Heptapeptide 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 2025-12-30. Where a claim depends on a specific study, the study is described rather than over-claimed.
Lyophilized material is generally stable for extended periods when kept dry at or below minus twenty degrees Celsius. Working solutions are less stable, and common practice is to aliquot and freeze them so that repeated freeze-thaw cycles are avoided. Aqueous solutions are sensitive to pH extremes and to microbial growth, so short-term storage at refrigerator temperature is typical. Oxidation and hydrolysis are the principal degradation routes. Reconstitution with sterile water or a mild buffer is standard, and solutions should be protected from light.
Regulatory treatment varies by jurisdiction. In Russia the compound is a registered prescription product, while in the European Union and the United States it is generally handled as a research chemical without a marketing authorization. Suppliers therefore operate outside pharmaceutical oversight, and buyers rely on supplier documentation for purity and identity claims. Chain of custody and third-party testing are the main verification tools. Analysts note that the absence of a pharmacopoeial monograph for research-grade material limits standardization across vendors.
Purity assessment relies mainly on reverse-phase high-performance liquid chromatography with ultraviolet detection. Because the peptide lacks a strong chromophore, detection often uses backbone absorbance near 214 nm. Identity is confirmed by mass spectrometry, typically electrospray ionization or matrix-assisted laser desorption, comparing the measured mass against the expected value. Amino acid analysis can verify composition after acid hydrolysis. Diastereomer content and residual counterions are reported less often, although both can influence biological assays.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Typical purity report | 95% or higher by HPLC | Area percentage at 214 nm |
| Identity confirmation | Mass spectrometry | Electrospray or MALDI |
| Powder storage | -20 C, desiccated | Protect from light |
| Solution storage | 2-8 C short term | Freeze aliquots for longer |
| Quality document | Certificate of analysis | States method and value |
Clinical evidence comes mainly from small studies conducted in Russia, several of which were open-label or lacked robust blinding. Reported outcomes include lower anxiety scores, changes in attention measures, and effects on asthenic states following illness. Sample sizes are typically in the tens of participants, and independent replication outside the region is scarce. Reviews published in English generally note the limited methodological quality of the underlying trials. Whether the compound produces clinically meaningful effects under rigorous conditions remains unresolved.
Proposed mechanisms center on modulation of the GABA system, but no single molecular target has been confirmed. Rodent studies report changes in GABA-A receptor expression and in the turnover of serotonin, dopamine, and norepinephrine in several brain regions. Increases in brain-derived neurotrophic factor and its receptor have also been described after repeated administration. These findings come largely from animal models, and the degree to which they describe human neurochemistry remains an open question. The mechanism is best characterized as multi-system and not fully resolved.
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.
Identity and purity of selank are established with reversed-phase high-performance liquid chromatography coupled to mass spectrometry. The peptide elutes from C18 columns with acetonitrile gradients in water containing trifluoroacetic acid or formic acid, and detection is usually performed by ultraviolet absorbance near 214 nm. Electrospray ionization in positive mode gives a doubly protonated ion near m/z 377, consistent with a mass of about 752 Da. Amino acid analysis or tandem mass spectrometry of fragment ions confirms the sequence. Because the molecule has no aromatic residues, it lacks a usable 280 nm chromophore, so low-wavelength detection or mass spectrometry is required.
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.
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.
Patients with no history of red cell antibodies may qualify for computer-assisted crossmatch, which does not involve combining patient serum with donor cells. If an antibody is suspected, potential donor units must first be screened for the corresponding antigen by phenotyping them. Antigen negative units are then tested against the patient plasma using an antiglobulin/indirect crossmatch technique at 37 degrees Celsius to enhance reactivity and make the test easier to read. In urgent cases where crossmatching cannot be completed, and the risk of dropping hemoglobin outweighs the risk of transfusing uncrossmatched blood, O-negative blood is used, followed by crossmatch as soon as possible. O-negative is also used for children and women of childbearing age. It is preferable for the laboratory to obtain a pre-transfusion sample in these cases so a type and screen can be performed to determine the actual blood group of the patient and to check for alloantibodies.
biomarker A measurable indicator of some biological state, especially a compound or biomolecule whose presence or absence in a biological system is a reliable sign of a normal or abnormal process, condition, or disease. Things that may serve as biomarkers include direct measurements of the concentration of a particular compound or molecule in a tissue or fluid sample, or any other characteristic physiological, histological, or radiographic signal (e.g. a change in heart rate, or a distinct morphology under a microscope). They are regularly used as predictive or diagnostic tools in clinical medicine and laboratory research.
