The short version of Certificate of analysis fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2025-08-30 and is reviewed periodically as new material appears.
Once dissolved, the peptide is considerably less stable than the solid. Aqueous solutions are usually prepared at neutral to slightly acidic pH, filtered, and divided into single-use aliquots before freezing. Repeated freeze-thaw cycles are a common cause of avoidable loss and are best prevented by never refreezing a thawed aliquot. Adsorption to plastic and glass surfaces can lower the measured concentration of dilute solutions, particularly below roughly 0.1 mg/mL. Buffer choice, salt content, and container material all influence how much peptide remains detectable after storage.
Identity and purity are established with standard peptide methods. Reversed-phase HPLC with ultraviolet detection near 214 nm resolves the parent peak from deletion and truncation byproducts, and reports typically quote a main-peak percentage. Mass spectrometry by electrospray or MALDI-TOF confirms the expected molecular mass, while amino acid analysis or peptide mapping can verify composition when the sequence itself is in question. A certificate of analysis that pairs a chromatogram with a mass spectrum is more informative than a purity figure alone. Counter-ion content and residual solvents are separate specifications and are frequently omitted.
Dissolution is normally performed in water, phosphate-buffered saline, or normal saline, since the peptide is freely soluble in aqueous media and is rarely handled with strong organic solvents. Solution pH should be kept near neutral, because extreme acidity or alkalinity accelerates backbone hydrolysis and encourages oxidation of the methionine side chain. Once dissolved, the material is less stable than the dry powder and is commonly divided into single-use portions and frozen. Buffers containing primary amines, such as Tris, are often avoided because of possible side reactions.
Purity assessment relies mainly on reversed-phase high-performance liquid chromatography, which separates the target heptapeptide from truncated sequences, deletion analogues, and oxidised forms. Mass spectrometry, usually coupled to liquid chromatography, confirms identity through the expected molecular ion and reveals modifications such as methionine sulfoxide formation. Amino acid analysis can verify composition, and tandem mass spectrometry supports sequence confirmation. Ultraviolet detection near 254 to 280 nanometres is convenient because the phenylalanine and histidine residues absorb in that region. Nuclear magnetic resonance is rarely used for routine release testing.
| Property | Value | Notes |
|---|---|---|
| Solid storage temperature | -20 °C or below | Desiccated and protected from light |
| Solution storage temperature | -80 °C as single-use aliquots | Avoid repeated freeze-thaw cycles |
| Purity assessment method | RP-HPLC, around 214 nm | Reported as main-peak area percent |
| Identity confirmation method | ESI-MS or MALDI-TOF | Measured mass compared with calculated mass |
| Common synonyms | ACTH(4-10) analog; Met-Glu-His-Phe-Pro-Gly-Pro | Also written as Semaxum in some sources |
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.
Identity and purity are commonly assessed by reversed-phase high-performance liquid chromatography, with ultraviolet detection near 214 nanometers for the peptide backbone. Mass spectrometry, either electrospray or matrix-assisted laser desorption, confirms molecular mass and detects truncation or modification products. Amino acid analysis can verify composition. Because the sequence contains no strongly absorbing aromatic residue apart from phenylalanine, detection wavelengths are chosen carefully. Purity values above 95 percent are typical for research-grade material.
Material sold for laboratory use varies widely in stated purity and documentation. A certificate of analysis should list the analytical method, the column and detector used, and the observed purity value. Independent verification by an outside laboratory is the practical way to confirm identity when documentation is absent or internally inconsistent. Regulatory status differs by country, and a product legal in one jurisdiction may be unapproved or controlled in another.
Identity and purity of semax are established with reversed-phase high-performance liquid chromatography coupled to ultraviolet detection, usually at 214 nanometres. Mass spectrometry, most often electrospray ionisation in positive mode, confirms the molecular mass and reveals truncated sequences. Amino acid analysis and peptide mapping after enzymatic digestion provide additional structural confirmation. Laboratories typically report purity as the percentage area of the main peak, a figure that does not capture isomeric or oxidised variants unless the method resolves them.
The peptide is prone to several degradation pathways. Oxidation of the methionine residue produces a sulfoxide that elutes close to the parent peak in many chromatographic systems. Hydrolysis of peptide bonds and deamidation of susceptible residues in related sequences also reduce purity over time. Lyophilised material kept dry at minus twenty degrees Celsius and shielded from light is the most stable form commonly described in laboratory practice.
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。
纯度评估以反相高效液相色谱为主，通过主峰面积百分比给出粗略结果，再配合电喷雾质谱核对分子量。氨基酸分析可验证组成比例，手性色谱或毛细管电泳用于检查残基构型。常见杂质包括缺失序列的短肽、氧化产物与二聚体。由于多数市售品不附带完整检验报告，独立第三方检测常被用来核实标称值。
=== Repair of Oxidative damage === Secondary defenses include DNA-repair systems, proteolytic and lipolytic enzymes. DNA repair enzymes include endonuclease IV, induced by oxidative stress, and exonuclease III, induced in the stationary phase and in starving cells. These enzymes act on duplex DNA and clean up DNA 3' terminal ends. Prokaryotic cells contain catalysts that modify the primary structure of proteins frequently by reducing disulfide bonds. This occurs in the following steps: (i) thioredoxin reductase transfers electrons from NADPH to thioredoxin via a flavin carrier (ii) glutaredoxin is also able to reduce disulfide bonds, but using GSH as an electron donor (iii) protein disulfide isomerase facilitates disulfide exchange reactions with large inactive protein substrates, besides having chaperone activity Oxidation of surface exposed methionine residues surrounding the entrance to the active site could function as a “last-chance” antioxidant defense system for proteins.
