The short version of Deamidation fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2025-11-09 and is reviewed periodically as new material appears.
Light exposure can damage aromatic residues and certain labels, so amber vials or opaque containers are often used. pH control matters in solution, as extreme acidity or alkalinity accelerates backbone cleavage; buffers may also introduce ions that affect solubility. Microbial growth is a concern for aqueous preparations that lack preservatives, though many research peptides are handled in sterile or low-bioburden conditions. Container materials can adsorb peptides, particularly hydrophobic or positively charged sequences, reducing recovery. These factors interact, meaning storage decisions balance chemical stability, physical state, and intended use.
Peptides are short chains of amino acids whose physical and chemical stability depends on sequence, length, and conformation. The amide backbone can hydrolyze under acidic or basic conditions, while side chains such as methionine, cysteine, and tryptophan are prone to oxidation. Aggregation may occur when hydrophobic regions associate, especially near surfaces or at high concentration. Because these pathways differ among peptides, no single storage condition applies to all sequences. Stability studies therefore examine each peptide under defined temperature, pH, and humidity ranges.
Temperature is a primary variable because most degradation reactions slow as thermal energy decreases. Lyophilized powders are commonly held at -20 °C for routine work and at -80 °C for longer archival periods, though exact recommendations depend on the peptide. Solutions are less stable than dry powders in many cases, and repeated freeze-thaw cycles can promote aggregation or precipitation. Inert atmospheres, such as argon or nitrogen, can limit oxidation for oxygen-sensitive sequences. Desiccants reduce water activity, which lowers hydrolysis rates during storage.
Reconstitution is often performed with sterile water, buffer, or a water-miscible organic solvent, depending on solubility. The solvent should be added gently along the vial wall, and the solution mixed by gentle swirling rather than vigorous vortexing, which can cause foaming and surface denaturation. Some sequences require a small amount of base or acid to dissolve, followed by pH adjustment. Preparing a concentrated stock solution can simplify later dilution, but the stock itself may have limited stability. Records of solvent, concentration, and date support reproducibility.
After reconstitution, dividing the solution into single-use aliquots limits multiple warming and cooling events and reduces contamination risk. Low-binding polypropylene tubes are often preferred because peptides can adsorb to glass or untreated plastic surfaces. Filling headspace with nitrogen or argon can slow oxidation, and amber or foil-wrapped containers reduce photodegradation. Each aliquot should be labeled with peptide identity, concentration, date, and storage conditions. Frozen aliquots should be thawed quickly and kept on ice until use.
When a peptide arrives, the vial should be inspected for damage, and its label, lot number, and accompanying analytical data should be recorded. Cold vials should equilibrate to room temperature before opening to prevent condensation on the powder. Moisture uptake can reduce stability and complicate accurate weighing or reconstitution. Inventory systems that track date, quantity, and storage location help prevent unnecessary temperature cycling. Personnel should follow institutional or manufacturer instructions for any specific peptide.
| Property | Value | Notes |
|---|---|---|
| Appearance (lyophilized powder) | White to off-white powder | Color varies with sequence, counterion, and residual solvent. |
| Solubility | Aqueous or organic depending on sequence | Hydrophobic peptides may require organic co-solvents. |
| Typical storage temperature (dry) | -20 °C or lower | -80 °C is used for long-term archival storage. |
| Common analytical method | Reversed-phase HPLC | Purity and identity are assessed by retention time and peak area. |
| Common synonyms | Peptide, oligopeptide, polypeptide | Usage varies with chain length and context. |
Shipping and short-term transfer require attention to temperature control and physical stability. Frozen solutions are commonly sent on dry ice, while lyophilized powders may travel with gel packs or insulated packaging. Thawing should be done slowly on ice or in a refrigerator, not by vigorous heating, and the solution should be mixed gently before use. Temperature loggers can document excursions during transit, but their presence does not prove that a peptide remained stable. Analytical checks such as chromatography or mass spectrometry can verify identity and purity after storage or shipping.
