This is a working overview of deamidation, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-04-02. Anything still debated is marked as such rather than presented as settled.
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.
Stability studies focus on deamidation of asparagine and glutamine residues, oxidation of methionine, and aggregation into higher-order species. The fatty acid side chain adds susceptibility to oxidative change and can promote self-association at high concentration. Lyophilised material is comparatively robust when kept cold and dry, while aqueous solutions require refrigeration and protection from light. Forced degradation experiments under heat, acid, base, and peroxide conditions establish the specificity of each analytical method. Which degradation route dominates under real storage conditions depends on the formulation and stays formulation-specific.
皮下注射后吸收相对缓慢，绝对生物利用度约为百分之八十九，血药浓度峰值通常出现在给药后一到三天。与白蛋白结合使清除减慢，终末半衰期约为一百六十五小时，接近一周。连续给药约四到五周后达到稳态暴露水平。表观分布容积约为每千克零点二五升，血浆蛋白结合率超过百分之九十九。代谢以蛋白水解切割和脂肪二酸侧链的 β-氧化为主，相关产物主要经尿液与粪便排出。
序列层面的改动同时解决了两个问题，即酶解稳定性与肾脏清除速度。天然 GLP-1 在循环中的半衰期仅约两分钟，主要被二肽基肽酶-4 迅速灭活。酰化侧链与白蛋白的可逆结合形成循环储库，使分子缓慢释放并持续激活受体。这种设计思路后来被广泛用于同类长效肽的开发，属于该类药物化学改造的典型范式。
Semaglutide 是一种经结构修饰的胰高血糖素样肽-1 类似物，其主链与内源性 GLP-1(7-36) 约有百分之九十四的序列一致性。第 8 位丙氨酸被 α-氨基异丁酸取代，使二肽基肽酶-4 无法识别原有切割位点。第 34 位赖氨酸换为精氨酸，进一步降低酶解速率。第 26 位赖氨酸经间隔基连接一条含十八个碳的二酸脂肪链，该侧链赋予分子与血浆白蛋白结合的能力。
| Property | Value | Notes |
|---|---|---|
| Typical purity assay | reversed-phase HPLC, 220 nm | Amide-bond detection for the peptide backbone |
| Identity confirmation | electrospray mass spectrometry | Peptide mapping used for sequence coverage |
| Related substances | deamidated and oxidised forms | Truncated sequences also monitored |
| Powder storage | -20 degrees Celsius | Keep sealed, dry, and protected from light |
| Solution storage | 2 to 8 degrees Celsius | Avoid repeated freeze-thaw cycling |
== Future == In May 2022, The Hollywood Reporter confirmed that Åkerlund would return to direct another film adaptation, The Black Kaiser, which its producers said would not be "a sequel or a prequel". Mikkelsen was set to reprise his role and co-write the screenplay with Jayson Rothwell, though it was later reported that only Rothwell was writing the film. One year later, Variety reported that Derrick Borte had replaced Åkerlund as director and that Hudgens would appear in the film. Filming was set to begin in the third quarter of 2023.
=== Lactose fermentation === In one study that sought to prove that some fermentation produced by L. lactis can hinder motility in pathogenic bacteria, the motilities of Pseudomonas, Vibrio, and Leptospira strains were severely disrupted by lactose utilization on the part of L. lactis. Using flagellar Salmonella as the experimental group, the research team found that a product of lactose fermentation is the cause of motility impairment in Salmonella. It is suggested that the L. lactis supernatant mainly affects Salmonella motility through disruption of flagellar rotation rather than through irreversible damage to morphology and physiology. Lactose fermentation by L. lactis produces acetate that reduces the intracellular pH of Salmonella, which in turn slows the rotation of their flagella. These results highlight the potential use of L. lactis for preventing infections by multiple bacterial species.
=== Digestive system === Arenobufagin has shown to cause appoptose in hepatocellular carcinoma cells in mice, although this method is not used to cure hepatocellular carcinoma in modern human medicine.
