Heptapeptide raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2025-11-14. Anything still debated is marked as such rather than presented as settled.
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.
Lyophilized selank is normally supplied as a dry powder and is considered stable for extended periods when kept cold and dry. Moisture uptake is the main practical threat, because absorbed water promotes both hydrolysis and aggregation in the solid state. Vials are usually warmed to room temperature before opening so that condensation does not form on the powder. Supplier documentation commonly specifies -20 °C for routine storage, with -80 °C used for material intended to be archived for years.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Typical purity specification | 95 percent or higher by RP-HPLC | Area percentage of the main peak |
| Identity confirmation | Electrospray ionization mass spectrometry | Observed mass compared with the theoretical value near 751.9 Da |
| Recommended dry storage | -20 °C, desiccated | -80 °C for multi-year archival material |
| Solution handling | Prepare fresh; avoid long storage | Sterile filtration reduces microbial load |
| Common synonyms | TKPRPGP; TP-7 | Sequence code and laboratory designation used interchangeably |
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.
Development work on the compound began in the 1980s and 1990s at the Institute of Molecular Genetics in Moscow, within the same research programme that produced the peptide Semax. Early investigators sought a tuftsin derivative with improved resistance to enzymatic breakdown and with activity in the central nervous system after peripheral administration. Most of the primary literature from this period was published in Russian, a factor that still shapes how easily the findings can be checked by outside groups.
Naming for this compound is not fully standardised in English sources. The spelling Selanc appears in some transliterations, and catalogue entries may instead list the peptide sequence itself as the identifier. Reference material sometimes groups it with other short synthetic peptides studied for behavioural effects, which can create confusion when citations are compared. Distinguishing the exact sequence from related tuftsin analogues is therefore a practical first step when reviewing any dataset or specification sheet.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, frequently abbreviated as TKPRPGP. It was designed as a structural analogue of tuftsin, a naturally occurring tetrapeptide released by enzymatic cleavage of the immunoglobulin heavy chain. The two additional proline residues at the C-terminal end extend the parent chain and change how the molecule behaves in solution. The free peptide has a calculated molecular mass of approximately 751.9 g/mol and is generally supplied as a lyophilised white to off-white powder.
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.
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.
== Role in disease == Mutations may lead to decreased or increased activity of enzymes. This may have different consequences, depending on the normal function of the serine protease. For example, mutations in protein C can lead to protein C deficiency and predisposing to thrombosis. Also, some proteases play a vital role in host cell-virus fusion activation by priming virus's Spike protein to show the protein named "fusion protein" (TMPRSS2 activate SARS-CoV-2 fusion). Exogenous snake venom serine proteases cause a vast array of coagulopathies when injected in a host due to the lack of regulation of their activity.
Sanders steadily polled between 15% and 20% on most national surveys between May and September 2019, according to the RealClearPolitics average. This placed him in a decisive second-place behind Joe Biden until Elizabeth Warren and Kamala Harris caught up in July. From mid-February 2020 to the start of March, Sanders polled in first place in the Democratic primary ahead of Joe Biden and was described by the press as the party's presidential front-runner. According to a RealClearPolitics analysis, Sanders received the third-most mentions on CNN, Fox News, and MSNBC between January and August 2019, trailing only Joe Biden and Kamala Harris. Biden, however, received twice as many mentions as Sanders and Harris. Mentions of Sanders on ABC World News Tonight found him in second place, though also trailing Biden by a large margin. Online mentions "reflect a slightly more balanced picture", with both Sanders and Elizabeth Warren running "neck-and-neck" with Biden.
== Operations == Unichem's Formulations manufacturing facilities are located at Goa, Ghaziabad (Uttar Pradesh) and Baddi (Himachal Pradesh). Active Pharmaceutical Ingredient (API) manufacturing facilities are located at Roha (Maharashtra), Pithampur (Madhya Pradesh) and Kolhapur (Maharashtra). Goa, Ghaziabad, Roha, Pithampur and Kolhapur sites are USFDA approved and all the plants are approved from other major health authorities. The Company's facilities have been approved by various International health authorities such as USFDA, UK MHRA, ANVISA (Brazil), COFEPRIS (Mexico), PMDA (Japan), TGA (Australia), SAPHRA (South Africa) and MFDS(Korea), EDQM (European Directorate for the Quality of Medicines), TPD (Canada).
