peptidase comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Last reviewed on 2026-03-14. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed as a stabilized analogue of tuftsin, a naturally occurring tetrapeptide fragment derived from the immunoglobulin heavy chain. The additional Pro-Gly-Pro segment at the carboxyl terminus is intended to slow enzymatic cleavage. The compound is usually described in the literature as a synthetic peptide with anxiolytic and cognitive-related activity, a label that reflects a research context rather than an approved therapeutic category.
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.
| Property | Value | Notes |
|---|---|---|
| Primary route studied | Intranasal | Also examined parenterally in animal work |
| Reported plasma half-life | Minutes to tens of minutes | Values vary widely between reports |
| Main model systems | Rodent behavioural and cell assays | Human trials are few and small |
| Principal proposed targets | GABA-A receptor, GABA transaminase | Monoamine and neurotrophic pathways also reported |
| Evidence grade | Preliminary | Limited independent replication |
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.
Selank is a synthetic heptapeptide developed in Russia during the 1990s. Researchers at the Institute of Molecular Genetics of the Russian Academy of Sciences designed it as a stabilized analog of tuftsin, a naturally occurring immunomodulatory tetrapeptide. The compound has been studied primarily for its reported anxiolytic and nootropic effects. It remains largely unknown in Western pharmacology and is not approved as a medicine by major regulators such as the FDA or the EMA.
The primary structure of Selank is Thr-Lys-Pro-Arg-Pro-Gly-Pro, corresponding to the molecular formula C33H57N11O9 and a monoisotopic mass of roughly 751.9 daltons. The N-terminal threonine and the arginine residue in the fourth position are shared with tuftsin, which carries the sequence Thr-Lys-Pro-Arg. The three additional residues at the C-terminus, Pro-Gly-Pro, extend the chain and are associated with greater resistance to enzymatic degradation. This extension also separates Selank from the shorter parent peptide.
Naming conventions place Selank in the same research family as Semax, another Russian-developed peptide investigated for cognitive effects. The two compounds share a lineage but differ in sequence and in the biological systems proposed as their targets. Semax descends from ACTH fragments, whereas Selank descends from tuftsin. Publications sometimes identify Selank by its full peptide sequence or by laboratory codes rather than one uniform trade name. Because replication outside Russia is limited, reports on its properties are best read alongside the study design and the purity of the material tested.
Characterization of Selank in laboratory settings relies on standard peptide analytical techniques. Reverse-phase high-performance liquid chromatography separates the peptide from related impurities and degradation products, while mass spectrometry confirms molecular identity through accurate mass measurement. Amino acid analysis and peptide sequencing verify the primary structure when reference material is unavailable. Because Selank is a short chain, fragmentation-based analysis produces a diagnostic ion pattern that supports confident identification.
Peptide stability depends strongly on temperature, moisture, and pH. Lyophilized Selank is generally most stable when stored cold and dry, with freezer temperatures commonly used for long-term storage. In solution, the compound is susceptible to hydrolysis and to microbial growth if it is not handled aseptically. The C-terminal proline-rich extension appears to slow enzymatic cleavage relative to tuftsin, though quantitative degradation rates vary with the matrix and the conditions tested. Published stability data specific to Selank remain sparse.
Quality assessment of Selank samples typically combines purity determination with identity confirmation and counter-ion analysis. Purity is usually reported as a percentage by chromatographic area, with values above 95 percent often quoted for research-grade material. Water content and residual solvents are checked in lyophilized batches because they affect both stability and accurate mass determination. A reported purity figure does not by itself establish that a sample is the intended sequence, so orthogonal methods are needed to rule out sequence isomers or truncation products.
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.
=== Prosecution in Panama === Noriega was tried in absentia in Panama for crimes committed during his rule. In October 1993 Noriega and two others were convicted of the murder of Spadafora by the court of the Third Judicial District, and sentenced to 20 years in prison. Panama's Supreme Court confirmed the sentence on December 20, 1995. In 1994, Noriega and Heráclides Sucre, an agent of his secret police, were convicted by a jury of the murder of Giroldi, who had led the 1989 coup attempt against Noriega. Though Noriega was tried in absentia, a judge traveled to the U.S. to question him in December 1993. Noriega and Sucre both received a 20-year sentence, the maximum penalty sought by the prosecutor. Finally, Noriega received a third 20-year sentence in 1996 for his role in the death of nine military officers supporting Giroldi; the group had been executed in a hangar at the Albrook air base after the coup attempt, in an incident that came to be known as the massacre of Albrook. Noriega was also prosecuted over the 1968 disappearances of Luis Antonio Quirós and Everett Clayton Kimble Guerra in Chiriquí, and the 1971 death of Heliodoro Portugal. These cases had not reached a conclusion at the time of his death in 2017.