Reconstitution begins with selecting a solvent that dissolves the peptide without causing degradation. Water or aqueous buffer is suitable for many hydrophilic sequences, while hydrophobic peptides may require a small amount of organic solvent such as acetonitrile or dimethyl sulfoxide before dilution. The solvent is added to the vial rather than the powder being scraped out, and the mixture is swirled or inverted gently to avoid foaming. Complete dissolution should be confirmed visually, and insoluble material may indicate aggregation or impurities. Because solvent tolerance varies, published solubility information or a small test dissolution can guide handling.
Moisture, oxygen, and light also affect peptide integrity. Lyophilized powders absorb water from the air, which can enable hydrolysis and conformational changes. Oxygen promotes oxidation of sensitive residues, so storage under inert gas or in sealed vials is common. Light exposure can cause photodegradation, particularly for peptides containing aromatic amino acids. Buffer choice and pH influence charge state and solubility; extremes of pH accelerate deamidation and hydrolysis. Adding stabilizers such as sugars or polyols can protect the peptide during freezing and drying. Optimal conditions are determined empirically for each peptide.
Peptides are short chains of amino acids that can undergo both chemical and physical degradation. Chemical pathways include hydrolysis of peptide bonds, oxidation of methionine or cysteine residues, deamidation of asparagine or glutamine, and isomerization of aspartate. Physical instability leads to aggregation, precipitation, or adsorption to surfaces. The rate of these processes depends on the peptide sequence, the formulation, and the storage environment. Because each peptide has a unique composition, no single storage condition applies to all peptides. Stability studies are therefore conducted to define suitable conditions for each specific molecule.
In aqueous solution, peptides are vulnerable to hydrolysis, oxidation, deamidation, and aggregation, with rates influenced by pH, temperature, buffer composition, and ionic strength. Acidic or neutral pH ranges often slow deamidation, while extreme pH can accelerate peptide bond cleavage. Dissolved oxygen and redox-active metal ions contribute to oxidation of methionine, cysteine, and tryptophan residues. Aggregation may be driven by hydrophobic interactions or by interfaces such as air-liquid and container surfaces. Because these pathways interact, solution storage usually requires tighter control than storage of dried material.
Temperature is the most common controlled variable, but its effect is not linear. Lower temperatures reduce most chemical reaction rates, yet freezing can concentrate solutes and create pH shifts in the remaining liquid phase. Repeated freeze-thaw cycles can denature or aggregate some peptides, especially those with hydrophobic segments. For lyophilized powders, desiccation and protection from moisture are often more important than deep freezing. For solutions, the choice between refrigeration and freezing depends on peptide concentration, buffer components, and the intended duration of storage.
Peptides are short chains of amino acids whose physical and chemical stability depends on sequence, length, conformation, and the surrounding matrix. In the solid state, lyophilized powders are generally more stable than solutions because low water activity slows hydrolysis and oxidation. Residual moisture, oxygen, trace metals, and light can still promote degradation over time. Storage recommendations therefore balance temperature, humidity, and container integrity rather than relying on a single condition. The optimal condition for a given peptide is often determined empirically because no universal rule covers every sequence.
Light, oxygen, and pH influence peptide integrity through specific side-chain reactions. Methionine and cysteine residues are susceptible to oxidation, and tryptophan can degrade under strong light. Inert gas overlays and amber glass or opaque containers reduce these risks. pH affects charge, solubility, and the rate of deamidation or aggregation; a value that minimizes one pathway may increase another. The optimal pH and buffer for a given peptide are often determined experimentally, and open questions remain about predicting stability from sequence alone.
Peptides are short chains of amino acids linked by amide bonds, and their storage stability depends on sequence, length, and three-dimensional structure. Chemical degradation can occur through hydrolysis, oxidation, deamidation, and aggregation, while physical changes such as precipitation or surface adsorption reduce recovery. Storage conditions are chosen to slow these processes without altering the peptide itself. Because peptides vary widely, no single condition suits every sequence, so laboratories often establish stability empirically for each batch.
