== Minor characters === Dimitri Chandler: Captain of the Goliath, Chandler mines the outer solar system for ice material which is slowly pushed towards the inner solar system, to make the inner planets habitable through long-term terraforming. Professor Anderson: a medical doctor, Anderson leads the medical team which revived Poole, and works with Indra Wallace both to aid Poole's convalescence, and also to manage his cultural shock at awakening into a strange future world. Dr. Stephen Del Marco: Alive at a future time (2513 AD) which is yet in the novel's distant past, Del Marco is the discoverer of TMA-0 in Africa: an earthbound monolith matching the lunar monolith which had been discovered hundreds of years earlier, in 2001. Dr. Theodore "Ted" Khan: A resident of Ganymede, Dr. Khan is contemptuous of religion, identifying it as a mental disorder.
Sources: en.wikipedia.org
Selank is a synthetic peptide made of seven amino acids. It is modeled on tuftsin, a natural tetrapeptide, with an added three-residue tail. It is not a small-molecule drug.
It originates from research in Russia, associated with the Institute of Molecular Genetics of the Russian Academy of Sciences. The first descriptions date to the mid-1990s. Most published studies come from Russian laboratories.
No, Selank itself does not occur naturally. Its backbone is based on tuftsin, which is produced in the body, but the seven-residue version is a synthetic construct. It is supplied as a manufactured peptide.
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.