A practical reference on peptidase cleavage: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2025-10-01. Anything still debated is marked as such rather than presented as settled.
Routine characterization relies on reversed-phase high-performance liquid chromatography to establish purity and on mass spectrometry to confirm molecular identity. Electrospray ionization and matrix-assisted laser desorption ionization are both used for mass verification. Amino acid analysis and peptide mapping can detect sequence errors. Common impurities include truncated sequences, methionine sulfoxide formed by oxidation, and deamidated products. Chromatograms are usually recorded near 214 nm, where the peptide backbone absorbs, and purity is reported as the percentage area of the principal peak.
Verification of a supplied batch generally combines a certificate of analysis with independent testing, because certificates are self-reported documents. A typical package includes a chromatographic trace, a mass spectrum, and a stated water or counter-ion content. Batch-to-batch consistency matters more than a single purity figure when results are compared across experiments. No single mandatory standard governs research-grade peptide release, so laboratories are expected to define their own acceptance criteria. Residual trifluoroacetate from purification is a frequently overlooked counter-ion.
Lyophilized material is chemically stable for extended periods when kept dry, cold, and protected from light. The powder is hygroscopic, so vials should be warmed to room temperature before opening to reduce condensation on the contents. Once dissolved, the peptide is far less stable because peptide bonds are susceptible to hydrolysis and the methionine residue can oxidize. Solutions are typically aliquoted and held at 2-8 °C for short intervals or frozen for longer ones, and repeated freeze-thaw cycles should be avoided.
Terminology around the compound varies by source. It appears in catalogues and papers as Semax, as the heptapeptide ACTH(4-7)-Pro-Gly-Pro, and under various alphanumeric laboratory codes used by individual suppliers. These names refer to the same sequence but may imply different salt forms, purity grades, or counter-ions. Peptide databases usually list the free base mass, while product descriptions sometimes report acetate or trifluoroacetate salts with a different formula weight. Because naming conventions for research peptides are not standardised across vendors, checking the declared sequence and measured mass is more reliable than relying on a trade name alone.
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. Its design combines the ACTH(4-7) core fragment with a C-terminal Pro-Gly-Pro extension, a modification intended to improve stability and prolong activity. The molecule is hydrophilic, carries no lipid chains or glycosylation, and has a theoretical mass just over 810 daltons in its free form. All seven residues are proteinogenic amino acids, so no non-natural building blocks appear in the backbone. A free N-terminal methionine and C-terminal proline define the unmodified parent peptide.
| Property | Value | Notes |
|---|---|---|
| Typical purity | 95% or higher | By reversed-phase HPLC area |
| Identity method | Electrospray mass spectrometry | Confirms molecular mass |
| Purity method | Reversed-phase HPLC | Detection near 214 nm |
| Primary degradation | Methionine oxidation | Sulfoxide product, +16 Da |
| Solution storage | 2-8 °C, short term | Aliquot to avoid freeze-thaw |
Circulation time for the peptide is short because peptidases cleave it readily. The Pro-Gly-Pro tail is thought to slow breakdown compared with the bare ACTH fragment, but the gain appears modest. Absorption after intranasal dosing is limited, and only a fraction of a dose is expected to reach the central nervous system. Laboratory concentrations therefore sit well above levels achieved systemically, a gap that complicates translation from bench findings to clinical claims.
The mechanisms attributed to semax are inferred from animal and cell studies rather than traced to one confirmed target. The most frequently cited pathway involves increased expression of brain-derived neurotrophic factor and nerve growth factor in hippocampal and cortical tissue. Some work points to engagement of melanocortin receptors, particularly MC4, which the parent ACTH fragment can activate. Effects on dopaminergic and serotonergic signalling have also been reported. No single account explains all observed results, and the relative weight of each pathway remains unsettled.
The proposed mechanism centres on neurotrophic signalling rather than direct receptor activation. Semax is reported to increase expression of brain-derived neurotrophic factor and nerve growth factor in several brain regions, and to shift the balance between excitatory and inhibitory neurotransmitter systems. Interaction with melanocortin receptors has been suggested because of the parent ACTH fragment. Many of these findings come from rodent studies, and the extent to which they translate to human physiology remains an open question.