Hitler, aiming to use the crisis as a pretext for war, now demanded not only the annexation of the Sudetenland but also the immediate military occupation of Bohemia, Moravia and Slovakia, thus giving the Czechoslovak army no time to adapt its defence measures to the new borders. Hitler, in a speech at the Sportpalast in Berlin, claimed that the Sudetenland was "the last territorial demand I have to make in Europe" and gave Czechoslovakia a deadline of 28 September 1938 at 2:00 p.m. to cede the Sudetenland to Germany or face war. To achieve a solution, the Italian dictator, Benito Mussolini, suggested a conference of the major powers in Munich, and on 29 September, Hitler, Daladier and Chamberlain met and agreed to Mussolini's proposal (actually prepared by Hermann Göring) and signed the Munich Agreement. They accepted the immediate occupation of the Sudetenland. The Czechoslovak government, though not party to the talks, submitted to compulsion and promised to abide by the agreement on 30 September. The Sudetenland was assigned to Germany between 1 and 10 October 1938. The Czech part of Czechoslovakia was subsequently invaded by Germany in March 1939, with a portion being annexed and the remainder turned into the Protectorate of Bohemia and Moravia. The Slovak part declared its independence from Czechoslovakia and became the Slovak Republic (Slovak State), a satellite state allied to Germany.
=== Safety === Tests of common teas have detected residues of banned toxic pesticides. Additionally, tests have indicated contamination of heavy metals and toxic elements in some brewed teas, some having a proportional relationship between the concentration of contaminants and steeping time. Another study indicated that heavy metals in commercial teas are tightly bound to tea leaves, with a minor amount leeching off into the water while brewing.
== Career == After graduating from Ohio State University in 1938, Minnich wrote to Carl Moore to ask for a job and he offered her a position as a research technician helping start a Hematology department at Washington University. She remained at Washington University for her entire career. She was promoted to a research associate in 1954, research assistant professor in 1958, research associate professor in 1963, and full professor of Medicine in 1974 (the first person without a doctorate degree to reach this rank at Washington University). She became professor emeritus in 1978 and retired in 1984. She also worked at Barnes Hospital in St. Louis from 1975 to the mid-1980s as assistant and then associate director of Hematology. She was regarded as an excellent teacher and, in addition to her official teaching responsibilities, she gave informal "night courses" to pathologists, lab technicians, and others. She created a series of audiovisual teaching materials describing the morphology of blood and bone marrow that were published by the American Society of Clinical Pathologists in the early 1980s as a 10-part course in morphologic hematology.
Part II of his poem "Howl" was inspired by a peyote vision that he had in San Francisco. Aldous Huxley described his experience with mescaline in the essay "The Doors of Perception" (1954). Ken Kesey took peyote prior to writing One Flew Over the Cuckoo's Nest. Stanisław Ignacy Witkiewicz, Polish writer, artist and philosopher, experimented with mescaline and described his experience in a 1932 book Nikotyna Alkohol Kokaina Peyotl Morfina Eter. Jim Carroll in The Basketball Diaries described using peyote that a friend smuggled from Mexico. Quanah Parker, appointed by the federal government as principal chief of the entire Comanche Nation, advocated the syncretic Native American Church alternative, and fought for the legal use of peyote in the movement's religious practices. Hunter S. Thompson wrote an extremely detailed account of his first use of mescaline in "First Visit with Mescalito", and it appeared in his book Songs of the Doomed, as well as featuring heavily in his novel Fear and Loathing in Las Vegas. Alexander Shulgin, the prolific psychedelic chemist, said that he was first inspired to explore psychedelic compounds by a mescaline experience in 1960. In 1974, Shulgin synthesized 2C-B, a psychedelic phenylethylamine derivative, structurally similar to mescaline, and one of Shulgin's self-rated most important phenethylamine compounds together with mescaline, 2C-E, 2C-T-7, and 2C-T-2. Bryan Wynter produced Mars Ascends after trying the substance for the first time. George Carlin mentioned mescaline use during his youth while being interviewed in 2008.