== Disease causation == Changes in DNA caused by mutation in a coding region of DNA can cause errors in protein sequence that may result in partially or completely non-functional proteins. Each cell, in order to function correctly, depends on thousands of proteins to function in the right places at the right times. When a mutation alters a protein that plays a critical role in the body, a medical condition can result. One study on the comparison of genes between different species of Drosophila suggests that if a mutation does change a protein, the mutation will most likely be harmful, with an estimated 70 per cent of amino acid polymorphisms having damaging effects, and the remainder being either neutral or weakly beneficial. Some mutations alter a gene's DNA base sequence but do not change the protein made by the gene. Studies have shown that only 7% of point mutations in noncoding DNA of yeast are deleterious and 12% in coding DNA are deleterious. The rest of the mutations are either neutral or slightly beneficial.
The Bryant Park Restoration Corporation was founded in 1980 by Dan Biederman, along with Andrew Heiskell, chairman of Time Inc. and the New York Public Library. The BPRC immediately brought significant changes to remake the park into a place that people wanted to visit, and instituted a rigorous program to clean the park, remove graffiti, and repair physical damage. The BPRC also created a private security staff to confront unlawful behavior. In addition, the BPRC started an outdoor concert series in the summers. By 1982, arrests had decreased significantly compared to two years prior. Another agency—the Bryant Park Management Corporation, composed of several nearby businesses—was tasked with maintaining the park, spending $525,000 per year to do so. NYC Parks spent an additional $250,000 a year on maintenance, the same amount as when the city had sole control over the park's management. In 1983, HBO's president, Frank Biondi, gave Heiskell a $100,000 check just before the company moved into new headquarters at 1100 Avenue of the Americas, adjacent to the park. At the time, that was the largest donation toward Bryant Park by a private corporation.
=== Ba–Bee === David Baker (b. 1962). American biochemist and computational biologist at the University of Washington, who studies methods to predict and design the three-dimensional structures of proteins. Nobel Prize in chemistry, 2024. Tania A. Baker (PhD 1988). American biochemist at MIT, who has studied transposons and enzymes that catalyse protein unfolding. Member Natl. Acad. Sci. USA. Clinton Ballou (1923–2021). American biochemist at UC Berkeley, whose research focused on the metabolism of carbohydrates and the structures of microbial cell walls. Member Natl. Acad. Sci. USA. Horace Barker (1907–2000). American biochemist and microbiologist at UC Berkeley. Member Natl. Acad. Sci. USA. David Bartel (PhD 1993). American biochemist at MIT, known for work on microRNA biology. Member Natl. Acad. Sci. USA. Bonnie Bassler (b. 1962). American molecular biologist at Princeton, known for studies of quorum sensing, and the idea that disruption of chemical signalling can be used as an antimicrobial therapy. Member Natl. Acad. Sci. USA. Philip A. Beachy (b. 1958). American biochemist at Stanford, known for studies to understand the molecular mechanisms behind the growth of multicellular embryos, especially the role of the Hedgehog signalling pathway. Member Natl. Acad. Sci. USA. Jon Beckwith (b. 1935). American microbiologist and geneticist at Harvard who made important contributions to the study of bacterial genetics. Member Natl. Acad. Sci. USA.
Sources: en.wikipedia.org
A metric foot, defined as 300 millimetres (approximately 11.8 inches), has been used occasionally in the UK but has never been an official unit. The corresponding metric inch of 25 millimetres (0.984 in) was used for pin spacing in Soviet microchips, which were often cloned from Western designs but scaled down slightly from US customary inches to metric inches. This led to incompatibility issues in the Soviet computer market.