Scientific literature on semax is unevenly distributed. A substantial share of published work originates from a small number of laboratories in Russia, while independent replication elsewhere is limited. Human data consist mostly of small trials with short follow-up, and several reported outcomes rely on subjective rating scales. Questions about how much intact peptide reaches the central nervous system after nasal administration, and how long it persists there, are still unresolved. The compound is best described as an active research subject rather than a settled pharmacological agent.
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. It was derived from the ACTH(4-10) fragment, a short segment of adrenocorticotropic hormone that lacks the hormonal activity associated with the full-length peptide. Researchers at the Institute of Molecular Genetics in Moscow developed the compound during the 1980s. It has been registered as a pharmaceutical product in Russia and several neighbouring countries, where it is supplied as a nasal solution, and it is also sold internationally as a research chemical.
从分子层面看，Semax 是线性七肽，没有二硫键、糖基或脂链修饰，N 端为游离氨基，C 端为游离羧基。分子含组氨酸与谷氨酸侧链，因此在水和甲醇等极性溶剂中溶解良好，在非极性溶剂中溶解有限。计算分子量约为 814 Da，与其质子化离子的质荷比吻合，可用于质谱确认。
稳定性主要由水解与氧化两条路径支配。肽键在中性或弱酸性条件下相对稳定，遇到强碱或长时间高温则明显断裂；甲硫氨酸侧链容易被氧化成亚砜，使主峰前移并拉低实际含量。金属离子、光照和反复冻融会进一步促进降解或聚集。冻干粉在低温避光条件下可存放较长时间，配制后的水溶液通常需要冷藏并尽快用完。
Semax is a synthetic heptapeptide developed in the Soviet Union during the 1980s by researchers at the Institute of Molecular Genetics in Moscow. It was designed as a truncated analog of adrenocorticotropic hormone, retaining only the fragment spanning residues four through ten. Investigators sought a peptide that would preserve the cognitive effects associated with ACTH while eliminating the hormonal stimulation of the adrenal cortex. The compound entered clinical use in Russia during the following decade.
Russian regulatory authorities approved the peptide for nasal administration, and it remains listed in the national pharmacopoeia under several trade names. Documented indications include acute ischemic stroke, transient ischemic attacks, traumatic brain injury, and certain ophthalmological and neurological conditions. Physicians also prescribe it for cognitive complaints in older patients, although the evidence base for that use is thinner. Outside Russia and a few neighboring states, the substance is not an approved medicine and is sold instead as a research chemical.
Later generations of the molecule include an N-acetylated form and an amidated form, both marketed online alongside the parent peptide. These variants differ in terminal chemistry and stability, and they are frequently discussed in the same breath even though they have not been compared in controlled trials. Supply outside formal healthcare systems comes largely from laboratories that synthesize peptides to order. Purity and identity of these materials vary widely, and no single body oversees the international trade.
Like many bipedal dinosaurs, T. rex was historically depicted as a 'living tripod', with the body at 45 degrees or less from the vertical and the tail dragging along the ground, similar to a kangaroo. This concept dates from Joseph Leidy's 1865 reconstruction of Hadrosaurus, the first to depict a dinosaur in a bipedal posture. In 1915, convinced that the creature stood upright, Henry Fairfield Osborn, former president of the American Museum of Natural History, further reinforced the notion in unveiling the first complete T. rex skeleton arranged this way. It stood in an upright pose for 77 years, until it was dismantled in 1992. By 1970, scientists realized this pose was incorrect and could not have been maintained by a living animal, as it would have resulted in the dislocation or weakening of several joints, including the hips and the articulation between the head and the spinal column. The inaccurate AMNH mount inspired similar depictions in many films and paintings (such as Rudolph Zallinger's famous mural The Age of Reptiles in Yale University's Peabody Museum of Natural History) until the 1990s, when films such as Jurassic Park introduced a more accurate posture to the general public. Modern representations in museums, art, and film show T. rex with its body approximately parallel to the ground with the tail extended behind the body to balance the head. To sit down, Tyrannosaurus may have settled its weight backwards and rested its weight on a pubic boot, the wide expansion at the end of the pubis in some dinosaurs.
