The short version of deamidation fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-01-05. Anything still debated is marked as such rather than presented as settled.
Reversed-phase high-performance liquid chromatography is widely used to assess purity and to separate the parent peptide from related substances. Mass spectrometry confirms identity and can resolve modifications that differ by a few daltons. Size-exclusion chromatography detects dimers and higher aggregates, which are relevant to both stability and immunogenicity questions. Peptide mapping with enzymatic digestion locates specific modifications along the sequence. Circular dichroism provides a secondary-structure profile, although it gives limited information about local conformational changes.
Quality control for peptide material focuses on identity, purity, content and the profile of impurities. Common degradants include deamidated and oxidised forms, plus aggregates formed during storage or handling. Forced degradation studies under heat, light, acid and peroxide help define which conditions accelerate change and which analytical methods detect it. Limits for individual impurities are set by pharmacopoeial monographs or manufacturer specifications. How much a given impurity affects biological activity is often uncertain, and conclusions may depend on the assay used.
Lyophilised semaglutide is generally held at -20 °C or below, protected from light and moisture. Reconstituted solutions are typically kept at 2-8 °C and used within a defined window because degradation accumulates over time. Repeated freeze-thaw cycles are discouraged, since each cycle can promote aggregation and reduce monomeric content. Room-temperature stability of the solid has been examined in some studies but remains incompletely characterised for long durations, so cold storage is the conservative default for research material.
Degradation proceeds along several parallel routes. Deamidation of asparagine and glutamine residues generates charged variants that shift retention time in chromatographic analysis. Oxidation targets methionine and can be accelerated by trace metals or dissolved oxygen. Non-covalent aggregation produces dimers, oligomers, and larger species that are difficult to reverse. Isomerisation at aspartate residues is slower but measurable under thermal stress. The distribution among these pathways depends on pH, buffer composition, ionic strength, and the presence of excipients such as sugars or surfactants.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white lyophilised powder | Visual inspection under suitable light |
| Aqueous solubility | Soluble, pH dependent | Dissolves readily in neutral buffer |
| Storage temperature | 2-8 °C short term; -20 °C or below long term | Protect from light and moisture |
| Primary purity method | Reversed-phase HPLC | UV detection near 214 nm |
| Identity confirmation | LC-MS with peptide mapping | Mass accuracy within a few ppm |
Identity and purity are assessed with reversed-phase high-performance liquid chromatography, which separates the peptide from related impurities by hydrophobicity. Mass spectrometry confirms molecular weight and detects truncation or modification products. Peptide mapping after enzymatic digestion verifies the amino acid sequence. Quantitation is often performed by LC-MS/MS or by immunoassay, and the two approaches can give different values because they measure different things. Method validation parameters such as accuracy, precision, and limit of quantitation are reported alongside results.
Certificate of analysis documents from suppliers typically report purity by chromatographic area, water content, and counter-ion identity. Independent verification is advisable because reported values can be generated under differing conditions. Impurity profiles matter for research use, where aggregates, deamidation products, and residual solvents may influence experimental results. Container, lot, and chain-of-custody records support traceability. Analytical results are method-dependent, so comparisons between laboratories require the same procedure and reference standards.
Quantification and purity assessment rely on separation methods coupled to optical or mass detection. Reversed-phase high-performance liquid chromatography resolves the intact peptide from related impurities and is the standard assay technique. Size-exclusion chromatography measures aggregates, while ion-exchange chromatography separates charge variants produced by deamidation. Mass spectrometry confirms identity and detects mass shifts of a few daltons. In biological matrices, liquid chromatography with tandem mass spectrometry is often used because immunoassays can cross-react with endogenous GLP-1 or with circulating fragments.
As a peptide, semaglutide is sensitive to conditions that break amide bonds or modify side chains. Deamidation of asparagine and glutamine residues, oxidation of methionine and tryptophan, and non-covalent aggregation are the main degradation routes described in published stability work. Rate depends strongly on pH, buffer species, ionic strength, temperature and exposure to light. Formulators therefore choose a defined solution pH and often add excipients such as phosphate buffer, propylene glycol and phenol, each of which plays a separate role in pH control, tonicity or preservation.
Handling guidance for research quantities calls for single-use aliquots, an inert atmosphere where practical, and avoidance of repeated freeze-thaw cycles that accelerate aggregation. Certificates of analysis typically report purity by peak area, water content, counter-ion identity, and residual solvent levels. In the scientific literature the compound is usually described by its full amino acid sequence, its registry number, or its structural class rather than by any proprietary label. Reporting standards vary between journals, and reviewers increasingly request raw chromatograms alongside tabulated purity figures. Whether current purity thresholds are adequate for every experimental context is debated.