==== Cardiac complications ==== Anorexia nervosa increases the risk of sudden cardiac death, though the precise cause is unknown. Cardiac complications include structural and functional changes to the heart. Some of these cardiovascular changes are mild and are reversible with treatment, while others may be life-threatening. Cardiac complications can include arrhythmias, abnormally slow heart beat, low blood pressure, decreased size of the heart muscle, reduced heart volume, mitral valve prolapse, myocardial fibrosis, and pericardial effusion. Abnormalities in conduction and repolarization of the heart that can result from anorexia nervosa include QT prolongation, increased QT dispersion, conduction delays, and junctional escape rhythms. Electrolyte abnormalities, particularly hypokalemia and hypomagnesemia, can cause anomalies in the electrical activity of the heart, and result in life-threatening arrhythmias. Hypokalemia most commonly results in patients with anorexia when restricting is accompanied by purging (induced vomiting or laxative use). Hypotension (low blood pressure) is common, and symptoms include fatigue and weakness. Orthostatic hypotension, a marked decrease in blood pressure when standing from a supine position, may also occur. Symptoms include lightheadedness upon standing, weakness, and cognitive impairment, and may result in fainting or near-fainting. Orthostasis in anorexia nervosa indicates worsening cardiac function and may indicate a need for hospitalization. Hypotension and orthostasis generally resolve upon recovery to a normal weight.
The new 36th district encompasses parts of Southeast Texas, including the Harris County side of the Clear Lake region of Houston. While largely unchanged from its previous iteration, the new iteration includes Lufkin and the surrounding Piney Woods region as well as Silsbee, Jasper and most of Beaumont, and also extends to almost all of Chambers County (including Mont Belvieu) east of Houston) before extending into southeast Houston (including Hobby Airport and Ellington Field, as well as Glenbrook Valley and the aforementioned Clear Lake City development) along with the southeast Harris County communities of Seabrook, Webster and Harris County's portion of Friendswood, and a small sliver of northern Brazoria County centered on most of Pearland. The incumbent is Republican Brian Babin, who was re-elected with 69.4% of the vote in 2024. Donald Trump won 61.8% of the vote in the new district in 2024, as did Ted Cruz with 59.1% of the vote.
== Function == This gene encodes a transmembrane transporter that likely plays a role in monocarboxylic acid transport. A mutation in this gene has been associated with juvenile cataracts with microcornea and renal glucosuria. [provided by RefSeq, Mar 2010].
Vopratelimab (JTX-4014) by Jounce Therapeutics As of 2020 entered Phase I trial Spartalizumab (PDR001) is a PD-1 inhibitor developed by Novartis to treat both solid tumors and lymphomas, which as of 2018 has entered Phase III trials. Camrelizumab (SHR1210) is an anti-PD-1 monoclonal antibody introduced by Jiangsu HengRui Medicine Co., Ltd. that recently received conditional approval in China for the treatment of relapsed or refractory classical Hodgkin lymphoma. Sintilimab (IBI308), a human anti-PD-1 antibody developed by Innovent Biologics and Eli Lilly for patients with non-small cell lung cancer (NSCLC). INCMGA00012 (MGA012) is a humanized IgG4 monoclonal antibody developed by Incyte and MacroGenics. AMP-224 by AstraZeneca/MedImmune and GlaxoSmithKline AMP-514 (MEDI0680) by AstraZeneca Acrixolimab (YBL-006) by Y-Biologics Sasanlimab by Pfizer
Sources: en.wikipedia.org
Purity is usually reported as an HPLC area percentage, most often measured at 214 nm. Identity is confirmed separately by mass spectrometry. A certificate of analysis should state both the method and the observed value.
Dry powder is kept frozen, desiccated, and shielded from light. Dissolved material is aliquoted and frozen to limit freeze-thaw cycles. Short-term refrigerated storage is common for working solutions.
Russia registers it as a prescription nasal product. Most other markets classify it as a research chemical with no approved medical use. Oversight of purity and labeling is consequently minimal in those markets.
The sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, written TKPRPGP in one-letter code. It combines the tetrapeptide tuftsin with a carboxyl-terminal Pro-Gly-Pro extension. This full sequence identifies the molecule more precisely than the research name.