Pro-Gly-Pro 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 2025-08-16. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
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.
| 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 |
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.
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.
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.
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.
{\displaystyle \langle \Psi _{nlm_{l}m_{s}}|\mu |\Psi _{n'l'm_{l}'m_{s}'}\rangle } For example in the E1 transition, unless Δ l = ± 1, Δ ml = 0 or ± 1, Δ ms = 0, and Δ n = any integer, the equation above will yield a value equal to zero and the transition would be known as a “forbidden transition”. For example, this would occur for certain cases like when Δ l = 2. In this case, the transition would not be allowed and therefore would be much weaker than an allowed transition. These specific values for the changes in quantum numbers are known as the selection rules for the allowed transitions and are shown for common transitions in the table below: Cold vapour atomic fluorescence spectroscopy Atomic spectral line Prospects in Analytical Atomic Spectrometry – tendencies in five main branches of atomic spectrometry (absorption, emission, mass, fluorescence and ionization spectrometry) Learning by Simulations – various atomic absorption and emission spectra Atomic Spectroscopy: A Compendium of Basic Ideas, Notation, Data, and Formulas
Thorium (90Th) has seven naturally occurring isotopes but none are stable. One isotope, 232Th, is relatively stable, with a half-life of 1.40×1010 years, considerably longer than the age of the Earth, and even slightly longer than the generally accepted age of the universe. This isotope makes up nearly all natural thorium, so thorium was considered to be mononuclidic. However, in 2013, IUPAC reclassified thorium as binuclidic, due to large amounts of 230Th in deep seawater. Thorium has a characteristic terrestrial isotopic composition and thus a standard atomic weight can be given. Thirty-one radioisotopes have been characterized, with the most stable being 232Th, 230Th with a half-life of 75,400 years, 229Th with a half-life of 7,916 years, and 228Th with a half-life of 1.91 years. All of the remaining radioactive isotopes have half-lives that are less than thirty days and the majority of these have half-lives that are less than ten minutes. One isotope, 229Th, has a nuclear isomer (or metastable state) with a remarkably low excitation energy, recently measured to be 8.355733554021(8) eV It has been proposed to perform laser spectroscopy of the 229Th nucleus and use the low-energy transition for the development of a nuclear clock of extremely high accuracy. The known isotopes of thorium range in mass number from 207 to 238.
=== Antimalarial === During WWII a British team led by Frank Rose discovered (see details there) that some biguanides are useful as antimalarial drugs. Much later it was demonstrated that they are prodrugs metabolised into active dihydrotriazine derivatives which, until recently, were believed to work by inhibiting dihydrofolate reductase. Examples include:
For example, efavirenz and nelfinavir are two types of drugs that help decrease the HIV infection in a person's body. When the SNP from exon 26 is coupled with other SNP exons, the drugs have a lower chance of maintaining the HIV infection. Although, when the TT nucleotides in exon 26 are expressed the patient has a lower concentration of the virus but when the genotype morphs into CC or CT the infection is able to spread like normal leaving the MDR 1 gene almost defenseless. These changes in bases of exon 26 for MDR 1 show a correlation between the MDR 1 gene mutations and the ability of the antiretroviral drugs to suppress the HIV infection. Exon 26 has also been studied as to whether it is haplotype dependent or not. The presence of the SNP of exon 26 changes phenotypic functions when it is paired with the presence of mutations from exons 12 and 21. But when acting alone, it does not affect the phenotypic outcome as strongly. An example of exon 26's haplotype dependency is seen when looking at chemotherapy. Since MDR 1 removes drugs from our cells, inhibitors have been used to block MRD 1's ability to remove drugs, thus letting beneficial drugs like chemotherapy and immunosuppressants aid the body in recovery more efficiently. MDR1 has different proteins that help exile these specific drugs from cancer cells. Verapamil and cyclosporine A are common inhibitors for MDR 1.
=== Little Saigon === New York's "Little Saigon", though not officially designated, exists on the Bowery between Grand Street and Hester Street. New York magazine claims that while this street blends in with neighboring Chinatown, the area is filled with Vietnamese restaurants.
Sources: en.wikipedia.org
== Phase 3 == The third phase of the PSI was called PSI:Biology and was intended to reflect the emphasis on the biological relevance of the work. During this phase, highly organized networks of investigators were applying the new paradigm of high-throughput structure determination, which was successfully developed during the earlier phases of the PSI, to study a broad range of important biological and biomedical problems. The network included centers for high-throughput structure determination, centers for membrane protein structure determination, consortia for high-throughput-enabled structural biology partnerships, the SBKB and the PSI-MR. In September 2013 NIH announced that PSI would not be renewed after its third phase would end in 2015.
=== Definitions === Normal serum potassium levels are generally considered to be between 3.5 and 5.3 mmol/L. Levels above 5.5 mmol/L generally indicate hyperkalemia, and those below 3.5 mmol/L indicate hypokalemia.
=== OECD Chief Economist === British economist Christopher Dow served as Chief Economist of the OECD from its establishment until 1973. In 1980, Canadian economist Sylvia Ostry became the first woman to be appointed OECD Chief Economist, holding the position until 1983. In 1992, Kumiharu Shigehara, former Chief Economist of the Bank of Japan, became the first individual from outside the English-speaking world to be appointed OECD Chief Economist. At the time of his appointment, the Financial Times, in an article entitled "Japan’s Turn" (22 January 1992), described him as exemplifying a new generation of Japanese figures characterised by self-confidence, strong international awareness, and a willingness to express their views openly. In February 2026, Italian Stefano Scarpetta was announced as the next Chief Economist. Scarpetta used to lead the Directorate's work on employment, migration and health.
