A practical reference on heptapeptide: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2025-11-04. Anything still debated is marked as such rather than presented as settled.
The C-terminal Pro-Gly-Pro extension is not incidental. Proline-rich tails are known to resist several common peptidases, and the published literature attributes the longer half-life of Semax, relative to unmodified ACTH fragments, to this feature. The modification also removes the melanocyte-stimulating and corticosteroidogenic activity that characterizes longer ACTH-derived sequences. Because the molecule is small and hydrophilic, it is typically formulated as an aqueous solution for intranasal or parenteral delivery. Acetylation or amidation at the termini appears in closely related research peptides and shifts the mass by a fixed increment.
Reported pharmacological work centers on neurotrophic signaling, including changes in BDNF and NGF expression in hippocampal tissue in animal models. Human data come largely from studies conducted in Russia, and how well those results generalize to other populations remains an open question. Regulatory status differs sharply by jurisdiction: Semax is a registered prescription medicine in Russia, while it holds no approved marketing status in the United States or the European Union. Outside such jurisdictions it is generally handled as a research chemical, which affects both documentation and quality expectations.
Semax is a synthetic heptapeptide whose sequence is Met-Glu-His-Phe-Pro-Gly-Pro. It was developed as a fragment analog of adrenocorticotropic hormone, modeled specifically on the ACTH(4-10) region. The first four residues reproduce that fragment, while a Pro-Gly-Pro tripeptide is appended at the C-terminus. Work on the compound originated in Russia, where it entered clinical use as an intranasal preparation. Its sequence places it among short regulatory peptides studied for effects on the central nervous system rather than on the adrenal axis.
Practical handling follows from those properties. Bulk material is best divided into single-use portions soon after receipt, because each thaw exposes the whole container to moisture and temperature cycling. Vials should be allowed to reach room temperature before opening to prevent condensation on the powder. Low-binding plasticware reduces loss of dilute solutions, and sterile filtration is used when a preparation must remain free of microbial growth. Records of batch number, reconstitution date and storage history are what allow a later analytical result to be interpreted meaningfully.
Identity and purity of Semax are established mainly by reversed-phase high-performance liquid chromatography coupled with mass spectrometry. The chromatographic trace gives a purity estimate as a percentage of total peak area, while electrospray or matrix-assisted laser desorption ionization confirms the molecular mass against the calculated value. Amino acid analysis and sequence-specific fragmentation provide further confirmation when a supplier's chain of custody is unclear. Vendors frequently quote a purity figure without stating the detection wavelength or the integration method, which limits how far one number can be compared with another.
Stability depends heavily on physical state. Lyophilized powder held dry, cold and dark retains its content over long periods, whereas dissolved peptide begins to change within days at room temperature. The most cited degradation route is oxidation of the methionine residue, which converts the peptide to a sulfoxide form that elutes differently on chromatography. Hydrolysis of amide bonds and adsorption onto container walls contribute smaller losses. Buffers that exclude oxygen from the headspace slow the oxidation pathway, but no single condition prevents all change indefinitely.
| Property | Value | Notes |
|---|---|---|
| Molecular weight | ~813.9 Da (free heptapeptide) | N-acetylated form is about 42 Da heavier |
| Residue count | 7 (heptapeptide) | Four residues from ACTH(4-10), three added |
| Appearance | White to off-white powder | Usually supplied lyophilized |
| Solubility class | Freely soluble in water | Also dissolves in DMSO and polar organic solvents |
| Related parent fragment | ACTH(4-10) | Parent motif is Met-Glu-His-Phe |
Laboratory descriptions of the material are consistent across suppliers. It appears as a white to off-white lyophilized powder that dissolves readily in water and in polar organic solvents such as dimethyl sulfoxide. Aqueous solutions are clear and colorless at low concentrations. Because the peptide contains methionine, oxidation at the sulfur atom is a recognized degradation pathway, and handling notes usually call for protected, desiccated storage. Reported purity for research-grade lots is generally above 95 percent as measured by reversed-phase high-performance liquid chromatography.
The compound is registered in Russia as a pharmaceutical product, most commonly formulated as a nasal solution, and has been used in that setting since the 1990s. Outside that jurisdiction it is generally handled as a research chemical rather than an approved medicine. Regulatory status therefore differs sharply between countries, and material sold internationally may not correspond to the Russian pharmaceutical formulation. Documentation with commercial samples is typically limited to a certificate of analysis covering purity and identity, not clinical status or local legal classification.
Semax is supplied as a lyophilized powder that appears white to off-white. It dissolves readily in water, phosphate-buffered saline, and other aqueous media, which simplifies preparation of working solutions for laboratory use. The nasal products registered in Russia are dilute aqueous solutions, typically around 0.1 percent peptide by weight. Organic solvents are rarely necessary and can complicate handling. Because the peptide is hygroscopic, weighing should be performed quickly and with minimal exposure to ambient humidity.
