deamidation raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
This page was last updated on 2026-01-08 and is reviewed periodically as new material appears.
Lyophilization removes water under vacuum from a frozen solution, leaving a porous cake or powder. Formulation excipients such as sugars or polyols can stabilize structure during freezing and drying and can raise the glass transition temperature. Residual moisture in the final product remains a critical variable because even small amounts can support hydrolysis over time. Storage recommendations often specify desiccation, darkness, and low temperature, though exact conditions depend on the peptide and its intended use. Stability studies measure changes under defined conditions rather than predicting absolute shelf life.
Peptides are short chains of amino acids linked by amide bonds. Their stability depends on sequence, length, and the chemical environment. Common degradation routes include hydrolysis of the peptide backbone, oxidation of methionine or cysteine residues, deamidation of asparagine or glutamine, and aggregation through hydrophobic or electrostatic interactions. These processes can alter mass, charge, or biological activity, so storage conditions aim to slow them. The relative importance of each route varies widely among peptides.
Temperature is a primary factor in peptide storage. Lower temperatures reduce molecular motion and slow degradation reactions, but freezing can concentrate solutes and promote aggregation. Lyophilized powders are commonly held at -20°C, whereas solutions are often kept at -80°C. Repeated freeze-thaw cycles are harmful because ice crystal formation and pH shifts can damage the peptide. The glass transition temperature of a lyophilized cake influences its stability; below this temperature, molecular mobility is restricted. For solutions, the choice between -20°C and -80°C depends on the peptide's sensitivity and the intended storage duration.
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.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Typical for lyophilized or dry peptide material |
| Solubility class | Often freely soluble in water | Depends on sequence and counterion |
| Typical dry storage temperature | -20 °C or lower | Cooler conditions generally slow degradation |
| Common degradation route | Hydrolysis, oxidation, deamidation | Relative importance varies by sequence |
| Typical analytical method | RP-HPLC and LC-MS | Used to assess purity and mass |
Co-administration with strong inhibitors of the liver enzyme CYP3A4 (e.g. ketoconazole, ritonavir, clarithromycin, grapefruit juice) may increase pazopanib serum levels as it is a CYP3A4 substrate. CYP3A4 inducers (e.g. rifampin, carbamazepine) decrease pazopanib serum levels. It is a p-glycoprotein (PGP) substrate and hence PGP inhibitors such as quinidine may interact with pazopanib. Pazopanib is not a substrate for either of the liver enzymes OATP1B1 and OATP1B3. Pazopanib has inhibitory potency towards OATP1B1 but not for OATP1B3.
Mitragotri has invented many novel drug delivery technologies, especially in the fields of transdermal, oral and targeted systems. He invented techniques to deliver drugs transdermally using low-frequency ultrasound, pulsed microjet injector, high throughput skin experimentation, skin penetrating peptides and ionic liquids. He also invented intestinal patches and ionic liquids for oral delivery of proteins. Mitragotri also pioneered nanoparticle-enabled cell therapies which use drug-loaded nanoparticles that hitch a ride on red blood cells, monocytes and other circulatory cells for tissue-specific delivery. Mitragotri's technologies are used to develop next generation therapies against diabetes, cancer, psoriasis, hemorrhage, trauma and infections. Mitragotri has published over 400 research publications and is an inventor on over 300 patents/applications. His publications are cited over 81000 times with an h-index of 140. Mitragotri is a member of the US National Academy of Medicine and the US National Academy of Inventors. He is also a member of the US National Academy of Engineering since 2015 for the development, clinical translation, and commercialization of transdermal drug delivery systems. He is also an elected member of The World Academy of Science , American Academy of Arts & Sciences and Indian National Academy of Engineering. He is a co-founder of several companies that are developing products based on his inventions. He received his PhD in chemical engineering at MIT and BS in chemical engineering from the Institute of Chemical Technology.
== Peptide hormones and related substances == Certain peptide hormones increase bulk, strength, and oxygen-carrying red blood cells. Erythropoiesis-stimulating agents such as erythropoietin (EPO), darbepoetin (dEPO), hypoxia-inducible factor (HIF) stabilizers, methoxy polyethylene glycol-epoetin beta (CERA) and peginesatide (Hematide); growth hormone (hGH), insulin-like growth factors (IGF-1, etc.), fibroblast growth factors (FGFs), hepatocyte growth factors (HGF), mechano growth factors (MGFs), platelet-derived growth factor (PDGF), vascular endothelial growth factor (VEGF), human chorionic gonadotropin (hcG, banned in men only), somatotrophin (growth hormone), insulins and corticotrophins, corticosteroid mimics, and their releasing factor, are banned. Also banned are any other growth factor affecting muscle, tendon or ligament protein synthesis/degradation, vascularization, energy utilization, regenerative capacity or fiber type switching, and other substances with similar chemical structure and/or biological effects.