Sources: en.wikipedia.org
Bromazolam (XLI-268) is a triazolobenzodiazepine (TBZD) which was first synthesised in 1976, but was never marketed. It has subsequently been sold as a designer drug, first being definitively identified by the EMCDDA in Sweden in 2016. It is the bromo instead of chloro analogue of alprazolam and has similar sedative and anxiolytic effects to it and other benzodiazepines. Bromazolam is a non subtype selective agonist at the benzodiazepine site of GABAA receptors, with a binding affinity of 2.81 nM at the α1 subtype, 0.69 nM at α2 and 0.62 nM at α5. The "common" dosage range for users of bromazolam was reported to be 1–2 mg, suggesting its potency is similar to alprazolam.
== Awards and recognition == Eke has received several awards for his contributions to medicine and public health. These include the Donald F. Richardson Memorial Research Award from ACOG, the Kenneth Warren Prize from the Cochrane Collaboration, and the Young Physician-Scientist Award from the American Society for Clinical Investigation (ASCI). He is a member of both the Alpha Omega Alpha Honor Medical Society and the Delta Omega Honorary Society in Public Health. In 2024, he was recognized by the NIH Common Fund as a recipient of the Director's Pioneer Award, one of the agency's most competitive and prestigious awards for high-risk, high-reward research. In 2025, Eke was recognized as one of the top 1% of Gynecologic Surgery Research All-Stars. Eke's research and expert opinion have been featured in a range of media outlets, including STAT News, MedPage Today, Medscape, HuffPost, and Runner's World.
== Other uses == C4, a variation of Command and control, meaning "Command, Control, Communications and Computers" C4, the monogram of Christian IV of Denmark, used in the city arms of Kristianstad, Sweden since 1622 C4 Extreme, a sports nutrition supplement product line by Cellucor, which includes C4 energy drinks
In 1896, Viennese dermatologist Leopold Freund (1868-1943) used X-rays to treat patients for the first time. He successfully irradiated the hairy nevus of a young girl. In 1897, Hermann Gocht (1869–1931) published the treatment of trigeminal neuralgia with X-rays, and Alexei Petrovich Sokolov (1854-1928) wrote about radiotherapy for arthritis in the oldest radiology journal, Advances in the field of X-rays (RöFo). In 1922, X-rays were recommended as safe for many diseases and for diagnostic purposes. Radiation protection was limited to recommending doses that would not cause erythema (reddening of the skin). For example, X-rays were promoted as an alternative to tonsillectomy. It was also boasted that in 80% of cases of diphtheria carriers, Corynebacterium diphtheriae was no longer detectable within two to four days. In the 1930s, Günther von Pannewitz (1900–1966), a radiologist from Freiburg, Germany, perfected what he called X-ray stimulation radiation for degenerative diseases. Low-dose radiation reduces the inflammatory response of tissues. Until about 1960, children with diseases such as ankylosing spondylitis or favus (head fungus) were irradiated, which was effective but led to increased cancer rates among patients decades later. In 1926, the American pathologist James Ewing (1866-1943) was the first to observe bone changes as a result of radiotherapy, which he described as radiation osteitis (now Osteoradionecrosis). In 1983, Robert E. Marx stated that osteoradionecrosis is radiation-induced aseptic bone necrosis.