Solid material is normally kept at minus 20 degrees Celsius in a sealed, desiccated container. Reconstituted solutions are less stable and are usually divided into single-use aliquots before freezing. Repeated freeze-thaw cycles are avoided because they promote aggregation and loss of activity. Light exposure is minimized by using amber glassware or foil wrapping. Published stability data for this peptide are sparse, so recommended storage conditions rest mainly on general practice for short synthetic peptides rather than on dedicated study.
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. It is described in the literature as an analogue of the ACTH(4–10) fragment, a short N-terminal portion of adrenocorticotropic hormone that retains some neurotropic activity without the full hormonal effects of the parent peptide. The molecule carries a methionine residue at the N-terminus and two proline residues near the C-terminus, features that shape both its interactions with receptor systems and its chemical stability. The free peptide corresponds to the formula C37H51N9O10S and a molecular mass near 813.9 Da.
The compound was developed in the 1980s at the Institute of Molecular Genetics in Moscow, where it emerged from research on short ACTH fragments and their effects on the central nervous system. Russian pharmaceutical listings describe it as a nootropic and neuroprotective agent, most often formulated as nasal drops. It is not a marketed medicine in the United States or the European Union, and no pharmacopoeial monograph covers it. Consequently, most published clinical experience with the substance originates from a small number of research centres, mainly in Russia and neighbouring countries.
=== Electronic Submissions Gateway (ESG) === To standardize, automate and streamline the flow of regulatory data, FDA introduced an Electronic Submissions Gateway (ESG) in 2006. This gateway allows reporting organizations to send regulatory submissions to different centers over the internet, packaged in a center-specific format and enveloped as a GNU-compatible .tar.gz file, through either a FDA-specific WebTrader application or via a more generic B2B communication protocol called AS2 (Applicability Statement 2).
=== Chemical dating/ Total Pb dating === Chemical dating requires measuring the elemental abundances of U, Th and Pb but not isotopes. U-Th-total Pb dating, also known as electron microprobe U–Th–Pb dating, measures the elemental abundances of the three elements by an electron microprobe, and calculates the age (t) by the below equation.
Accurate assessment and prediction of fish quality are of main importance to set prices, increase competitiveness, resolve conflicts of interest and prevent food wastage due to conservative product shelf-life estimations. In last years, research in food science and technology has focused on developing new methodologies to predict fish freshness.
=== Tempe satay === Tempeh skewered and grilled as satay. Sate kere (Javanese for 'poor man's satay') from Solo in Central Java is made from fluffy tempe gembus. Ground tempeh can also be made into a thick sauce, such as in sate ambal, a chicken satay from Kebumen, Central Java where tempeh flavored with chili and spices replaces the more common peanut sauce.
== Births == 17 January - William Saunders, poet (died 1851) 1 February - Jane Williams (Ysgafell), writer (died 1885) 9 April - Theophilus Redwood, pharmacist (died 1892) 21 April - Sir George Cornewall Lewis, statesman (died 1863) date unknown Joseph Murray Ince, painter (died 1859) Harry Longueville Jones, archæologist, artist and Inspector of Schools for Wales (died 1870) David Pugh, politician (died 1890) probable - Thomas Rees (Twm Carnabwth), Rebecca rioter (died 1876)
Sources: en.wikipedia.org
The two discover that Tender has been running a round-tripping scheme, falsifying profits by overstating the costs of its acquisitions of third-party payment processors in Ghana and bribing officials to help stage publicity photos. Her findings enable Harper to make a public case against Tender at an investor conference, causing its stock to fall 28%. The Tender short is ultimately successful, netting the fund £110 million, with Sweetpea, Harper and Kwabena distributing £2 million amongst themselves. The three later explore an office for their fund.
According to the Nigerian constitution, all minerals, gas, and oil the country possesses are legally the property of the Nigerian Federal Government. The revenue gained by the NNPC accounts for 76% of federal government revenue and 40% of the entire country's GDP. As of 2000, oil and gas exports account for 98% of Nigerian export earnings.
Cliffe began directly contacting Half-Life mappers and reached out to people who had previously submitted maps to Radium, a Half-Life mapping site. A contest was held to select maps for the initial beta, though some maps selected were later discarded. Before the first beta's official release, a pre-beta build was leaked online, which potentially accelerated the release of the mod. The first beta, released on June 18, 1999, featured a hostage rescue scenario, 9 weapons, 4 maps, and one player model per side. Jess Cliffe reported that the release was well received by the community. Beta 2 and Beta 3 followed, adding new weapons, maps, and factions. Beta 3 introduced the removal of kill counts from the scoreboard, which was controversial and later reversed. Beta 4 introduced the bomb defusal scenario. The interest in the game drew numerous players to Cliffe's website, which helped both him and Le make revenue from advertisements hosted on the site. Another website related to Counter-Strike, a fansite named CS-Nation, was launched by John "rizzuh" Jensen as a source for information about the game, news updates, and skins. In late 1999, Minh Le began working at Barking Dog Studios while finishing his studies. When Valve Software learned of this, they asked Barking Dog to assist in developing Beta 5, offering to finance the project and acquire the game's intellectual property. Barking Dog mainly handled development, as Le was occupied with his university studies. Valve contributed by cleaning up code, fixing bugs, and enhancing the interface.
