Tuftsin analog 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.
Updated 2026-06-24. Numbers and descriptions here follow the published literature rather than marketing material.
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.
| Property | Value | Notes |
|---|---|---|
| Peptide sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Seven residues; tuftsin plus a Pro-Gly-Pro tail |
| Molecular formula | C33H57N11O9 | Commonly reported value for the free peptide |
| Monoisotopic mass | Roughly 751.4 Da | Average molecular mass near 751.9 Da |
| Appearance | White to off-white powder | Typically supplied as a lyophilized solid |
| Solubility class | Freely soluble in water | Also dissolves in saline and other polar solvents |
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.
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.
== History == HATU was first reported by Louis A. Carpino in 1993 as an efficient means of preparing active esters derived from 1-hydroxy-7-azabenzotriazole (HOAt). HATU is commonly prepared from HOAt and TCFH under basic conditions and can exist as either the uronium salt (O-form) or the less reactive iminium salt (N-form). HATU was initially reported as the O-form using the original preparation reported by Carpino; however, X-ray crystallographic and NMR studies revealed the true structure of HATU to be the less reactive guanidinium isomer. It is, however, possible to obtain the uronium isomer by preparing HATU using KOAt in place of HOAt and working up the reaction mixture quickly to prevent isomerisation.
== Use in synthesis reactions == D-amino acid dehydrogenase has shown itself to be effective in the synthesis of branched-chain amino acids such as D-leucine, D-isoleucine, and D-valine. In the given study, researchers were successfully able to use D-amino acid dehydrogenase to create high amounts of these products from the starting material of 2-oxo acids, in the presence of ammonia. The conditions for this were variable, though the best results appeared at around 65 °C. Amino Acids obtained through these reactions resulted in a high enantioselectivity of >99% and high yields of >99%. Given the nature of this enzyme, it may be possible to use it in order to create non-branched D-amino acids as well as modified D-amino acids.
== Exceptions == Genetics does not determine the language spoken by a human being, and the link between Y-chromosomal haplogroups and linguistic affinities is an observed correlation and not a causal link. While father tongues predominate, exceptions to father tongues exist in the world. One possible exception is the Balti in northern Pakistan. The mtDNA haplogroups most frequent among Balti are the same as those of the neighbouring Tibetan communities, whereas the Y-chromosomal haplogroups most frequent in Balti males appear to have entered Baltistan from the west with the introduction of Islam. The Balti speak one of the most conservative Tibetan languages. The language of the Balti corresponds to the mtDNA and not to the Y chromosome and is in effect a salient example of a mother tongue.
Low Apgar scores, <5 at 5 minutes and 10 minutes. Floppiness, or unreactive to sights or sounds, or more tense and agitated. Low heart rate. Low blood pressure. Poor muscle tone and absent reflexes. Weak breathing, no breathing at all, or rapid breathing. Need for resuscitation after delivery. Weak cry. Bluish or pale skin color. Excessive acid in the blood. Seizures or abnormal movements. Problems feeding
Sources: en.wikipedia.org
In return, the host provides the symbiont with chemicals required for chemosynthesis, such as carbon, sulfide, and oxygen. In the early stages of studying life at hydrothermal vents, there were differing theories regarding the mechanisms by which multicellular organisms were able to acquire nutrients from these environments, and how they were able to survive in such extreme conditions. In 1977, it was hypothesized that the chemoautotrophic bacteria at hydrothermal vents might be responsible for contributing to the diet of suspension-feeding bivalves. Finally, in 1981, it was understood that giant tubeworm nutrition acquisition occurred as a result of chemoautotrophic bacterial endosymbionts. As scientists continued to study life at hydrothermal vents, it was understood that symbiotic relationships between chemoautotrophs and macrofauna invertebrate species was ubiquitous. For instance, in 1983, clam gill tissue was confirmed to contain bacterial endosymbionts; in 1984 vent bathymodiolid mussels and vesicomyid clams were also found to carry endosymbionts. However, the mechanisms by which organisms acquire their symbionts differ, as do the metabolic relationships. For instance, tubeworms have no mouth and no gut, but they do have a "trophosome", which is where they deal with nutrition and where their endosymbionts are found. They also have a bright red plume, which they use to uptake compounds such as O, H2S, and CO2, which feed the endosymbionts in their trophosome.
== Genes == The MHC locus is present in all jawed vertebrates; it is assumed to have arisen about 450 million years ago. Despite the difference in the number of genes included in the MHC of different species, the overall organization of the locus is rather similar. Usual MHC contains about a hundred genes and pseudogenes, not all of which are involved in immunity. In humans, the MHC region occurs on chromosome 6, between the flanking genetic markers MOG and COL11A2 (from 6p22.1 to 6p21.3 about 29Mb to 33Mb on the hg38 assembly), and contains 224 genes spanning 3.6 megabase pairs (3 600 000 bases). About half have known immune functions. The human MHC is also called the HLA (human leukocyte antigen) complex (often just the HLA). Similarly, there is SLA (Swine leukocyte antigens), BoLA (Bovine leukocyte antigens), DLA for dogs, etc. However, historically, the MHC in mice is called the Histocompatibility system 2 or just the H-2, whereas it has been referred to as the RT1 complex in rats, and the B locus in chickens. The MHC gene family is divided into three subgroups: MHC class I, MHC class II, and MHC class III. Among all those genes present in MHC, there are two types of genes coding for the proteins MHC class I molecules and MHC class II molecules that are directly involved in the antigen presentation. These genes are highly polymorphic, 19031 alleles of class I HLA, and 7183 of class II HLA are deposited for human in the IMGT database.
