This is a working overview of proteolysis, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-02-18. Anything still debated is marked as such rather than presented as settled.
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.
Selank is a synthetic heptapeptide developed in Russia. Its sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, a seven-residue chain built around the natural tetrapeptide tuftsin. Researchers at the Institute of Molecular Genetics of the Russian Academy of Sciences first described the compound in the mid-1990s. The design combined the tuftsin core with an added Pro-Gly-Pro tail, a modification intended to extend the molecule's stability in biological fluids. Published work on the peptide has appeared mainly in Russian-language journals.
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.
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.
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.
| 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 |
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.
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.
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.
==== Available forms ==== Adderall is available as immediate-release (IR) tablets and extended-release (XR) capsules. Mydayis is available as an extended-release formulation. Adderall XR is approved to treat attention deficit hyperactivity disorder for up to 12 hours in individuals 6 years and older and uses a double-bead formulation. The capsule can be swallowed like a tablet, or it can be opened and the beads sprinkled over applesauce for comparable absorption. Upon ingestion, half of the beads provide immediate administration of medication, while the other half are enveloped in a coating that must dissolve, delaying absorption of its contents. It is designed to provide a therapeutic effect and plasma concentrations identical to taking two doses of Adderall IR four hours apart. Mydayis uses a longer-lasting triple-bead formulation and is approved to treat attention deficit hyperactivity disorder for up to 16 hours in individuals aged 13 years of age and older. In the United States, the immediate and extended-release formulations of Adderall are available as generic medications. Generic formulations of Mydayis became available in the US in October 2023.
=== Indirect (unconjugated) === The measurement of unconjugated bilirubin (UCB) is underestimated by measurement of indirect bilirubin, as unconjugated bilirubin (without/yet glucuronidation) reacts with diazosulfanilic acid to create azobilirubin which is measured as direct bilirubin.
alkanes (paraffins): aliphatic hydrocarbons without any double or triple bonds, i.e. just C-C, C-H single bonds alkenes (olefins): aliphatic hydrocarbons that contain one or more double bonds, i.e. di-olefins (dienes) or poly-olefins. alkynes (acetylenes): aliphatic hydrocarbons which have one or more triple bonds. The rest of the group is classified according to the functional groups present. Such compounds can be "straight-chain", branched-chain or cyclic. The degree of branching affects characteristics, such as the octane number or cetane number in petroleum chemistry. Both saturated (alicyclic) compounds and unsaturated compounds exist as cyclic derivatives. The most stable rings contain five or six carbon atoms, but large rings (macrocycles) and smaller rings are common. The smallest cycloalkane family is the three-membered cyclopropane ((CH2)3). Saturated cyclic compounds contain single bonds only, whereas aromatic rings have an alternating (or conjugated) double bond. Cycloalkanes do not contain multiple bonds, whereas the cycloalkenes and the cycloalkynes do.
== See also == AH-7921 Bezitramide Cebranopadol Deekonda2016 Diphenpipenol DPI-3290 Etazen GSK1702934A J-113,397 Oliceridine PZM21 R6890 SR-14968 SR-16435 SR-17018 List of fentanyl analogues List of orphine opioids
=== Soluble (sRAGE) === The soluble form of RAGE (sRAGE) only includes the extracellular domain and lacks both the transmembrane and cytoplasmic domains. sRAGE can be generated through two primary mechanisms:
Sources: en.wikipedia.org
Capital punishment is a legal and enforced penalty in Singapore. The country is one of four in the developed world to retain the death penalty, along with the United States, Japan and Taiwan. Particularly, its use against drug trafficking has been a source of contention with non-governmental organisations such as Amnesty International and Human Rights Watch. The government has responded that it has "no doubts" that it is the right policy and that there is "clear evidence" of serious deterrence, and that the law should be looked at upon in the wider context of "saving lives", particularly citizens. In 2004, Amnesty International claimed that some legal provisions of the Singapore system for the death penalty conflict with "the right to be presumed innocent until proven guilty". The government has disputed Amnesty's claims, stating that their "position on abolition of the death penalty is by no means uncontested internationally" and that the report contains "grave errors of facts and misrepresentations". From 1938 to 2023, sexual relations between men were technically illegal under Section 377A of the Penal Code, first introduced during British colonial rule. During the last few decades, this law was mostly unenforced and pressure to repeal it increased as homosexuality became more accepted by Singaporean society. Meanwhile, sexual relations between women had always been legal. In 2022, Prime Minister Lee Hsien Loong announced that Singapore would repeal 377A, effectively decriminalising homosexual behaviour.