Reversed-phase high-performance liquid chromatography with ultraviolet detection is the dominant approach for peptide purity assessment, usually paired with mass spectrometry to confirm molecular mass and sequence. Peptide mapping by enzymatic digestion and tandem mass spectrometry locates modifications such as deamidation and oxidation. Quantitation in plasma matrices can be performed by LC-MS/MS after solid-phase extraction. Method validation follows general guidance on accuracy, precision, linearity, and limits of detection. Comparability of results between laboratories, when no shared reference standard is available, remains an open question.
Elion (1918–1999), American biochemist and recipient of the 1988 Nobel Prize in Physiology or Medicine for innovative methods of rational drug design Conrad Elvehjem (1901–1962), American biochemist who identified two vitamins, nicotinic acid (niacin) and nicotinamide Harry Julius Emeléus (1903–1993), British inorganic chemist known for work on fluorine chemistry Gladys Anderson Emerson (1903–1984), American chemist and early nutritionist, and the first person to isolate Vitamin E Emil Erlenmeyer (1825–1909), German chemist known for the early development of the theory of chemical structure and formulating the Erlenmeyer rule. Richard R. Ernst (1933–2021), Swiss physical chemist, 1991 Nobel Prize in Chemistry for the development of Fourier transform nuclear magnetic resonance spectroscopy Gerhard Ertl (born 1936), German physical chemist who laid the foundation of modern surface chemistry, 2007 Nobel prize in chemistry Margaret C. Etter (1943–1992), American chemist and developer of solid state chemistry for crystalline organic compounds Hans von Euler-Chelpin (1873–1964), Swedish chemist, winner of the 1929 Nobel Prize in Chemistry for work on the fermentation of sugar and enzymes Henry Eyring (1901–1981), Mexico-born American theoretical chemist known for the absolute rate theory of chemical reactions
== Physiology == Free fatty acids (FFAs) are liberated from lipoproteins by lipoprotein lipase (LPL) and enter the adipocyte, where they are reassembled into triglycerides by esterifying them onto glycerol. Human fat tissue contains from 61% to 94% lipids. Lean and obese individuals tend towards the low and high ends of this range, respectively. There is a constant flux of FFAs entering and leaving adipose tissue. The net direction of this flux is controlled by insulin and leptin—if insulin is elevated, then there is a net inward flux of FFA, and only when insulin is low can FFA leave adipose tissue. Insulin secretion is stimulated by high blood sugar, which results from consuming carbohydrates. In humans, lipolysis (hydrolysis of triglycerides into free fatty acids) is controlled through the balanced control of lipolytic B-adrenergic receptors and a2A-adrenergic receptor-mediated antilipolysis. Fat cells have an important physiological role in maintaining triglyceride and free fatty acid levels, as well as determining insulin resistance. Abdominal fat has a different metabolic profile—being more prone to induce insulin resistance. This explains to a large degree why central obesity is a marker of impaired glucose tolerance and is an independent risk factor for cardiovascular disease (even in the absence of diabetes mellitus and hypertension). Recent advances in biotechnology have allowed for the harvesting of adult stem cells from adipose tissue, allowing stimulation of tissue regrowth using a patient's own cells.
Microfluidic devices with 2D or 3D cell cultures can be used to analyze spheroids for different cancer systems (such as lung cancer and ovarian cancer), and are essential for multiple anti-cancer drugs and toxicity tests. This strategy can be improved by increasing the throughput and production of spheroids. For example, one droplet-based microfluidic device for 3D cell culture produces 500 spheroids per chip. These spheroids can be cultured longer in different surroundings to analyze and monitor. The other advanced technology is organs‐on‐a‐chip, and it can be used to simulate several organs to determine the drug metabolism and activity based on vessels mimicking, as well as mimic pH, oxygen... to analyze the relationship between drugs and human organ surroundings. One strategy relevant to single-cell chromatin immunoprecipitation (ChiP)‐Sequencing is droplets, which operates by combining droplet‐based single cell RNA sequencing with DNA‐barcoded antibodies, possibly to explore the tumor heterogeneity by the genotype and phenotype to select the personalized anti-cancer drugs and prevent the cancer relapse.
==== Colombia ==== Caldo de raíz (lit. 'root soup') or caldo peligroso (lit. 'dangerous broth') is a Colombian cuisine bull penis and testicles soup. The soup is cooked for hours with potatoes, peas, and occasionally beans. Caldo de raíz is eaten as an aphrodisiac.