== Protein-derived cofactors == In a number of enzymes, the moiety that acts as a cofactor is formed by post-translational modification of a part of the protein sequence. This often replaces the need for an external binding factor, such as a metal ion, for protein function. Potential modifications could be oxidation of aromatic residues, binding between residues, cleavage or ring-forming. These alterations are distinct from other post-translation protein modifications, such as phosphorylation, methylation, or glycosylation in that the amino acids typically acquire new functions. This increases the functionality of the protein; unmodified amino acids are typically limited to acid-base reactions, and the alteration of resides can give the protein electrophilic sites or the ability to stabilize free radicals. Examples of cofactor production include tryptophan tryptophylquinone (TTQ), derived from two tryptophan side chains, and 4-methylidene-imidazole-5-one (MIO), derived from an Ala-Ser-Gly motif. Characterization of protein-derived cofactors is conducted using X-ray crystallography and mass spectroscopy; structural data is necessary because sequencing does not readily identify the altered sites.
Sources: en.wikipedia.org
Since the 18th century, critics have argued that slavery hinders technological advancement because the focus is on increasing the number of slaves doing simple tasks rather than upgrading their efficiency. For example, it is sometimes argued that, because of this narrow focus, technology in Greece – and later in Rome – was not applied to ease physical labour or improve manufacturing.
In 1979 had 70,000 in 13 states, Illinois being the farthest west. Headquarters in Pittsburgh. Locals are called branches and are affiliated with a Catholic parish. 300 branches in 13 states in 1979. Regional groups are called districts, highest authority is called the "Supreme Assembly", which meets biennially. Opened Knights of St. George Home for the aged and infirm in 1923. Opened Camp Rolling Hills for boys and girls in 1969. The camp was open to non-Catholics. Both establishments are located in Wellsburg, West Virginia. Had an altar boy recognition program that was extended to altar girls in 1978. Scholarships for high school students who have been members of the group for two years are offered. It collects medical supplies from local physicians to ship to missionaries. Has also supported American Federation of Catholic Societies, National Catholic Welfare Council and Catholic Central Verein of America. Adopted graded assessment plan in 1904, adopted an actuarially sound method in 1915. Catholic Workman - Founded in 1891 in St. Paul, Minnesota, by Fr. John Rynda for Czech Catholics. In 1965 there were 19,000 members, 18,000 in 1979. Had 15,000 members. Headquarters in St. Paul, Minnesota. National convention meets quadrennially. In 1978 there were 124 locals and 12 state groups. Absorbed the Western Bohemian Catholic Union in 1930 and the Daughters of Columbus in 1937.
Females are more aggressive than males during the courtship period, often fighting for access to mates, with fights among females accounting for more than half the aggressive interactions during this period. If females court a male that already has a partner, the incumbent female will try to repel the competitor, usually by chasing and kicking. These interactions can be prolonged, lasting up to five hours, especially when the male being fought over is single and neither female has the advantage of incumbency. In these cases, the females typically intensify their calls and displays. The sperm from a mating is stored by the female and can suffice to fertilise about six eggs. The pair mate every day or two, and every second or third day the female lays one of a clutch of five to fifteen very large, thick-shelled, green eggs. The shell is around 1 mm (0.04 in) thick, but rather thinner in northern regions according to indigenous Australians. The shell is substantially composed of calcite, and its δ13C is a function of the emu's diet. The eggs are on average 13 cm × 9 cm (5.1 in × 3.5 in) and weigh between 450 and 650 g (1.0 and 1.4 lb). The maternal investment in the egg is considerable, and the proportion of yolk to albumen, at about 50%, is greater than would be predicted for a precocial egg of this size. This probably relates to the long incubation period which means the developing chick must consume greater resources before hatching. The first verified occurrence of genetically identical avian twins was demonstrated in the emu. The egg surface is granulated and pale green.
Single nucleotide polymorphisms (SNPs) in the MTRR gene impair MTR activity, resulting in elevated homocysteine levels due to compromised methylation to methionine. Elevated homocysteine levels are associated with birth defects in addition to pregnancy complications, cardiovascular disease, cancer, megaloblastic anemia, Alzheimer's diseases and cognitive dysfunction in the elderly. Presence of the mutant variant (66A>G) is associated with significantly lower, up to 4 fold, plasma cobalamin and folate levels in cardiac transplant patients. A consequent decrease in S-adenosylmethionine availability results in DNA hypomethylation. Low folate limits one carbon metabolism and homocysteine metabolism as vitamin B12 interacts with folate in this pathway. Additionally, this mutation is associated with an increased risk in type 2 diabetes.
Physiology of muscle contraction involves several interactions. Myosin filaments act as molecular motors and by binding to actin enables filament sliding. Furthermore, members of the skeletal muscle lipid droplet-associated proteins family associate with other proteins, as activator of adipose triglyceride lipase and its coactivator comparative gene identification-58, to regulate lipolysis in skeletal muscle
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.
Dry powder is normally held at -20 degrees Celsius or below in a sealed, light-protected container with desiccant. Brief room-temperature handling during weighing is generally tolerated. Storage instructions vary between suppliers, so the accompanying certificate of analysis should be followed.