== Production == In 2009, the worldwide capacity for producing formic acid was 720 thousand tonnes (1.6 billion pounds) per year, roughly equally divided between Europe (350 thousand tonnes or 770 million pounds, mainly in Germany) and Asia (370 thousand tonnes or 820 million pounds, mainly in China) while production was below 1 thousand tonnes or 2.2 million pounds per year in all other continents. It is commercially available in solutions of various concentrations between 85 and 99 w/w %. As of 2009, the largest producers are BASF, Eastman Chemical Company, LC Industrial, and Feicheng Acid Chemicals, with the largest production facilities in Ludwigshafen (200 thousand tonnes or 440 million pounds per year, BASF, Germany), Oulu (105 thousand tonnes or 230 million pounds, Eastman, Finland), Nakhon Pathom (n/a, LC Industrial), and Feicheng (100 thousand tonnes or 220 million pounds, Feicheng, China). 2010 prices ranged from around €650/tonne (equivalent to around $800/tonne) in Western Europe to $1250/tonne in the United States.
Sources: en.wikipedia.org
Nisin is a polycyclic antibacterial peptide produced by the bacterium Lactococcus lactis that is used as a food preservative. It has 34 amino acid residues, including the uncommon amino acids lanthionine (Lan), methyllanthionine (MeLan), didehydroalanine (Dha), and didehydroaminobutyric acid (Dhb). These unusual amino acids are introduced by posttranslational modification of the precursor peptide. In these reactions a ribosomally synthesized 57-mer is converted to the final peptide. The unsaturated amino acids originate from serine and threonine, and the enzyme-catalysed addition of cysteine residues to the didehydro amino acids result in the multiple (5) thioether bridges. Subtilin and epidermin are related to nisin. All are members of a class of molecules known as lantibiotics. A recent study has highlighted that the genetic capacity to produce nisin is more widespread than previously thought with over 100 species predicted to encode the genes to produce the peptide. In the food industry, nisin is obtained from the culturing of L. lactis on natural substrates, such as dextrose, and it is not chemically synthesized. It was originally isolated in the late 1930s, and produced since the 1950s as Nisaplin from naturally occurring sources by Aplin and Barrett in laboratories in Beaminster in Dorset (now owned by International Flavors & Fragrances), and approved as an additive for food use in the US in the late 1960s.
A methadone clinic is a medical facility where medications for opioid use disorder (MOUD) are dispensed. Historically and most commonly, these MOUDs are methadone, although buprenorphine is also increasingly prescribed. Medically assisted drug therapy treatment is indicated in patients who are opioid-dependent or have a history of opioid dependence. Methadone is a schedule II (USA) opioid analgesic, that is also prescribed for pain management. It is a long-acting opioid that can delay the opioid withdrawal symptoms that patients experience from taking short-acting opioids, like heroin, and allow time for withdrawal management. In the United States, by law, patients must receive methadone under the supervision of a physician, and dispensed through the Opioid Treatment Program (OTP) certified by the Substance Abuse and Mental Health Services Administration (SAMHSA) and registered with the Drug Enforcement Administration (DEA). The usual process at the clinic is dispensing methadone daily in liquid form, and ingestion is supervised by the physician. Initially, methadone treatment consists of 30mg to 40mg of methadone. Initial doses are followed by increases in the following days until withdrawal symptoms are suppressed. Many patients with opioid use disorder see effective results in symptom management and compliance on 80mg to 120mg of methadone per day. Although there is no set schedule for the gradual increase of dosage, patients typically experience a 5mg to 10mg increase each day for 5-7 days, until they are maintaining a 60mg per day dosage under physician observation.
Sirolimus, also known as rapamycin and sold under the brand name Rapamune among others, is a macrolide compound that is used to coat coronary stents, prevent organ transplant rejection, treat a rare lung disease called lymphangioleiomyomatosis, and treat perivascular epithelioid cell tumour (PEComa). It has immunosuppressant functions in humans and is especially useful in preventing the rejection of kidney transplants. It is a mammalian target of rapamycin (mTOR) kinase inhibitor that reduces the sensitivity of T cells and B cells to interleukin-2 (IL-2), inhibiting their activity. This compound also has a use in cardiovascular drug-eluting stent technologies to inhibit restenosis.
Sources: en.wikipedia.org
Sealed, desiccated storage at -20 °C or colder is the standard recommendation for research-grade material. Vials should reach room temperature before they are opened, which limits condensation. Repeated temperature cycling is discouraged.
A reported purity value reflects the share of the main peak in one chromatographic run and says nothing about identity. Confirming that the expected sequence is present requires a separate measurement such as mass spectrometry. Purity and identity are distinct questions.
A mass spectrum reports the molecular masses present in a sample and shows whether they match the value expected for selank, near 751.9 Da. It also flags common artifacts such as truncation or adduct formation. It does not establish correct stereochemistry or complete sequence order on its own.
Selank is a synthetic seven-amino-acid peptide modeled on tuftsin, a fragment of the immunoglobulin G heavy chain. It was designed in Russia to combine anxiolytic and immunomodulatory properties in one molecule.