== Personal history == Huggins was born in 1897 to Amos Williamson Huggins and Mary Abigail Hackley. He had at least two sisters, Dorothea Harriet Huggins (born September 22, 1894) and Mary Abigail Huggins (born October 2, 1904). He earned his Ph.D. in 1922 under Charles Walter Porter (known as Walter Porter) in the Chemistry Laboratory of the University of California, Berkeley. In 1941 he was elected a Fellow of the American Physical Society. He was employed as a chemist by Eastman Kodak Research Laboratories.
== Society and culture == Vaginal mesh kits were introduced to the U.S. market in 2004 through the U.S. Food and Drug Administration (FDA) pathway that did not require companies to demonstrate both safety and efficacy of the product if they were able to demonstrate that their product was similar to previous products already in the market. However, there was concern over reports of increased rates of postoperative complications over the next several years. That, in addition to the lack of available data that transvaginal mesh products were superior to other forms of surgical intervention and the expedited process which the vaginal mesh kits were introduced to the market, the FDA released a Safety Communication in 2011 that described serious complications associated with transvaginal mesh as "not rare". In 2019, the FDA ordered manufacturers to halt sales of transvaginal mesh intended for repair of pelvic organ prolapse. This does not include surgical mesh used during sacrocolpopexy, sacrohysteropexy, or transurethral sling procedures. Since 2008, a number of class action lawsuits have been filed and settled against several manufacturers of transvaginal mesh after people reported complications following surgery.
Sources: en.wikipedia.org
== Other organisms == Given that DNA and RNA polymerases both carry out template-dependent nucleotide polymerization, it might be expected that the two types of enzymes would be structurally related. However, x-ray crystallographic studies of both types of enzymes reveal that, other than containing a critical Mg2+ ion at the catalytic site, they are virtually unrelated to each other; indeed template-dependent nucleotide polymerizing enzymes seem to have arisen independently twice during the early evolution of cells. One lineage led to the modern DNA polymerases and reverse transcriptases, as well as to a few single-subunit RNA polymerases (ssRNAP) from phages and organelles. The other multi-subunit RNAP lineage formed all of the modern cellular RNA polymerases.
Since 2019, Schleip has been a professor of conservative and rehabilitative orthopaedics in the Department of Sport and Health Sciences at the Technical University of Munich, and a faculty member at the Diploma University of Applied Sciences. In 2023, he was appointed as a professor of health and psychology at the Diploma University of Applied Sciences.
It is capable of assuming more than one conformation. At least one of the conformations creates a channel through the membrane that is permeable to specific types of ions. The transition between conformations is influenced by the membrane potential. Thus, a voltage-gated ion channel tends to be open for some values of the membrane potential, and closed for others. In most cases, however, the relationship between membrane potential and channel state is probabilistic and involves a time delay. Ion channels switch between conformations at unpredictable times: The membrane potential determines the rate of transitions and the probability per unit time of each type of transition.
=== Second and third nucleotide recognition === The second and third position nucleotides are recognized by YxxCxxxF and GTS sites. This process is very important because this gives eRF1 the ability to discriminate the stop codon from a uracil starting sense codons that codes for an amino acid. For example the cysteine amino acid is coded by the codon UGU. The first step in discriminating stop from sense codons is to distinguish purines from pyrimidines, since all stop codons have purine nucleotides in the +2 and +3 position. Two highly conserved amino acid residues Glu55 and Tyr125 (located in the YxxCxxxF motif) work in tandem to hydrogen bond with the N6 nitrogen atom on the adenosine/guanine nucleotide. This interaction excludes the possibility of pyrimidines in the +2 and +3 position. Further discrimination of the purines in the +2 and +3 position is need since UGG is a sense codon for tryptophan. In the case of UGG, the Glu55 residue is repelled from the strong negative charge from the two guanine nucleotides. Since no extensive hydrogen bonding occurred, the codon is not recognized as a stop codon. A very important residue in eRF1 is the Cys127 in the YxxCxxxF motif, which forms 2 hydrogen bonds with a Watson and Crick's edge located on the mRNA. The hydrogen bonding allows further stability of the eRF1-stop codon complex in multiple orientations and allows stacking/hydrogen bonding of the +2 and +3 position of the stop codon. The strength and number of the stacks on the second and third position allows eRF1 to discriminate stop codons from sense codons.
Sources: en.wikipedia.org
Each freeze-thaw cycle can degrade a fraction of the peptide and promote aggregation. Dividing a stock solution into single-use volumes removes repeated cycling as a variable. It also limits the time a thawed solution spends at room temperature.
A high main-peak percentage says little about identity, counter-ion content, or residual solvents. It also does not distinguish an isomer or a closely eluting analog. Mass confirmation and the accompanying documentation cover those gaps.
Salt form changes mass, solubility, and hygroscopicity, and acetate and trifluoroacetate salts behave differently in solution. Storage guidance still centers on -20 °C for powder and lower temperatures for solutions. The certificate should state which salt is present.
Dry powder is usually kept at about -20 degrees Celsius for long-term storage and at 2 to 8 degrees Celsius for short working periods. Containers should stay sealed and protected from light and moisture to limit degradation.