== Signal transduction == Through diverse means, extracellular ligand binding will typically cause or stabilize receptor dimerization. This allows a tyrosine in the cytoplasmic portion of each receptor monomer to be trans-phosphorylated by its partner receptor, propagating a signal through the plasma membrane. The phosphorylation of specific tyrosine residues within the activated receptor creates binding sites for Src homology 2 (SH2) domain- and phosphotyrosine binding (PTB) domain-containing proteins. Specific proteins containing these domains include Src and phospholipase Cγ. Phosphorylation and activation of these two proteins on receptor binding lead to the initiation of signal transduction pathways. Other proteins that interact with the activated receptor act as adaptor proteins and have no intrinsic enzymatic activity of their own. These adaptor proteins link RTK activation to downstream signal transduction pathways, such as the MAP kinase signalling cascade. An example of a vital signal transduction pathway involves the tyrosine kinase receptor, c-met, which is required for the survival and proliferation of migrating myoblasts during myogenesis. A lack of c-met disrupts secondary myogenesis and—as in LBX1—prevents the formation of limb musculature. This local action of FGFs (Fibroblast Growth Factors) with their RTK receptors is classified as paracrine signalling. As RTK receptors phosphorylate multiple tyrosine residues, they can activate multiple signal transduction pathways.
Clinical trials for Tanomastat, an alfa-((phenylthio)methyl)carboxylate, showed similar results. It showed good disease stability and tolerance in Phase I solid tumor trials and good tolerance in advanced cancer in combination with Etoposide. However, its efficacy was not proven to be adequate. Tanomastat showed significant hepatotoxicity in a cancer therapy combined with Cisplatin and Etoposide, although in a treatment with Doxorubicin it showed good tolerance and lowered toxicity with 5-fluorouracil and Leucovorin. Many compounds in the thiol zinc-binding groups have good water solubility and are air stable in plasma and these groups will be continued in MMP inhibitor designing.
Sources: en.wikipedia.org
Kynurenic acid (KYNA or KYN) is a product of the normal metabolism of amino acid L-tryptophan. It has been shown that kynurenic acid possesses neuroactive activity. It acts as an antiexcitotoxic and anticonvulsant, most likely through acting as an antagonist at excitatory amino acid receptors. Because of this activity, it may influence important neurophysiological and neuropathological processes. As a result, kynurenic acid has been considered for use in therapy in certain neurobiological disorders. Conversely, increased levels of kynurenic acid have also been linked to certain pathological conditions. Kynurenic acid was discovered in 1853 by the German chemist Justus von Liebig in dog urine, which it was apparently named after.
=== Expansion of the war effort and mine warfare === The defeat at Omugulugwombashe and subsequent loss of Tobias Hainyeko forced SWALA to reevaluate its tactics. Guerrillas began operating in larger groups to increase their chances of surviving encounters with the security forces, and refocused their efforts on infiltrating the civilian population. Disguised as peasants, SWALA cadres could acquaint themselves with the terrain and observe South African patrols without arousing suspicion. This was also a logistical advantage because they could only take what supplies they could carry while in the field; otherwise, the guerrillas remained dependent on sympathetic civilians for food, water, and other necessities. On 29 July 1967, the SADF received intelligence that a large number of SWALA forces were congregated at Sacatxai, a settlement almost a hundred and thirty kilometres north of the border inside Angola. South African T-6 Harvard warplanes bombed Sacatxai on 1 August. Most of their intended targets were able to escape, and in October 1968 two SWALA units crossed the border into Ovamboland. This incursion was no more productive than the others and by the end of the year 178 insurgents had been either killed or apprehended by the police. Throughout the 1950s and much of the 1960s, a limited military service system by lottery was implemented in South Africa to comply with the needs of national defence. Around mid 1967 the National Party government established universal conscription for all white South African men as the SADF expanded to meet the growing insurgent threat.
==== Constrained phenylethylamine compounds ==== Researchers at Abbott Laboratories identified three novel series of DPP-4 inhibitors using HTS. After more research and optimization ABT-341 was discovered (Figure 8). It is a potent and selective DPP-4 inhibitor with a 2D-structure very similar to sitagliptin. However, the 3D-structure is quite different. ABT-341 also has a trifluorophenyl group that occupies the S1-pocket and the free amino group, but the two carbonyl groups are orientated 180° away from each other. ABT-341 is also believed to interact with the Tyr547, probably because of steric hindrance between the cyclohexenyl ring and the tyrosine side-chain. Omarigliptin is one of such compound which is in Phase-III development by Merck & Co.
ventral) side of the thorax, and the assumption that injecting venom in the prey's abdomen leads to venom dilution due to the mixing of fluids in the circulatory system and the guts; the distance where the venom has to travel to be effective also increases, making it less efficient in disabling the prey. Two other concepts have been suggested to explain the reason for prey orientation - one suggested that venom is an expensive product to produce, hence venom conservation is essential; and the other concept suggested that striking the prey in that specific position (i.e. aligning the prey as the same orientation of the centipede) would allow the centipede to sufficiently restraint the prey until the venom takes effect.
Sources: en.wikipedia.org
Reports describe modulation of GABA signalling, changes in monoamine turnover and effects on neurotrophic factor expression. These observations come mainly from animal and cell studies. A single unifying mechanism has not been demonstrated.
The peptide enters plasma rapidly and is broken down by ordinary proteases into amino acids and shorter fragments. Reported half-lives are short. Whether meaningful amounts of the intact molecule reach the brain is an open question.
Most clinical reports are small, published in Russian and not independently replicated. English-language reviews highlight the absence of large randomised trials. Conclusions about efficacy should be treated as provisional.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, designed as a metabolically stabilized analogue of the endogenous tetrapeptide tuftsin. It has been studied mainly against anxiety-related and cognitive endpoints rather than as an approved medicine in most jurisdictions.