==== Biomolecules ==== The isotopic composition of biomolecules preserved in the sedimentary record can be used as a proxy for paleoenvironment reconstructions. Since water is the main hydrogen source for photoautotrophs, the HIC of their biomass can be related to the composition of their growth water and thereby used to gain insight into some properties of ancient environments. Studying hydrogen isotopes can be very valuable, as hydrogen is more directly related to climate than other relevant stable isotope systems. However, hydrogen atoms bonded to oxygen, nitrogen, or sulfur are exchangeable with environmental hydrogen, which makes this system less straightforward [ref to earlier H exchange section]. To study the HIC of biomolecules, it is preferable to use compounds where the hydrogen is largely bound to carbon, and thus not exchangeable on experimental timescales. By this criterion, lipids are a much better subject for hydrogen isotope studies than sugars or amino acids. The net fractionation between source water and lipids is denoted εl/w:
Sources: en.wikipedia.org
Hematopoietic stem cells have also been discovered to be travelling in the blood stream and possess equal differentiating ability as other mesenchymal stem cells, again with a very non-invasive harvesting technique. There has been more recent interest in the use of extra embryonic mesenchymal stem cells. Research is underway to examine the differentiating capabilities of stem cells found in the umbilical cord, yolk sac and placenta of different animals. These stem cells are thought to have more differentiating ability than their adult counterparts, including the ability to more readily form tissues of endodermal and ectodermal origin.
== Production == StAR is a mitochondrial protein that is rapidly synthesized in response to stimulation of the cell to produce steroid. Hormones that stimulate its production depend on the cell type and include luteinizing hormone (LH), ACTH and angiotensin II. At the cellular level, StAR is synthesized typically in response to activation of the cAMP second messenger system, although other systems can be involved even independently of cAMP. StAR has thus far been found in all tissues that can produce steroids, including the adrenal cortex, the gonads, the brain and the nonhuman placenta. One known exception is the human placenta. Substances that suppress StAR activity, like those listed below, can cause endocrine disrupting effects, including altered steroid hormone levels and fertility.
ACS Applied Materials & Interfaces. 16 (12): 14633–14644. Bibcode:2024AAMI...1614633K. doi:10.1021/acsami.4c02243. PMC 10982941. PMID 38483312. Karki, Sandeep; Malhotra, Sahil; Ijaz, Muhammad; Rollet, Nicolas; O'Cearbhaill, Eoin D.; Bini, Estela; Brayden, David J. (2026). "A pullulan-based bilayer film for buccal delivery of a GLP-1 peptide analogue". Carbohydrate Polymers. 380 125064. doi:10.1016/j.carbpol.2026.125064. PMID 41831981.
4 Cytc2+ + O2 + 8H+inside → 4 Cytc3+ + 2 H2O + 4H+outside Although the heme proteins are the most important class of iron-containing proteins, the iron–sulfur proteins are also very important, being involved in electron transfer, which is possible since iron can exist stably in either the +2 or +3 oxidation states. These have one, two, four, or eight iron atoms that are each approximately tetrahedrally coordinated to four sulfur atoms; because of this tetrahedral coordination, they always have high-spin iron. The simplest of such compounds is rubredoxin, which has only one iron atom coordinated to four sulfur atoms from cysteine residues in the surrounding peptide chains. Another important class of iron–sulfur proteins is the ferredoxins, which have multiple iron atoms. Transferrin does not belong to either of these classes. The ability of sea mussels to maintain their grip on rocks in the ocean is facilitated by their use of organometallic iron-based bonds in their protein-rich cuticles. Based on synthetic replicas, the presence of iron in these structures increased elastic modulus 770 times, tensile strength 58 times, and toughness 92 times. The amount of stress required to permanently damage them increased 76 times.
=== EC 1.23.1 With NADH or NADPH as donor === EC 1.23.1.1: (+)-Pinoresinol reductasa EC 1.23.1.2: (+)-lariciresinol reductase EC 1.23.1.3: (–)-pinoresinol reductase EC 1.23.1.4: (–)-lariciresinol reductase
Sources: en.wikipedia.org
The sequence is Met-Glu-His-Phe-Pro-Gly-Pro, a seven-residue peptide. The first four residues correspond to the ACTH(4-10) fragment, and Pro-Gly-Pro is added at the C-terminus. N-acetylated versions also appear in the literature and differ in mass.
Semax is a synthetic analog of the ACTH(4-10) fragment rather than a copy of the full hormone. Truncation plus the added tail removes the steroidogenic portion of ACTH. That distinction explains why it is studied for nervous-system effects instead of adrenal stimulation.
It is registered as a prescription product in Russia and has been used there clinically, chiefly by the intranasal route. No approval exists in the United States or the European Union. Availability elsewhere typically falls under research-chemical distribution, with varying purity documentation.
Suppliers normally quote a percentage of total chromatographic peak area, most often from reversed-phase HPLC. That figure says nothing about what the remaining percentage contains, and it depends on the detection wavelength used. A mass spectrometry result is a separate and stronger check on identity.