The short version of reverse-phase HPLC fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-01-14 and is reviewed periodically as new material appears.
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.
Dry powder is normally held at -20 degrees Celsius or lower, in a sealed container with desiccant and protection from light. Reconstituted solutions are usually kept at 2 to 8 degrees Celsius for short periods and frozen for longer ones. Proline residues at several positions are generally associated with some resistance to peptidase attack, but chemical stability still declines at neutral to alkaline pH and at elevated temperature. Exact shelf-life figures are product-specific and are not standardised across suppliers.
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.
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.
Reverse-phase high-performance liquid chromatography with ultraviolet detection near 214 nanometres is the standard purity method. Mass spectrometry, typically electrospray ionisation, confirms identity through the expected mass-to-charge pattern. Amino acid analysis can verify composition independently. Chiral purity requires separate techniques such as derivatisation followed by chromatographic separation, and such data are rarely reported for research-grade material.
Quantification in biological matrices relies on liquid chromatography coupled to tandem mass spectrometry with stable-isotope internal standards. Low plasma concentrations and adsorption to container surfaces both complicate measurement. Solid-phase extraction is often needed to reduce matrix interference before injection. Reported limits of quantification differ widely between laboratories, which makes direct comparison of pharmacokinetic results difficult and limits meta-analysis.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Lyophilised solid form |
| Solubility class | Freely soluble in water | Hydrophilic heptapeptide |
| Dry storage temperature | -20 degrees Celsius or lower | Sealed, desiccated, protected from light |
| Solution storage | 2 to 8 degrees Celsius short term | Avoid repeated freeze-thaw cycles |
| Common identification method | Reversed-phase HPLC with mass spectrometry | Confirms purity and molecular mass |
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.
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 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.
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.
=== Second generation === In 1976, 24-year-old Rich Snyder became the company president after his father's death. Along with his brother Guy, Rich had begun working in his father's In-N-Outs at an early age. Over the next 20 years, the chain experienced a period of rapid growth under Rich's leadership, expanding to 93 restaurants. In June 1988, In-N-Out opened its 50th location, in Thousand Palms, California. The first location outside of the Los Angeles metropolitan area opened in San Diego County in 1990, the 57th location in the chain. In 1992, In-N-Out opened its first non-Southern California restaurant, in Las Vegas, Nevada. Its first Northern California location opened the following year in Modesto. Expansion then spread to Northern California, including the San Francisco Bay Area, while additional Las Vegas-area restaurants were added. After opening the 93rd In-N-Out store in Fresno, California, on December 15, 1993, Rich Snyder and four other passengers died in a plane crash on approach to John Wayne Airport in Orange County, California. Upon Rich Snyder's death, Guy Snyder assumed the presidency in January 1994 and continued the company's aggressive expansion until he died from an overdose of painkillers in 1999. Under his leadership, In-N-Out's 100th location was opened in Gilroy, California, on November 10, 1994. He was president for nearly six years, expanding In-N-Out from 93 to 140 locations. His mother Esther subsequently took over the presidency.
== Cell cycle control == Cell cycle progression is controlled by ordered action of cyclin-dependent kinases (CDKs), activated by specific cyclins that demarcate phases of the cell cycle. Mitotic cyclins, which persist in the cell for only a few minutes, have one of the shortest life spans of all intracellular proteins. After a CDK-cyclin complex has performed its function, the associated cyclin is polyubiquitinated and destroyed by the proteasome, which provides directionality for the cell cycle. In particular, exit from mitosis requires the proteasome-dependent dissociation of the regulatory component cyclin B from the mitosis promoting factor complex. In vertebrate cells, "slippage" through the mitotic checkpoint leading to premature M phase exit can occur despite the delay of this exit by the spindle checkpoint. Earlier cell cycle checkpoints such as post-restriction point check between G1 phase and S phase similarly involve proteasomal degradation of cyclin A, whose ubiquitination is promoted by the anaphase promoting complex (APC), an E3 ubiquitin ligase. The APC and the Skp1/Cul1/F-box protein complex (SCF complex) are the two key regulators of cyclin degradation and checkpoint control; the SCF itself is regulated by the APC via ubiquitination of the adaptor protein, Skp2, which prevents SCF activity before the G1-S transition. Individual components of the 19S particle have their own regulatory roles.
=== Regulation === In order to ensure proper functioning, Wnt signaling is constantly regulated at several points along its signaling pathways. For example, Wnt proteins are palmitoylated. The protein porcupine mediates this process, which means that it helps regulate when the Wnt ligand is secreted by determining when it is fully formed. Secretion is further controlled with proteins such as GPR177 (wntless) and evenness interrupted and complexes such as the retromer complex. Upon secretion, the ligand can be prevented from reaching its receptor through the binding of proteins such as the stabilizers Dally and glypican 3 (GPC3), which inhibit diffusion. In cancer cells, both the heparan sulfate chains and the core protein of GPC3 are involved in regulating Wnt binding and activation for cell proliferation. Wnt recognizes a heparan sulfate structure on GPC3, which contains IdoA2S and GlcNS6S, and the 3-O-sulfation in GlcNS6S3S enhances the binding of Wnt to the heparan sulfate glypican. A cysteine-rich domain at the N-lobe of GPC3 has been identified to form a Wnt-binding hydrophobic groove including phenylalanine-41 that interacts with Wnt. Blocking the Wnt binding domain using a nanobody called HN3 can inhibit Wnt activation. At the Fz receptor, the binding of proteins other than Wnt can antagonize signaling. Specific antagonists include Dickkopf (Dkk), Wnt inhibitory factor 1 (WIF-1), secreted Frizzled-related proteins (SFRP), Cerberus, Frzb, Wise, SOST, and Naked cuticle. These constitute inhibitors of Wnt signaling. However, other molecules also act as activators.