A Possible start codons in NCBI table 1. ATG is most common. The two other start codons listed by table 1 (GTG and TTG) are rare in eukaryotes. Prokaryotes have less strigent start codon requirements; they are described by NCBI table 11. B ^ ^ ^ The historical basis for designating the stop codons as amber, ochre and opal is described in an autobiography by Sydney Brenner and in a historical article by Bob Edgar.
Crystallization analysis fractionation (CRYSTAF): instrument intended for the fast measurement of the chemical composition distribution (CCD) in polyolefins (crystallization analysis fractionation). Temperature rising elution fractionation (TREF): for the characterization of CCD in polyolefins. Crystallization elution fractionation (CEF): high-throughput chemical composition distribution analyzer by CEF TGIC: technique for the analysis of low crystallinity polyolefins implemented by a fully automated instrument. Molar mass distribution GPC-IR: high temperature gel permeation chromatography (GPC) for polyolefin molar mass distribution. It works with concentration and composition detectors (infrared), viscometer and light scattering. GPC One: GPC calculations software. Data Unit 200: signals device for gel permeation chromatography instruments. GPC-QC: simplified and fully automated GPC instrument aimed at control laboratories in polyolefin production plants. Intrinsic viscosity IVA: automated instrument for intrinsic viscosity analysis of polymers with dissolution temperature up to 200 °C. Bivariate distribution Cross-fractionation chromatography(CFC) instrument to analyze the polyolefin bivariate distribution by TREF and gel permeation chromatography. SGIC 2D: 3D results with the advantages of using an IR detector for this new tool aimed at polyolefin characterization. Preparative fractionation PREP mc2: preparative instrument to fractionate polymers by molar mass or composition (TREF or CRYSTAF).
Sources: en.wikipedia.org
=== Exhaustion === T cell exhaustion is a poorly defined or ambiguous term. There are three approaches to its definition. "The first approach primarily defines as exhausted the cells that present the same cellular dysfunction (typically, the absence of an expected effector response). The second approach primarily defines as exhausted the cells that are produced by a given cause (typically, but not necessarily, chronic exposure to an antigen). Finally, the third approach primarily defines as exhausted the cells that present the same molecular markers (typically, programmed cell death protein 1 [PD-1])." Indeed, it is now starting to emerge that exhaustion might not be the only T cell dysfunctional state. In fact, tolerization, anergy, cell death, ignorance, senesence and exclusion have recently emerged as additional sources and/or states of T cell dysfunction in cancer and chronic viral infection. Dysfunctional T cells are characterized by progressive loss of function, changes in transcriptional profiles and sustained expression of inhibitory receptors. At first, cells lose their ability to produce IL-2 and TNFα, which is followed by the loss of high proliferative capacity and cytotoxic potential, and eventually leads to their deletion. Exhausted T cells typically indicate higher levels of CD43, CD69 and inhibitory receptors combined with lower expression of CD62L and CD127. Exhaustion can develop during chronic infections, sepsis and cancer. Exhausted T cells preserve their functional exhaustion even after repeated antigen exposure.
==== England (1920, 1923, 1925, 1935, 1938, 1946) ==== Constance Long arranged for Jung to deliver a seminar in Cornwall in 1920. Another seminar was held in 1923, this one organized by Jung's British protégé Helton Godwin Baynes (known as "Peter") (1882–1943), and another in 1925.
Li R, Bianchet MA, Talalay P, Amzel LM (1995). "The three-dimensional structure of NAD(P)H:quinone reductase, a flavoprotein involved in cancer chemoprotection and chemotherapy: mechanism of the two-electron reduction". Proc. Natl. Acad. Sci. U.S.A. 92 (19): 8846–50. Bibcode:1995PNAS...92.8846L. doi:10.1073/pnas.92.19.8846. PMC 41064. PMID 7568029.
The first reference in the literature to a commercially available protein A chromatography resin appeared in 1976. Today, chromatographic separation using protein A immobilized on porous substrates is the most widely established method for purifying monoclonal antibodies (mAbs) from harvest cell culture supernatant. The choice of protein A as the preferred method is due to the high purity and yield which are easily and reliably achieved. This forms the basis for a general antibody purification "platform" which simplifies manufacturing operations and reduces the time and effort required to develop purification processes. A typical mAb purification process is shown at right. Albeit the long history of protein A chromatography for the production of antibodies, the process is still being improved today. Continuous chromatography, more precisely periodic counter-current chromatography, enormously increases the productivity of the purification step.