== Engineering == In biochemical engineering, sparging can remove low-boiling liquids from a solution. The low-boiling components evaporate more rapidly, so the gas bubbles remove more of them from the bulk solution containing higher-boiling components. It is an alternative to distillation, and it does not require heat.
Sources: en.wikipedia.org
== Early life and education == James William Middleton was born on 15 April 1987 at the Royal Berkshire Hospital in Reading, the youngest child and only son of Michael Middleton (born 1949), a former British Airways flight dispatcher, and Carole Middleton (born 1955), a former flight attendant. His father came from a line of solicitors who lived in Leeds, West Yorkshire. His great-grandmother Olive Middleton was a member of the Lupton family, who were landed gentry. His mother's family were from County Durham. Shortly before his birth, Middleton's parents founded Party Pieces, a mail-order party supply company. His elder sisters are Catherine (born 1982) and Philippa (born 1983). The family lived in Bradfield Southend, Berkshire, before moving to the nearby village of Bucklebury in 1995. Middleton was educated at St Andrew's School, Pangbourne, and Marlborough College. In 2006, he attended the University of Edinburgh, studying environmental resources management before dropping out a year later.
Millimoles per liter (mmol/L) is the SI standard unit used in most countries around the world. Milligrams per deciliter (mg/dL) is used in some countries such as the United States, Japan, France, Egypt, and Colombia. Scientific journals are moving toward using mmol/L; some journals now use mmol/L as the primary unit but quote mg/dL in parentheses. Glucose levels vary before and after meals, and at various times of day; the definition of "normal" varies among medical professionals. In general, the normal range for most people (fasting adults) is about 4 to 6 mmol/L or 80 to 110 mg/dL. (where 4 mmol/L or 80 mg/dL is "optimal".) A subject with a consistent range above 7 mmol/L or 126 mg/dL is generally held to have hyperglycemia, whereas a consistent range below 4 mmol/L or 70 mg/dL is considered hypoglycemic. In fasting adults, blood plasma glucose should not exceed 7 mmol/L or 126 mg/dL. Sustained higher levels of blood sugar cause damage to the blood vessels and to the organs they supply, leading to the complications of diabetes. Chronic hyperglycemia can be measured via the HbA1c test. The definition of acute hyperglycemia varies by study, with mmol/L levels from 8 to 15 (mg/dL levels from 144 to 270). Defects in insulin secretion, insulin action, or both, results in hyperglycemia. Chronic hyperglycemia can be measured by clinical urine tests which can detect sugar in the urine or microalbuminuria which could be a symptom of diabetes.
Zinc sheet metal is used as a durable covering for roofs, walls, and countertops, the last often seen in bistros and oyster bars, and is known for the rustic look imparted by its surface oxidation in use to a blue-gray patina and susceptibility to scratching. 64Zn, the most abundant isotope of zinc, is very susceptible to neutron activation, being transmuted into the highly radioactive 65Zn, which has a half-life of 244 days and produces intense gamma radiation. Because of this, zinc oxide used in nuclear reactors as an anti-corrosion agent is depleted of 64Zn before use, this is called depleted zinc oxide. For the same reason, zinc has been proposed as a salting material for nuclear weapons (cobalt is another, better-known salting material). A jacket of isotopically enriched 64Zn would be irradiated by the intense high-energy neutron flux from an exploding thermonuclear weapon, forming a large amount of 65Zn significantly increasing the radioactivity of the weapon's fallout. Such a weapon is not known to have ever been built, tested, or used. 65Zn is used as a tracer to study how alloys that contain zinc wear out, or the path and the role of zinc in organisms. Zinc dithiocarbamate complexes are used as agricultural fungicides; these include Zineb, Metiram, Propineb and Ziram. Zinc naphthenate is used as wood preservative. Zinc in the form of ZDDP, is used as an anti-wear additive for metal parts in engine oil.
The combination of an inappropriate rapid heart rate response to exercise with heavy or rapid breathing is known as an exaggerated cardiorespiratory response to exercise. Due to the confusion between muscle fatigue and muscle weakness, there have been instances of abnormal muscle fatigue being described as exercise-induced muscle weakness.