In 1977, British political scientist Hedley Bull published his work The Anarchical Society, which proposed that international relations between states existed in a kind of anarchy, without a higher authority to mediate between them.
Sources: en.wikipedia.org
The Pharmacyclics name was retained, and it operated as a subsidiary of AbbVie from its previous Sunnyvale, California headquarters until the consolidation of AbbVie Bay Area sites in a new building in South San Francisco. In June 2015, AbbVie and Halozyme Therapeutics entered into a global collaboration and licensing agreement to develop and commercialize products that combine AbbVie's treatments and Halozyme's ENHANZE drug-delivery technology, this was terminated in November 2016. In February 2016, AbbVie and Cambridge, Massachusetts-based Synlogic announced a multi-year R&D collaboration. Synlogic is a synthetic biology company built on research from the labs of James Collins and Tim Lu at MIT. As part of the collaboration, AbbVie is getting worldwide rights to Synlogic's probiotic-based technology for treating inflammatory bowel disease, and the research teams will focus on Crohn's disease and ulcerative colitis. In April 2016, the company announced it would acquire Stemcentrx for up to $9.8 billion. A day later, the company announced an expansion of a two and a half-year-old cystic fibrosis deal with Galapagos NV, potentially doubling milestone payments to $600 million. Also in April 2016, the company partnered with the University of Chicago to investigate several areas of oncology: breast, lung, prostate, colorectal and hematological cancers. Also in April 2016, the company announced it would co-commercialize Argenx's preclinical immunotherapy, ARGX-115.
Molybdenum is a chemical element; it has symbol Mo and atomic number 42. The name is derived from Ancient Greek μόλυβδος mólybdos, meaning lead, since its ores were sometimes confused with those of lead. Molybdenum minerals have been known throughout history, but the element was discovered (in the sense of differentiating it as a new entity from the mineral salts of other metals) in 1778 by Carl Wilhelm Scheele. The metal was first isolated in 1781 by Peter Jacob Hjelm. Molybdenum does not occur naturally as a free metal on Earth; in its minerals, it is found only in oxidized states. The free element, a silvery metal with a grey cast, has the sixth-highest melting point of any element. It readily forms hard, stable carbides in alloys, and for this reason most of the world production of the element (about 80%) is used in steel alloys, including high-strength alloys and superalloys. Most molybdenum compounds have low solubility in water. Heating molybdenum-bearing minerals under oxygen and water affords molybdate ion MoO2−4, which forms quite soluble salts. Industrially, molybdenum compounds (about 14% of world production of the element) are used as pigments and catalysts. Molybdenum-bearing enzymes are by far the most common bacterial catalysts for breaking the chemical bond in atmospheric molecular nitrogen in the process of biological nitrogen fixation. At least 50 molybdenum enzymes are now known in bacteria, plants, and animals, although only bacterial and cyanobacterial enzymes are involved in nitrogen fixation.
== Autobiographical nature == A Scanner Darkly is a fictionalized account of real events, based on Dick's experiences in the 1970s drug culture. Dick said in an interview, "Everything in A Scanner Darkly I actually saw." Between mid-1970 (when his fourth wife Nancy left him) and mid-1972, Dick lived semi-communally with a rotating group of mostly teenage drug users at his home in Marin County, described in a letter as being located at 707 Hacienda Way, Santa Venetia. Dick explained, "[M]y wife Nancy left me in 1970. I got mixed up with a lot of street people, just to have somebody to fill the house. She left me with a four-bedroom, two-bathroom house and nobody living in it but me. So I just filled it with street people and I got mixed up with a lot of people who were into drugs." During this period, the author ceased writing completely and became fully dependent upon amphetamines, which he had been using intermittently for many years. "I did take amphetamines for years in order to be able to—I was able to produce 68 final pages of copy a day," Dick said. The character of Donna was inspired by an older teenager who became associated with Dick sometime in 1970; though they never became lovers, the woman was his principal female companion until early 1972, when Dick left for Canada to deliver a speech to a Vancouver science fiction convention. This speech, "The Android and the Human", served as the basis for many of the recurring themes and motifs in the ensuing novel.
Sources: en.wikipedia.org
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.
Reversed-phase HPLC establishes purity, while mass spectrometry confirms the expected molecular mass. Sequence confirmation may use tandem mass spectrometry or peptide mapping. A certificate of analysis typically reports these results alongside the analytical method applied.
In Russia it is a registered medicine available by prescription. In many other countries it is not approved for human use and is supplied only as a research chemical. Import and possession rules differ by jurisdiction, and buyers are responsible for checking local requirements.
Dry powder is best kept sealed, protected from light, and held at minus 20 degrees Celsius or below. Desiccant packaging helps limit moisture uptake because the material is hygroscopic. A sealed vial should be allowed to equilibrate to room temperature before opening to reduce condensation.