=== General === In Christian iconography, some works of art depict women with their breasts in their hands or on a platter, signifying that they died as a martyr by having their breasts severed; one example of this is Saint Agatha of Sicily.
Although the negative health consequences of obesity in the general population are well supported by the available research evidence, health outcomes in certain subgroups seem to be improved at an increased BMI, a phenomenon known as the obesity survival paradox. The paradox was first described in 1999 in overweight and obese people undergoing hemodialysis and has subsequently been found in those with heart failure and peripheral artery disease (PAD). In people with heart failure, those with a BMI between 30.0 and 34.9 had lower mortality than those with a normal weight. This has been attributed to the fact that people often lose weight as they become progressively more ill. Similar findings have been made in other types of heart disease. People with class I obesity and heart disease do not have greater rates of further heart problems than people of normal weight who also have heart disease. In people with greater degrees of obesity, however, the risk of further cardiovascular events is increased. Even after cardiac bypass surgery, no increase in mortality is seen in the overweight and obese. One study found that the improved survival could be explained by the more aggressive treatment obese people receive after a cardiac event. Another study found that if one takes into account chronic obstructive pulmonary disease (COPD) in those with PAD, the benefit of obesity no longer exists.
The following general election to the unicameral Riksdag in 1973 gave the Government the support of only 175 members, while the opposition could mobilize an equal force of 175 members. In a number of cases a tied vote ensued, and the final decision had to be determined by lot. To avoid any recurrence of this unstable situation, the number of seats in the Riksdag was reduced to 349, from 1976 onwards.
Sources: en.wikipedia.org
== Coordination chemistry principles == Metalloproteins bind metal ions in one of two ways: either directly by amino acids, or in the form of larger ligands containing metal ions. Metal ions are usually coordinated directly by nitrogen, oxygen or sulfur centers belonging to amino acid residues of the protein. These donor groups are often provided by side-chains on the amino acid residues. Especially important are the imidazole substituent in histidine residues, thiolate substituents in cysteine residues, and carboxylate groups provided by aspartate and glutamate. Given the diversity of the metalloproteome, virtually all amino acid residues have been shown to bind metal centers. The peptide backbone also provides donor groups; these include deprotonated amides and the amide carbonyl oxygen centers. Lead(II) binding in natural and artificial proteins has been reviewed. In addition to donor groups that are provided by amino acid residues, many organic cofactors function as ligands. Perhaps most famous are the tetradentate N4 macrocyclic ligands incorporated into the heme protein and similar porphyrinoid structures. Inorganic ligands such as sulfide and oxide are also common, e.g in iron-sulfur clusters.
The government adopted a strategic hamlets policy of the kind used in Malaya and Vietnam to restrict the influence of insurgents over the population of rural areas. Local people were forced to relocate to protected villages (PVs) which were strictly controlled and guarded by the government against rebel atrocities. The protected villages were compared by the guerrillas to concentration camps. Some contemporary accounts claim that this interference in the lives of local residents induced many of them who had previously been neutral to support the guerrillas. The war degenerated into rounds of increasing brutality from all three parties involved (ZANU and ZAPU, and the Rhodesian Army). Mike Subritzky, a former New Zealand Army ceasefire monitor in Rhodesia, in 1980 described the war as "both bloody and brutal and brought out the very worst in the opposing combatants on all three sides." A major problem for the Rhodesian state in fighting the Bush War was always a shortage of manpower. Of the 3,000 white men liable for conscription in 1973, only about 1,000 reported when called-up. In February 1978, the Rhodesian Army stated it needed a minimum of 1,041 men to continue combat operations, and of those called up, only 570 reported for duty while the rest chose to move to South Africa. White emigration increased as the state called up more and more men to fight in the war, creating a vicious circle, which gradually limited the capacity of the Rhodesian state to continue the war.
Humans use scorpions both practically, for medicine, food, and pets, and symbolically, whether as gods, to ward off harm, or to associate a product or business with the evident power of the small but deadly animal.
== Autism == William Shaw became focused on autism in 1993, and has claimed that acetaminophen may be a major cause of autism. Nevertheless, as of 2017, there still was no good evidence to claim that acetaminophen caused autism. Shaw has also alleged without credible scientific evidence that yeast infections cause autism. He was accused of "exploit[ing] the parents' understandable and desperate search for a cause of their children's autism". Shaw has endorsed dangerous and discredited chelation treatments for autism.
Sources: en.wikipedia.org
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.
No peptide with this exact sequence has been identified as an endogenous substance. It is a laboratory-designed analog of tuftsin, a naturally occurring immunomodulatory tetrapeptide. The Pro-Gly-Pro extension has no known natural source.
Proline introduces conformational constraints that make a peptide less accessible to common peptidases. This is a standard stabilization strategy in peptide design. The added residues also increase the distance between the active tuftsin portion and typical cleavage sites.
The sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, commonly written as TKPRPGP. It shares the first four residues with tuftsin and carries three prolines in the chain. The proline-rich tail is the main structural feature that separates it from the parent tetrapeptide.