A practical reference on Certificate of analysis: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2026-03-23. Anything still debated is marked as such rather than presented as settled.
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.
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.
Published work on this peptide almost always uses intranasal delivery, with drops or a spray applied to the nasal mucosa. Some animal experiments have used subcutaneous or intraperitoneal injection, and a smaller number have compared routes directly. Oral administration is not a focus of the literature, because short peptides of this size are broken down by digestive enzymes and cross intestinal barriers poorly. How much of an intranasal dose reaches the bloodstream intact in humans remains an open question.
Animal studies have examined behaviour in tests of anxiety, memory retention and stress response, and several report changes in neurotrophic or neurotransmitter-related markers. The human evidence base is much smaller, consisting mainly of short trials conducted in Russia with limited reporting in English-language journals. Sample sizes are modest and outcome measures vary between studies, so the findings are best described as preliminary. Independent replication under modern trial standards has not been widely reported.
Outside its country of origin the compound is generally handled as a research chemical rather than an approved medicine. No regulatory approval from the United States Food and Drug Administration or the European Medicines Agency has been granted for human use. Identity and purity are normally checked by reverse-phase high-performance liquid chromatography, with mass spectrometry used to confirm the molecular mass. Lyophilised material is stored cold and desiccated, and repeated freeze-thaw cycles are avoided.
| 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 |
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.
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.
== Role in the immune system == In addition to their role as UV radical scavengers, melanocytes are also part of the immune system, and are considered to be immune cells. Although the full role of melanocytes in immune response is not fully understood, melanocytes share many characteristics with dendritic cells: branched morphology; phagocytic capabilities; presentation of antigens to T-cells; and production and release of cytokines. Although melanocytes are dendritic in form and share many characteristics with dendritic cells, they derive from different cell lineages. Dendritic cells are derived from hematopoietic stem cells in the bone marrow. Melanocytes on the other hand originate from neural crest cells. As such, although morphologically and functionally similar, melanocytes and dendritic cells are not the same. Melanocytes are capable of expressing MHC Class II, a type of MHC expressed only by certain antigen presenting cells of the immune system, when stimulated by interactions with antigen or cytokines. All cells in any given vertebrate express MHC, but most cells only express MHC class I. The other class of MHC, Class II, is found only on "professional" antigen presenting cells such as dendritic cells, macrophages, B cells, and melanocytes. Importantly, melanocytes stimulated by cytokines express surface proteins such as CD40 and ICAM1 in addition to MHC class II, allowing for co-stimulation of T cells. In addition to presenting antigen, one of the roles of melanocytes in the immune response is cytokine production.
In November 1971, Douglas-Home renewed contacts with Salisbury and announced a proposed agreement that would be satisfactory to both sides – it recognised Rhodesia's 1969 constitution as the legal frame of government, while agreeing that gradual legislative representation was an acceptable formula for unhindered advance to majority rule. Nevertheless, the new settlement, if approved, would also implement an immediate improvement in black political status, offer a means to terminate racial discrimination, and provide a solid guarantee against retrogressive constitutional amendments. Implementation of the proposed settlement hinged on popular acceptance, but the Rhodesian government consistently refused to submit it to a universal referendum. A twenty four-member commission headed by an eminent jurist, Lord Pearce, was therefore tasked with ascertaining public opinion on the subject. In 1972, the commission began interviewing interest groups and sampling opinions – although concern was expressed over the widespread apathy encountered. According to the commission, whites were in favour of the settlement, and Rhodesians of Coloured or Asian ancestry generally pleased, while the black response to the settlement's terms was resoundingly negative. As many as thirty black Rhodesian chiefs and politicians voiced their opposition, prompting Britain to withdraw from the proposals on the grounds of the commission's report.