== Treatment == Solar purpura does not require treatment and may resolve on its own within weeks or months. The lesions may also be permanent. Many people seek treatment for cosmetic purposes. There have been several studies on possible future treatments. A common treatment involves Retinoic acid and other vitamin A derivatives in an attempt to increase dermal thickness and prevent extravasation of red blood cells. The most common treatment is to avoid UV exposure, apply sunscreen, and wear long-sleeved clothing.
=== Structural relationships === Much reference has been made in the literature (both lay and professional) of the structural kinship of synephrine with ephedrine, or with phenylephrine, often with the implication that the perceived similarities in structure should result in similarities in pharmacological properties. However, from a chemical perspective, synephrine is also related to a very large number of other drugs whose structures are based on the phenethylamine skeleton, and although some properties are common, others are not, making unqualified comparisons and generalizations inappropriate. Thus, replacement of the N-methyl group in synephrine with a hydrogen atom gives octopamine; replacement of the β-hydroxy group in synephrine by a H atom gives N-methyltyramine; replacement of the synephrine phenolic 4-OH group by a –H gives halostachine. If the synephrine phenolic 4-OH group is shifted to the meta-, or 3-position on the benzene ring, the compound known as phenylephrine (or m-synephrine, or "Neo-synephrine") results; if the same group is shifted to the ortho-, or 2-position on the ring, o-synephrine results. Addition of another phenolic –OH group to the 3-position of the benzene ring produces the neurotransmitter epinephrine; addition of a methyl group to the α-position in the side-chain of synephrine gives oxilofrine (methylsynephrine). Four stereoisomers (two pairs of enantiomers) are possible for this substance.
La Union was a secret society that became dedicated to the Annexationist Movement, thinking that it would be better for Cuba to become a fully integrated state of the United States, rather than to remain a Spanish possession.
Sources: en.wikipedia.org
The N-hydroxyphthalimide can be removed by shaking with sodium bicarbonate, but the N-hydroxysuccinimide approach shows greater reactivity and convenience, and is generally preferred. Esters of N-hydroxyphthalimide and activated sulfonic acids such as trifluoromethanesulfonic anhydride or p-toluenesulfonyl chloride are used as so-called photoacids, which split off protons during UV irradiation.
== Side effects == The most frequent side effects, occurring in 20% or more of users, are dry mouth, drowsiness, dizziness, constipation, and weight gain (on average 1.8 kg). Other common side effects are headache problems (amblyopia, blurred vision), tachycardia, increased appetite, tremor, fatigue/asthenia/feeling slowed down, and dyspepsia. A less common side effect of amitriptyline is urinary retention (8.7%). Amitriptyline can increase suicidal thoughts and behavior in people under the age of 24 and the US FDA required a boxed warning to be added to the prescription label. Amitriptyline-associated sexual dysfunction (occurring at a frequency of 6.9%) seems to be mostly confined to male patients with depression and is expressed predominantly as erectile dysfunction and low libido disorder, with lesser frequency of ejaculatory and orgasmic problems. The rate of sexual dysfunction in males treated for indications other than depression and in females is not significantly different from placebo. Liver test abnormalities occur in 10–12% of patients on amitriptyline, but are usually mild, asymptomatic, and transient, with consistently elevated alanine transaminase in 3% of all patients. The increases of the enzymes above the 3-fold threshold of liver toxicity are uncommon, and cases of clinically apparent liver toxicity are rare; nevertheless, amitriptyline is placed in the group of antidepressants with greater risks of hepatic toxicity. Amitriptyline prolongs the QT interval. This prolongation is relatively small at therapeutic doses but becomes severe in overdose.
== Adverse effects == BCG immunization generally causes some pain and scarring at the site of injection during infancy. The mechanism of this side effect is not fully understood, however it can be mitigated by performing the vaccination later in life. Usually wealthier regions have lower scar rate among the population, such as Western Europe, unlike its Eastern counterpart, where the BCG scar is considered widespread. The insertion to the deltoid muscle is typically used because the local complication rate is smallest for that site. In most countries it is the left shoulder, although some, like Brazil, administer the vaccination to the right. Nonetheless, the buttock is an alternative site of administration because it provides better cosmetic outcomes.
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.
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.