Herbie Hancock – electric piano (Rhodes, clavinet), synthesizer/FX Melvin "Wah Wah" Ragin – guitar Ray Parker Jr. – guitar Paul Jackson – electric bass James Levi – drums Kenneth Nash – percussion Bennie Maupin – tenor & soprano saxophones, lyricon
Sources: en.wikipedia.org
Peptides is a monthly peer-reviewed scientific journal covering the biochemistry, neurochemistry, pharmacology, and biological functions of peptides. It was established in 1980 and is published by Elsevier. The editor-in-chief is Karl-Heinz Herzig (University of Oulu).
The percentage of the Portuguese population suffering from moderate or severe food insecurity between 2022 and 2024 was on average 11.9%, which makes Portugal the third-highest country in Southern Europe for this indicator where the average stands at 5.9%. Stakeholders have raised concerns over the effectiveness of food safety policies.
Star anise contains anethole, the same compound that gives anise, an unrelated plant, its flavor. Star anise has come into use in the West as a less expensive substitute for anise in baking, as well as in liquor production, most distinctively in the production of the liqueur Galliano. Star anise enhances the flavor of meat. It is used as a spice in preparation of biryani and masala chai in some parts of the Indian subcontinent. It is widely used in Chinese cuisine, and in Malay and Indonesian cuisines. It is widely grown for commercial use in China, India, and most other countries in Asia. Star anise is an ingredient of the traditional five-spice powder of Chinese cooking. It is also a major ingredient in the making of phở, a Vietnamese noodle soup. It is also used in the French recipe of mulled wine, vin chaud (hot wine). If allowed to steep in coffee, it deepens and enriches the flavor. The pods can be used in this manner multiple times by the potful or cup, as the ease of extraction of the taste components increases with the permeation of hot water.
== Notable users == King Chulalongkorn of Thailand (1853–1910) used the drug for a period after 1893 to relieve what may have been a mix of depression and unspecified illnesses. He was reported by his doctor to have been taking one bottle per day during July 1894 although this was reduced after this time. Montgomery Clift (1920–1966), American actor. André Gide (1869–1951) was given chloral hydrate as a boy for sleep problems by a physician named Lizart. Gide states in his autobiography If It Die... that "all my later weaknesses of will or memory I attribute to him." William James (1842–1910), psychologist and philosopher, used the drug for insomnia and sedation due to chronic neurosis. The Jonestown mass murder-suicides in 1978 involved the communal drinking of Flavor Aid poisoned with diazepam, chloral hydrate, cyanide, and promethazine. Mary Todd Lincoln (1818–1882), wife of American president Abraham Lincoln, became addicted in the years after her husband's death and was committed to an asylum. Marilyn Monroe (1926–1962) died from an overdose of chloral hydrate and pentobarbital (Nembutal). Friedrich Nietzsche (1844–1900) regularly used chloral hydrate in the years leading up to his nervous breakdown, according to Lou Salomé and other associates. Whether the drug contributed to his insanity is a point of controversy. Dante Gabriel Rossetti (1828–1882) became addicted to chloral, with whisky chasers, after the death of his wife Elizabeth Siddal from a laudanum overdose in 1862. He had a mental breakdown in 1872.
Public health laboratories operate as a first line of defense to protect the public against diseases and other health hazards. Day-to-day operations range from testing water and food, checking for toxins in soil, and investigating new strains of infectious diseases, such as COVID-19 or Ebola. Every US state and territory, and the District of Columbia, has a central governmental public health laboratory that performs testing and other laboratory services on behalf of the entire jurisdiction. In addition, some states have local public health laboratories ranging in size from large metropolitan laboratories with over a hundred scientists to small rural laboratories with one or two staff that support local public health.