== Metabolism == As first discovered in 1882, pyroglutamic acid can be formed by heating glutamic acid at 180 °C, which results in the loss of a molecule of water. In living cells, it is derived from glutathione through the action of an enzyme, γ-glutamyl cyclotransferase. Pyroglutamic acid may function in glutamate storage, and acts to oppose the action of glutamate, including in the brain. It also acts on the brain's cholinergic system; Amyloid β containing pyroglutamic acid is increased in Alzheimer's disease; this may be part of the disease process. Increased levels of pyroglutamic acid in the blood, leading to excess in the urine (5-oxoprolinuria), can occur following paracetamol overdose, as well as in certain inborn errors of metabolism, causing high anion gap metabolic acidosis. Pyroglutamic acid is a natural humectant in skin, and part of its natural moisturizing factor (NMF). Pyroglutamic acid is also present as the N-terminal amino acid in orexin-A, a peptide involved in wakefulness, among other things.
=== Pharmacokinetics === GBL is rapidly converted into GHB by paraoxonase (lactonase) enzymes, found in the blood. Animals which lack these enzymes exhibit no effect from GBL. GBL is more lipophilic (fat soluble) than GHB, and so is absorbed faster and has higher bioavailability. Because of these pharmacokinetic differences, GBL tends to be more potent and faster-acting than GHB, but has a shorter duration; whereas the related compound 1,4-butanediol (1,4-B) tends to be slightly less potent and slower to take effect but longer-acting than GHB.
=== Background === Mogo is a sentient and living planet. When it is desired, its affiliation with the Corps is shown with foliage arranged into a green band, marked with the standard Green Lantern Corps lantern symbol, circling Mogo's equator. In its early appearances, Mogo is not a social Green Lantern and its interactions with the rest of the DC universe are not well documented. It avoids announcing its presence, preferring to represent itself using pseudonymous holograms. In Mogo's first appearance, it is explained that the planet-sized Mogo's gravitational field would wreak havoc on any other planet it would try to "visit", hence Mogo "doesn't socialize". At the same time, Mogo has allowed alien races to live on its surface and has been willing to change its conditions to suit them. When Parallax, possessing Hal Jordan, destroys the power battery on Oa and kills the Guardians, Mogo loses contact with the Green Lantern energy that helped sustain him. Without energy, Mogo loses consciousness and drifts through Sector 1014 until he is discovered by a nomadic alien race, who strip Mogo of his natural resources and pollute his environment. Mogo's body reacts instinctively, creating constructs to hinder the aliens' efforts to exploit his resources. Mogo is finally rescued by Kyle Rayner, who uses his power ring to reawaken him. With the restoration of the Green Lantern Corps, Mogo has taken on the role of a training and recreation planet for his fellow Green Lanterns. Soranik Natu, Kyle Rayner, and other Lanterns have traveled to his sector to ask for his counsel.
== History == In 1844, Theodor Wertheim separated by steam distillation a pungent-smelling substance from garlic and named it "allyl sulfur." However, only in 1892 could Friedrich Wilhelm Semmler identify diallyl disulfide as one of the components of distilled garlic oil. The natural precursor of diallyl disulfide, allicin, was discovered in 1944 by Chester J. Cavallito and John Hays Bailey. In 1947, A. Stoll and E. Seebeck found that allicin in turn can be produced from the cysteine derivative alliin using the enzyme alliinase.
Sources: en.wikipedia.org
=== RUNASUR === By December 2021, former Bolivian president Evo Morales announced the second summit of RUNASUR to be held in Cusco. The announcement generated various criticisms, with 11 Peruvian diplomats issuing a public statement denouncing RUNASUR as "a clear external threat to sovereignty, independence and national security" because it could be an instrument through which Bolivia would obtain access to the sea, and urging the government not to allow the summit to take place. In addition, it became known that the Revolutionary Agrarian Federation of Cusco (FARTAC), one of RUNASUR's organizers, advocated for the presence of the Movement for Socialism (MAS) party in Peru, and that the party, then led by Morales, had established a branch in the city of Cusco under the leadership of the Bolivian Isabel Ara Condori. Four trips by Morales to Peru since Castillo's victory in the 2021 elections were reported, during which he met with Castillo and Vladimir Cerrón, leader of Perú Libre. In November of that same year, the foreign relations committee of the Peruvian congress declared Morales a persona non grata for interference in the country's internal politics and the carrying out of proselytizing actions "clearly detrimental to the interests of the Peruvian people". The foreign ministry issued a statement declaring that the RUNASUR summit was not linked to the government. Ultimately, the summit was never held.