== Work == During his career, Roderich Süssmuth worked in the field of peptide synthesis, addressing current research questions from both a chemical perspective (natural product synthesis) and a biological perspective, particularly with regard to new classes of active compounds with activity against fungi, bacteria, and viruses. Compounds derived from plant-pathogenic bacteria such as Xanthomonas albilineans play an important role, including albicidin, which is an inhibitor of plant gyrase and also a highly potent antibacterial agent. He elucidated the structure of the antibacterial compound albicidin, investigated its biosynthesis, developed the total synthesis of the peptide, and studied a range of bacterial resistance factors, mostly from plant-associated bacteria. Another example is the recent elucidation of a lipopeptide from Burkholderia sp., which exhibits pronounced activity against plant-pathogenic fungi. Another area of research involves fungal toxins of the death cap mushroom, phalloidin and amanitin, for which total syntheses were developed and, with the ansamer concept, a novel non-classical atropisomerism was described.
Sources: en.wikipedia.org
Panic disorder with or without agoraphobia. Body dysmorphic disorder Repetitive self-injurious/self-harming behaviours in those with intellectual disability specifically. The subtype of systemised paranoia characterised by somatic phenomena. Compulsive nail-biting (onychophagia). Cataplexy associated with narcolepsy. This is a TGA and MHRA-labeled indication for clomipramine. Self-bloodletting Premature ejaculation, where it may be more effective than paroxetine Depersonalization-derealization disorder Chronic pain with or without organic disease, particularly headache of the tension type. Developmental stuttering Sleep paralysis, with or without narcolepsy Enuresis (involuntary urinating in sleep) in children. The effect may not be sustained following treatment, and alarm therapy may be more effective in both the short-term and the long-term. Combining a tricyclic (such as clomipramine) with anticholinergic medication may be more effective for treating enuresis than the tricyclic alone. Trichotillomania In combination with lithium and tryptophan for severe, particularly treatment-resistant depression. This combination, in a similar vein, has also been used for clomipramine-resistant obsessive-compulsive disorder. When electro-convulsive therapy is performed alongside this treatment-regime (as may be the case in severe depression and accompanied with thyroxine,) however, great care must be taken with lithium. The overall risk of seizures may have to be weighted against the refractory severity of the current illness and necessity of the amalgamation of treatment(s).
== Opioids and receptors == Endomorphins belong to the opioid class of neuropeptides (protein neurotransmitters). Opioids are ligands that bind to opioid receptors and exist both as endogenous substances that are generated within the organism and as synthetic molecules. Endogenous opioids include endorphins, enkephalins, dynorphins, and endomorphins. Transcription and translation of opioid-encoding genes results in the formation of pre-propeptide opioid precursors, which are modified in the endoplasmic reticulum to become propeptide opioid precursors, transferred to the golgi apparatus, and further modified into the opioid product. The exact pre-propeptide precursors of endomorphins have not been identified. Because the precursors have never been identified and the mechanisms by which the endomorphins are produced have never been clarified, the status of endomorphins as endogenous opioid ligands has to be considered tentative. Opioid receptors belong to the G protein-coupled receptor family and include μ, κ, δ, and nociceptinorphanin-FQ receptors. While activation of opioid receptors initiates a diverse array of responses, opioids typically serve as depressants, and are widely used and developed as analgesics. Additionally, opioid malfunction has been linked to schizophrenia and autism. Endomorphins demonstrate high selectivity and affinity for the μ-opioid receptor, which functions in pain relief and intoxication.
A graphene-based implant on the surface of mouse brains, in combination with a two-photon microscope, is shown to capture high-resolution information on neural activity at depths of 250 micrometers. A review of genetic data from 21 studies with nearly one million participants finds more than 50 new genetic loci and 205 novel genes associated with depression, opening potential targets for drugs to treat depression. The Upano Valley sites are reported as the oldest Amazonian cities built over 2500 years ago, with a unique "garden urbanism" city design. A study presents results of a Riyadh-based trial of eight urban heat mitigation scenarios, finding large cooling effects with combinations that include reflective rooftop materials, irrigated greenery, and retrofitting. 12 January Global warming: 2023 is confirmed as the hottest year on record by several science agencies. NASA reports a figure of 1.4 degrees Celsius above the late 19th century average, when modern record-keeping began. NOAA reports a figure of 1.35 degrees Celsius. Berkeley Earth reports a figure of 1.54 degrees Celsius. An AI-based study shows for the first time that fingerprints from different fingers of the same person share strong detectable similarities. 13 January – NASA fully opens the recovered container with samples from the Bennu asteroid, after three months of failed attempts. 16 January – The first successful cloning of a rhesus monkey is reported by scientists in China.