Sources: en.wikipedia.org
== Bibliography == McNeill, A; Brose, LS; Calder, R; Bauld, L; Robson, D (February 2018). "Evidence review of e-cigarettes and heated tobacco products 2018" (PDF). UK: Public Health England. pp. 1–243. Stratton, Kathleen; Kwan, Leslie Y.; Eaton, David L. (January 2018). Stratton, Kathleen; Kwan, Leslie Y.; Eaton, David L. (eds.). Public Health Consequences of E-Cigarettes (PDF). National Academies of Sciences, Engineering, and Medicine (National Academies Press). pp. 1–774. Bibcode:2018nap..book24952N. doi:10.17226/24952. ISBN 978-0-309-46834-3. PMID 29894118. McNeill, A; Brose, LS; Calder, R; Hitchman, SC; Hajek, P; McRobbie, H (August 2015). "E-cigarettes: an evidence update" (PDF). UK: Public Health England. pp. 1–113. "Electronic Nicotine Delivery Systems and Electronic Non-Nicotine Delivery Systems (ENDS/ENNDS)" (PDF). World Health Organization WHO. August 2016. pp. 1–11. Wilder, Natalie; Daley, Claire; Sugarman, Jane; Partridge, James (April 2016). "Nicotine without smoke: Tobacco harm reduction". UK: Royal College of Physicians. pp. 1–191. "State Health Officer's Report on E-Cigarettes: A Community Health Threat" (PDF). California Tobacco Control Program. California Department of Public Health. January 2015. pp. 1–21. This article incorporates text from this source, which is in the public domain.
elongation Also extension. The linear growth of a nucleic acid polymer by the sequential addition of individual nucleotide monomers to a nascent strand, e.g. during transcription or replication, especially when it occurs by complementary pairing with a template strand. The term is often used to describe steps in certain laboratory techniques such as the polymerase chain reaction.
The earliest known reference to morphine can be traced back to Theophrastus in the 3rd century BC, however, possible references to morphine may go as far back as 2100 BC as Sumerian clay tablets which records lists of medical prescriptions including opium-based cures. An opium-based elixir has been ascribed to alchemists of Byzantine times, but the specific formula was lost during the Ottoman conquest of Constantinople (Istanbul). Around 1522, Paracelsus made reference to an opium-based elixir that he called laudanum from the Latin word laudāre, meaning "to praise". He described it as a potent painkiller but recommended that it be used sparingly. The recipe given differs substantially from that of modern-day laudanum. Morphine was discovered as the first active alkaloid extracted from the opium poppy plant in December 1804 in Paderborn by German pharmacist Friedrich Sertürner. Sertürner noticed the compound induced drowsiness in rats and stray dogs and he reported his findings in 1805. In 1817, Sertürner reported experiments in which he administered morphine to himself, three young boys, three dogs, and a mouse; all four people almost died. Sertürner originally named the substance morphium after the Greek god of dreams, Morpheus, as it has a tendency to cause sleep. Sertürner's morphium was six times stronger than opium. He hypothesized that, because lower doses of the drug were needed, it would be less addictive.
Plants produce chemicals at the injury site that signal the presence of damage and may help to reduce further damage. The chemicals involved depend to some extent on the plant species, though several of them are shared among species; and the signals given depend on the cause of the injury. Plants injured by spider mites release volatile chemicals that attract predatory mites, serving to reduce the attack on the plants. As another example, maize plants damaged by the caterpillars of noctuid moths release a mixture of terpenoid substances which attract the parasitoid wasp Cotesia marginiventris, which kills caterpillars. Many plants give off such herbivory-induced signals.
== Validation Master Plan == The Validation Master Plan is a document that describes how and when the validation program will be executed in a facility. Even though it is not mandatory, it is the document that outlines the principles involved in the qualification of a facility, defines the areas and systems to be validated and provides a written program for achieving and maintaining a qualified facility with validated processes. It is the foundation for the validation program and should include process validation, facility and utility qualification and validation, equipment qualification, cleaning and computer validation. The regulations also set out an expectation that the different parts of the production process are well defined and controlled, such that the results of that production will not substantially change over time.
Sources: en.wikipedia.org
Lower temperatures slow hydrolysis, oxidation and aggregation reactions that degrade the molecule over time. Lyophilised powder is more tolerant than solution, but both benefit from controlled conditions.
Mass spectrometry and peptide mapping are commonly used, often alongside chromatographic retention time comparison. No single technique covers both sequence and higher-order structure.
Aggregation is monitored because it can alter activity and may influence immune responses. Size-exclusion chromatography and related techniques are used to quantify it.
Reverse-phase high-performance liquid chromatography with ultraviolet detection is the usual choice, with results reported as area percent. Complementary methods such as size-exclusion chromatography and mass spectrometry are needed because a single separation cannot resolve every impurity class. Purity figures are therefore method dependent and should always be read alongside the technique used.