== Research and Discoveries == Strahl is a pioneer in the field of epigenetics, with contributions to the study of Chromatin biology. As a postdoctoral fellow in C. David Allis’ laboratory, helped to establish the identity of the first lysine and arginine histone methyltransferases and how they contribute to transcriptional activation and heterochromatin formation. Some examples include the discovery of the first histone methyltransferases that target lysine 4 (Set1), lysine 9 (SUV39H1), and lysine 36 of histone H3 (Set2/SETD2) and arginine 3 of histone H4 (PRMT1). Strahl also helped to develop the first antibodies for methylated histones in the Allis laboratory. In 2000, Strahl and Allis put forward the idea of the “histone code hypothesis”, which aimed to explain how multiple histone modifications function together to control chromatin structure and function. The early years of the Strahl laboratory, research focused on the roles of histone methylation and histone ubiquitylation in gene transcription. He linked histone H2B ubiquitylation to the regulation of H3 lysine 79 methylation and in transcriptional elongation and determined how H3 lysine 36 methylation is coupled to RNA Polymerase II and repressive chromatin during transcription elongation. His group also defined the key roles of several histone chaperones (e.g., Spt6) that function in transcription In more recent years, Strahl turned his attention to how chromatin-associated proteins engage histones and their modifications.
=== Preclinical === 2-Bromo-LSD (bromolysergide; BOL-148; BETR-001, TD-0148A) – non-hallucinogenic serotonin 5-HT2A receptor agonist and other actions ART-2612 (ART2612) – FABP5 inhibitor [25] BMB-202 – serotonin 5-HT2A receptor agonist [26] Cycloserine/lurasidone (NRX-101) – combination of cycloserine (NMDA receptor partial agonist) and lurasidone (atypical antipsychotic or non-selective monoamine receptor modulator) [27] Cyproheptadine/prazosin (KT-110; Periactine/Alpress) – combination of cyproheptadine (H1 receptor antagonist, muscarinic acetylcholine receptor antagonist, serotonin receptor antagonist, other actions) and prazosin (α1-adrenergic receptor antagonist) [28] GM-3009 (ibogaine analogue(s); GMX-3009) – various actions Leu-enkephalin (leucine enkephalin; Envelta; METDoloron; NES-100; NM-0127; NM-127; PES200) – δ-opioid receptor agonist [29] Metyrapone/oxazepam (EMB-001C; EMB-001) – combination of metyrapone (11β-hydroxylase inhibitor, antiglucocorticoid) and oxazepam (GABAA receptor positive allosteric modulator, benzodiazepine) Midomafetamine microneedle transdermal patch (MDMA; "ecstasy") – serotonin–norepinephrine–dopamine releasing agent, weak serotonin 5-HT2 receptor agonist, and entactogen NB-127 – undefined mechanism of action [30] NNI-351 – DYRK kinase inhibitor, nerve growth factor (NGF) stimulant [31] Prabotulinumtoxin A (ABP-450; DWP-450; Evosyal; Jeuveau; Nabota; Nuceiva) – acetylcholine release inhibitor and neuromuscular blocking agent [32] Research programme: neurotransmitter modulators - Awakn Life Sciences (AWKN-SDN-14) – serotonin–norepinephrine–dopamine reuptake inhibitors [33] TN-001 – non-hallucinogenic serotonin 5-HT2A receptor partial agonist and serotonin 5-HT2B receptor antagonist and neuroplastogen
Abu Abdurrahman Shishani Abdul-Malik Shishani Abdul-Hakim Shishani Hamza Shishani Abu Al-Bara al-Kavkazi Muslim Shishani Abu Turab Shishani Umar Shishani Tarkhan Gaziev Sayfullakh Shishani Salahuddin Shishani Hayrullah Shishani Sayful-Islam Shishani Naib Shishani Mohannad Shishani Muhammad Shishani Al Bara Shishani Abu Bakr Shishani Halid Shishani Ali Shishani Abu Musa al Shishani ISIS supporters
==== Montessori ==== Prince George's County Public Schools has implemented two facilities dedicated to the Montessori instructional program — the Robert Goddard Montessori School and the John Hanson Montessori School. As dedicated facilities, these schools do not have a neighborhood attendance area. Entry into the program is through the random lottery application process only. The Montessori Primary Program for children ages 3 to 6 years old is based on the Montessori educational philosophy. Taught by Montessori accredited teachers, young children are guided in developing an inner discipline, strengthening their coordination, and extending their concentration span. These accomplishments result with their readily learning to read, write and grasp mathematics. The program consists of a half-day morning for preschoolers (ages 3 ). Children older than four must be enrolled in a certified Montessori program to be accepted into the program. The Montessori Lower Elementary Program is designed for students ages 6 to 9 years old with prior Montessori experience. Rapid growth and learning is observed in classrooms filled with appropriate educational materials. The Montessori Upper Elementary Program continues for the next age grouping of students ages 9–12 with prior Montessori experience. Taught by Montessori accredited teachers, these elementary program students study an integrated curriculum that includes: mathematics, geometry, language, cultural studies, astronomy, biology, chemistry, geography, history, geology, philosophy, art, music and physical education.