== Biological role and toxicity == Dichloroacetylene causes severe neurological disorders, among other problems. Main route of human exposure to dichloroacetylene has been the breakdown of trichloroethylene in presence of alkali hydroxides, historically during trichloroethylene anaesthesia when soda lime was used. Humans exposed to dichloroacetylene showed symptoms such as nausea, vomiting, loss of appetite, headache, facial nervous and muscular issues, and formation of herpes-like lesions on the face. Some people reported itching around the eyes and pain around the jaw. It affects the trigeminal nerve in particular and over-exposure could be fatal. Studies on male rats and rabbits have shown that inhalation of dichloroacetylene can cause tubular necrosis, focal necrosis, and other nephrotoxic effects. Additionally, the rabbits that were given dichloroacetylene experienced hepatotoxic and neuropathological effects. Inhalation of dichloroacetylene also causes benign tumors of the livers and kidneys of rats. The chemical also caused increased instances of lymphomas. It also causes weight loss in animals. 3.5% of a dose of dichloroacetylene remains in the corpses of male Wistar rats. The LC50s of mice exposed to dichloroacetylene are 124 parts per million for a 1-hour exposure by inhalation and 19 parts per million for a 6-hour exposure by inhalation. The chemical is ingested primarily through glutathione-dependent systems. Glutathione also reacts with it. Hepatic and renal glutathione S-transferases serve as catalysts to this reaction.
=== Etymology === Androgens were discovered in the 1930s and were characterized as having effects described as androgenic (i.e., virilizing) and anabolic (e.g., myotrophic, renotrophic). The term anabolic steroid can be dated as far back as at least the mid-1940s, when it was used to describe the at-the-time hypothetical concept of a testosterone-derived steroid with anabolic effects but with minimal or no androgenic effects. This concept was formulated based on the observation that steroids had ratios of renotrophic to androgenic potency that differed significantly, which suggested that anabolic and androgenic effects might be dissociable. In 1953, a testosterone-derived steroid known as norethandrolone (17α-ethyl-19-nortestosterone) was synthesized at G. D. Searle & Company and was studied as a progestin, but was not marketed. Subsequently, in 1955, it was re-examined for testosterone-like activity in animals and was found to have similar anabolic activity to testosterone, but only one-sixteenth of its androgenic potency. It was the first steroid with a marked and favorable separation of anabolic and androgenic effect to be discovered, and has accordingly been described as the "first anabolic steroid". Norethandrolone was introduced for medical use in 1956, and was quickly followed by numerous similar steroids, for instance nandrolone phenylpropionate in 1959 and stanozolol in 1962. With these developments, anabolic steroid became the preferred term to refer to such steroids (over "androgen"), and entered widespread use.
Sources: en.wikipedia.org
Freezing slows hydrolysis and oxidation by reducing molecular motion and available water. Lyophilized powders contain little moisture, so they can remain stable for extended periods when kept cold and dry. The exact temperature depends on peptide sequence and expected storage duration.
Solutions generally degrade faster because water participates in hydrolysis and enables aggregation or microbial growth. Buffer composition, pH, and concentration influence the rate. For this reason, many procedures prepare solutions shortly before use and avoid long-term liquid storage.
Ice crystal formation and concentrated solutes can stress peptide molecules and promote aggregation. Repeated cycling also exposes the sample to temperature fluctuations that may accelerate degradation. Aliquoting before freezing reduces the number of cycles a single container experiences.
Dividing a stock into single-use portions usually reduces multiple thawing and refreezing events and lowers contamination risk. It also allows a needed amount to be removed without warming the entire supply.