Sources: en.wikipedia.org
=== Cyanotoxins === In recent years, there has been an increase of cyanobacterial blooms due to the eutrophication (or increase in nutrient levels) of surface waters around the world. Increases in certain nutrients, such as nitrogen and phosphorus, are linked to fertilizer runoff from agricultural fields, and are also found in certain products, such as detergents, in urban spaces. These blooms can release toxins that can decrease water quality and are a risk to human and wildlife health. Additionally, there are a lack of regulations regarding the maximum contaminant levels (MCL) allowed in drinking water sources. Cyanotoxins can have both acute and chronic toxic effects, and there are often many consequences for the health of the environment where these blooms occur.
== Biography == Robert Brownlee was born October 21, 1942, in South Dakota. He founded Brownlee Labs in the 1970s, in the San Francisco Bay area, a manufacturer of columns and pumps for high-performance liquid chromatography systems. Bob Brownlee took the initiative "along with Tom Jupille, Steve Bakalyar, Nelson Cooke, Jerry Higgins and Ron Majors" to form the Bay Area Chromatography Colloquium. Bob Stevenson is quoted as saying in his Nine Lives of the California Separation Science Society that Brownlee Labs was "certainly one of the globe's leaders in HPLC column technology." In the 1980s, when Robert Brownlee was diagnosed with AIDS-related complex, he sold his company to Applied Biosystems of Foster City, California, in 1984. (Applied later merged with Perkin-Elmer). Sometime later, he began a new company, which was viewed by Applied as a competitor. A lawsuit was instituted and later settled (Brownlee v. Applied Biosystems, Inc., 1989-1 Trade Cas. (CCH) ¶ 68, (N.D. Cal. 1989) 8,14). In 1990, he was interviewed for an article in The Scientist about Applied Biosystems. "If you produce the first product for these virgins [scientists without such equipment], you have a big value added, and you can charge a big price for your product," Brownlee says. "That's the reason Applied Biosystems did so well." He also formed the Robert Brownlee Foundation, a private family foundation which supports, with grants, K–12 science.
Bavington, Dean L. Y. Managed Annihilation: An Unnatural History of the Newfoundland Cod Collapse (University of British Columbia Press; 2010) 224 pages. Links the collapse of Newfoundland and Labrador cod fishing to state management of the resource. Cobb, John N. (1916). Pacific Cod Fisheries. Bureau of Fisheries Document. Vol. 830. Washington, DC: Government Printing Office. OCLC 14263968. Greenberg, Paul (2010). Four Fish: The Future of the Last Wild Food. New York: Penguin Press. ISBN 978-1-59420-256-8. OCLC 813929026. Mark Kurlansky (1997). Cod: A Biography of the Fish That Changed the World. Shields, Edward (2001). Salt of the Sea: The Pacific Coast Cod Fishery and the Last Days of Sail. Lopez Island, Wash.: Heritage House. ISBN 978-1-894384-35-3.
Sources: en.wikipedia.org
Purity is commonly expressed as the percentage of the main peak relative to all integrated peaks in a reversed-phase chromatogram. Related substances and counter-ions are reported separately. Values obtained with different detectors are not always directly comparable.
Aggregation is driven by hydrophobic contacts, especially those involving the fatty acid side chain, and is accelerated by heat, agitation, and repeated freezing and thawing. Low pH and suitable excipients can reduce the rate. The tendency differs between formulations.
Dry powder has low molecular mobility and tolerates colder storage for longer periods. Water enables hydrolysis and conformational change, so dissolved material is kept refrigerated and used within a shorter window.
差别集中在三处：第 8 位残基被非天然氨基酸取代，第 34 位换成精氨酸，第 26 位增加一条脂肪酸侧链。前两处改动降低酶解速率，侧链则通过白蛋白结合延长循环时间。综合结果是半衰期从约两分钟延长到约一周。