Sources: en.wikipedia.org
In 1998, after 38 years of ownership, Monaghan announced his retirement, sold 93 percent of the company to Bain Capital, Inc. for about $1 billion, and ceased being involved in day-to-day operations of the company. A year later, the company named Dave Brandon as its CEO.
===== MHCI presentation ===== In the simplified view of this pathway HSPs are usually not mentioned: antigenic peptides are generated in proteasome, transported into ER through protein transporter TAP and loaded onto MHCI, which then goes through secretory pathway on plasma membrane. But HSPs play an important part in transfer of unfolded proteins to proteasome and generated peptides to MHCI. Hsp90 can associate with proteasome and take over generated peptides. Afterwards, it can associate with hsp70, which can take the peptide further to the TAP. After passing through TAP, ER chaperons are getting important - calreticulin binds peptides and together with gp96 form peptide loading complex for MHCI. This handing over with peptides is important, because HSPs can shield hydrophobic residues in peptides which would be otherwise problematic in aquatic cytosol. Also simple diffusion of peptides would be too ineffective.
== First published posthumously == De Profundis (written 1895–97, in Reading Gaol). Expurgated edition published 1905; suppressed portions 1913, expanded version in The Letters of Oscar Wilde (1962). The Rise of Historical Criticism (written while at college). First published in 1905 (Sherwood Press, Hartford, CT), privately printed. Reprinted in Miscellanies, the last volume of the First Collected Edition (1908). The First Collected Edition (Methuen & Co., 14 volumes) appeared in 1908 and contained many previously unpublished works. The Second Collected Edition (Methuen & Co., 12 volumes) appeared in installments between 1909–11 and contained several other unpublished works. The Letters of Oscar Wilde (written 1868–1900). Published in 1962. Republished as The Complete Letters of Oscar Wilde (2000), with letters discovered since 1962 and new annotations by Merlin Holland. The Women of Homer (written 1876, while at college). First published in Oscar Wilde: The Women of Homer (2008) by the Oscar Wilde Society.
=== Death of Asa Gilbert Eddy === Eddy's husband, Asa Gilbert Eddy, died of heart disease on June 4, 1882, shortly after the move to Boston. She invited the Boston Globe to her home on the day of his death to allege that he had been killed by malicious animal magnetism, courtesy of "certain parties here in Boston, who had sworn to injure them." The Globe wrote:
Sources: en.wikipedia.org
Dry powder is normally held at -20 °C or lower, away from light and moisture. Sealed vials can also be kept at 2-8 °C for shorter intervals. Warming to room temperature before opening prevents condensation.
In solution, hydrolysis of peptide bonds and oxidation of the methionine residue are the principal concerns. Oxidation converts methionine to its sulfoxide form, shifting the mass by sixteen daltons. Both processes are slowed by cold storage and by avoiding alkaline conditions.
A certificate documents what the supplier measured on a specific lot, not how a laboratory will use the material. Independent verification of identity and purity is common practice. Acceptance criteria should be defined before a batch is ordered.
It is a synthetic seven-amino-acid peptide built from the ACTH(4-7) sequence plus a Pro-Gly-Pro tail. It belongs to the family of short ACTH fragments studied for nervous-system effects. Its backbone contains only standard amino acids.