Sources: en.wikipedia.org
{\displaystyle {\ce {{^{238}_{92}U}+{}_{0}^{1}n->{}_{92}^{239}U->[\beta ^{-}][23.5\ {\ce {min}}]{}_{93}^{239}Np->[\beta ^{-}][2.3\ {\ce {days}}]{}_{94}^{239}Pu}}\left({\ce {->[\alpha ][2.4\cdot 10^{4}\ {\ce {years}}]}}\right){\ce {^{235}_{92}U}}}
=== Obstructive sleep apnea in pregnancy === Sleep apnea can result in intermittent hypoxia and has been increasing in prevalence due in part to the obesity epidemic. The known maternal risk factors for autism diagnosis in her offspring are similar to the risk factors for sleep apnea. For example, advanced maternal age, maternal obesity, maternal type 2 diabetes and maternal hypertension all increase the risk of autism in her offspring. Likewise, these are all known risk factors for sleep apnea. One study found that gestational sleep apnea was associated with low reading test scores in children and that this effect may be mediated by an increased risk of the child having sleep apnea themselves. Another study reported low social development scores in 64% of infants born to mothers with sleep apnea compared to 25% of infants born to controls, suggesting sleep apnea in pregnancy may have an effect on offspring neurodevelopment. There was also an increase in the amount of snoring the mothers with sleep apnea reported in their infants when compared to controls. Children with sleep apnea have "hyperactivity, attention problems, aggressivity, lower social competency, poorer communication, and/or diminished adaptive skills". One study found significant improvements in ADHD-like symptoms, aggression, social problems and thought problems in autistic children who underwent adenotonsillectomy for sleep apnea. Sleep problems in autism have been linked in a study to brain changes, particularly in the hippocampus, though this study does not prove causation.
Following the Russian invasion of Ukraine, many companies, including Burger King, faced growing pressure to halt operations in Russia. In March 2022, Burger King claimed to have suspended all its corporate support, including operations, marketing, supply chain, investments and expansion in Russia in response to the invasion of Ukraine, including support to the more than 800 fully franchised restaurant chains in Russia managed by a local master franchisee. However, the International Consortium of Investigative Journalism revealed that Burger King retained its stake in the Russian franchises through an offshore joint venture with the Russian state-owned VTB Bank and a Ukrainian investment firm linked to corrupt deals with Ukraine's former pro-Russian leader. In October 2023, Tom Curtis, president of Burger King U.S. & Canada, announced a new store design at its annual franchisee convention in Canada, branded "The Sizzle". The company planned to remodel existing Burger King locations with a new interior and exterior look, to tackle slowing business after the 2020 coronavirus pandemic. The overhaul plan included more kiosks, dedicated pickup areas for mobile app orders, food-ordering platforms like Doordash, Uber Eats, and Grubhub, and an improved drive-thru service. In 2023, Burger King remodeled several locations in the United States with the "Sizzle" concept. While the remodel plan was an overhaul to the entire restaurant, Burger King was also investing in a "Refresh" initiative in order to replace equipment and upgrade technologies.
==== Units ==== Due to the variety of natural and synthetic compounds with vitamin E activity, there has historically been many different units that attempt to produce a measure of "vitamin E activity" using a weighted sum. The international unit measurement was used by the United States in 1968–2016. 1 IU is the biological equivalent of about 0.667 mg d (RRR)-alpha-tocopherol (2/3 mg exactly), or of 0.90 mg of dl-alpha-tocopherol (or of 1.0 mg of dl-alpha-tocopherol acetate), corresponding to the then-measured relative potency of stereoisomers. In May 2016, the measurements were revised, such that 1 mg "as alpha-tocopherol" of Vitamin E is 1 mg of d-alpha-tocopherol or 2 mg of dl-alpha-tocopherol. The change was originally started in 2000, when forms of vitamin E other than alpha-tocopherol were dropped from dietary calculations by the IOM. The UL amount disregards any conversion. The EFSA has never used an IU unit, and their measurement only considers RRR-alpha-tocopherol.
Sources: en.wikipedia.org
Peptide degradation can arise from hydrolysis, oxidation, deamidation, and aggregation. The dominant route depends on the peptide sequence and the storage environment. Temperature, moisture, oxygen, light, and pH all influence the rate.
Freezing slows many chemical reactions but does not stop all degradation. Repeated freeze-thaw cycles can promote aggregation or precipitation. Dry powders and solutions may respond differently to freezing.
pH affects the charge state of ionizable groups and can influence deamidation, hydrolysis, and aggregation. A pH that stabilizes one peptide may destabilize another. Buffer components can also participate in degradation or stabilization.
Removing water reduces hydrolytic degradation and limits microbial growth. Lyophilized powders are generally more stable at higher temperatures than aqueous solutions. They also tolerate shipping with less risk of degradation.