Jostel's TSH index (JTI or TSHI) helps to determine thyrotropic function of anterior pituitary on a quantitative level. It is reduced in thyrotropic insufficiency and in certain cases of non-thyroidal illness syndrome. It is calculated with
Sources: en.wikipedia.org
== Function == YAP1 is a transcriptional co-activator and its proliferative and oncogenic activity is driven by its association with the TEAD family of transcription factors, which up-regulate genes that promote cell growth and inhibit apoptosis. Several other functional partners of YAP1 were identified, including RUNX, SMADs, p73, ErbB4, TP53BP2, LATS1/2, PTPN14, AMOTs, and ZO1/2. YAP1 and its close paralog, TAZ (WWTR1), are the main effectors of the Hippo tumor suppressor pathway. When the pathway is activated, YAP1 and TAZ are phosphorylated on a serine residue and sequestered in the cytoplasm by 14-3-3 proteins. When the Hippo pathway is not activated, YAP1/TAZ enter the nucleus and regulate gene expression. It is reported that several genes are regulated by YAP1, including Birc2, Birc5, connective tissue growth factor (CTGF), amphiregulin (AREG), Cyr61, Hoxa1 and Hoxc13. YAP/TAZ have also been shown to act as stiffness sensors, regulating mechanotransduction independently of the Hippo signalling cascade. As YAP and TAZ are transcriptional co-activators, they do not have DNA-binding domains. Instead, when inside the nucleus, they regulate gene expression through TEAD1-4 which are sequence-specific transcription factors that mediate the main transcriptional output of the Hippo pathway. The YAP/TAZ and TEAD interaction competitively inhibits and actively dissociates the TEAD/VGLL4 interaction which functions as a transcriptional repressor.
FGF-1 stimulates the proliferation and differentiation of all cell types necessary for building an arterial vessel, including endothelial cells and smooth muscle cells; this fact distinguishes FGF-1 from other pro-angiogenic growth factors, such as vascular endothelial growth factor (VEGF), which primarily drives the formation of new capillaries. Besides FGF-1, one of the most important functions of fibroblast growth factor-2 (FGF-2 or bFGF) is the promotion of endothelial cell proliferation and the physical organization of endothelial cells into tube-like structures, thus promoting angiogenesis. FGF-2 is a more potent angiogenic factor than VEGF or PDGF (platelet-derived growth factor); however, it is less potent than FGF-1. As well as stimulating blood vessel growth, aFGF (FGF-1) and bFGF (FGF-2) are important players in wound healing. They stimulate the proliferation of fibroblasts and endothelial cells that give rise to angiogenesis and developing granulation tissue; both increase blood supply and fill up a wound space/cavity early in the wound-healing process.
=== Plants === In plants, ADH catalyses the same reaction as in yeast and bacteria to ensure that there is a constant supply of NAD+. Maize has two versions of ADH – ADH1 and ADH2, Arabidopsis thaliana contains only one ADH gene. The structure of Arabidopsis ADH is 47%-conserved, relative to ADH from horse liver. Structurally and functionally important residues, such as the seven residues that provide ligands for the catalytic and noncatalytic zinc atoms, however, are conserved, suggesting that the enzymes have a similar structure. ADH is constitutively expressed at low levels in the roots of young plants grown on agar. If the roots lack oxygen, the expression of ADH increases significantly. Its expression is also increased in response to dehydration, to low temperatures, and to abscisic acid, and it plays an important role in fruit ripening, seedlings development, and pollen development. Differences in the sequences of ADH in different species have been used to create phylogenies showing how closely related different species of plants are. It is an ideal gene to use due to its convenient size (2–3 kb in length with a ≈1000 nucleotide coding sequence) and low copy number.
Owing to Somalia's proximity to the equator, there is little seasonal variation in climate. Hot conditions prevail year-round, with periodic monsoon winds and irregular rainfall. Mean daily maximum temperatures range from 30–40 °C (86–104 °F), except at higher elevations along the eastern seaboard, because of a cold offshore current. In Mogadishu, average afternoon highs range from 28–32 °C (82–90 °F) in April. Some of the highest global mean annual temperatures were recorded in the country; Berbera on the northwestern coast has an average afternoon high of more than 38 °C (100 °F) from June through September. Nationally, mean daily minimums usually vary from about 15–30 °C (59–86 °F). The greatest range in climate occurs in northern Somalia, where temperatures sometimes surpass 45 °C (113 °F) in July on the littoral plains and drop below the freezing point during December in the highlands. In this region, relative humidity ranges from about 40% in the mid-afternoon to 85% at night, changing according to the season. Unlike the climates of most other countries at this latitude, conditions in Somalia range from arid in the northeastern and central regions to semiarid in the northwest and south. In the northeast, annual rainfall is less than 100 mm (4 in); in the central plateaus, it is about 200 to 300 mm (8 to 12 in). The northwestern and southwestern parts of the nation, receive considerably more rain, with an average of 510 to 610 mm (20 to 24 in) per year. Although the coastal regions are hot and humid throughout the year, the hinterland is typically dry and hot.
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.
Most published work uses intranasal application, either as drops or as a nasal spray. Injection routes appear in a smaller set of animal experiments. Oral use is uncommon in the literature because peptide breakdown and poor absorption limit this route.