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 2026-08-01 and is reviewed periodically as new material appears.
Peptide handling begins with careful receipt and inventory. Containers should be inspected for damage, label information should match the certificate of analysis, and storage location should be recorded. Many lyophilized peptides are electrostatic and may cling to vial walls or weighing paper, which can complicate transfer. Allowing a cold vial to equilibrate to room temperature before opening reduces condensation on the contents. Clean tools, gloves, and a low-humidity workspace limit contamination and moisture exposure during manipulation.
Reconstitution is the process of dissolving a dried peptide in a suitable solvent. The choice of solvent depends on solubility, charge, and sequence; sterile water is common, while buffers or small amounts of organic solvent may be needed for hydrophobic peptides. Adding solvent gently down the vial wall and mixing by inversion or gentle swirling reduces foaming and shear. Vortexing or vigorous pipetting can denature some peptides or promote aggregation. The resulting solution should be visually inspected for particles, turbidity, and complete dissolution before use.
After reconstitution, solutions are usually divided into single-use aliquots to avoid repeated freeze-thaw cycles. Aliquots should be labeled with peptide identity, concentration, solvent, and date, then stored at the temperature specified by the supplier or protocol. Many peptides tolerate -20 °C for short periods, while -80 °C is preferred for longer storage. Frost-free freezers are generally avoided because temperature fluctuations can stress samples. Aseptic technique and sterile filters reduce microbial contamination, though filtration can also remove aggregated material or bind some 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 |
|---|---|---|
| Reconstitution solvent | Sterile water or aqueous buffer | Organic cosolvent may be needed for hydrophobic sequences |
| pH adjustment | Sequence-dependent | Test small volumes before preparing the full solution |
| Filtration | 0.22 µm sterile filter | Can remove particles but may bind or remove aggregates |
| Aliquot size | Single-use volume | Reduces repeated freeze-thaw cycles |
| Post-reconstitution storage | -20 °C to -80 °C | Follow supplier or protocol; avoid frost-free cycles |
Handling begins with receipt and inspection. Vials should be checked for damage, label integrity, and temperature history. Lyophilized peptides should be allowed to equilibrate to room temperature before opening to prevent condensation. Solutions should be prepared in a clean, calibrated environment using appropriate solvents. Personal protective equipment and containment reduce exposure and contamination. Documentation of lot number, date, and storage location supports traceability. The goal is to limit repeated temperature changes, moisture exposure, and microbial contamination.
Reconstitution solvent depends on peptide solubility and intended use; water, buffer, or small amounts of organic solvent may be needed. After dissolution, solutions are typically aliquoted into single-use portions to avoid repeated freeze-thaw cycles. Aliquots are stored at -20 °C or -80 °C, depending on stability. Labels include concentration, solvent, date, and operator. Sterile filtration may be used when microbial control is required, but filters can adsorb peptides. The optimal concentration and solvent are often determined empirically.
Cold-chain shipping uses insulated containers, phase-change packs, and temperature indicators. Dry ice maintains -70 °C or lower but requires venting to avoid pressure buildup. Gel packs provide 2-8 °C for shorter transit. Upon arrival, recipients should record temperature indicators and transfer vials promptly to storage. Deviations from specified conditions should be documented and may require analytical re-check. The effect of a brief temperature excursion is peptide-specific and not always predictable from general rules.
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.
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.
Receiving a peptide shipment requires immediate inspection of the packaging and temperature indicators. Any deviation from the specified cold chain should be documented and investigated. Upon arrival, solid peptides are generally kept at -20°C, whereas liquid formulations are stored at -80°C. Vials should be kept upright and protected from light. Repeated warming and cooling of the entire container is avoided by preparing smaller working aliquots. A log of lot numbers, receipt dates, and storage locations supports traceability and quality control.
Reconstitution is a critical handling step. The appropriate solvent—often sterile water, phosphate-buffered saline, or a water-acetonitrile mixture—is chosen based on peptide solubility. Adding solvent gently down the vial wall and swirling, rather than vortexing, reduces foaming and shear stress. The resulting solution should be clear; visible particles indicate incomplete dissolution or contamination. Concentration is recorded accurately because it affects subsequent use. If the peptide is not fully soluble, a small amount of organic solvent or a different buffer may be required, but this changes the final composition.
=== Major hormones === Neurokinin B (a tachykinin peptide) and kisspeptin (a neuropeptide), both present in KNDy neurons of the hypothalamus, are critical parts of the control system that switches on the release of GnRH at the start of puberty. GnRH (gonadotropin-releasing hormone) is a peptide hormone released from the hypothalamus which stimulates gonadotrope cells of the anterior pituitary. LH (luteinizing hormone) is a larger protein hormone secreted into the general circulation by gonadotrope cells of the anterior pituitary gland. The main target cells of LH are the Leydig cells of testes and the theca cells of the ovaries. LH secretion changes more dramatically with the initiation of puberty than FSH, as LH levels increase about 25-fold with the onset of puberty, compared with the 2.5-fold increase of FSH. FSH (follicle stimulating hormone) is another protein hormone secreted into the general circulation by the gonadotrope cells of the anterior pituitary. The main target cells of FSH are the ovarian follicles and the Sertoli cells and spermatogenic tissue of the testes. Testosterone is a steroid hormone produced primarily by the Leydig cells of the testes, and in lesser amounts by the theca cells of the ovaries and the adrenal cortex. Testosterone is the primary mammalian androgen and the "original" anabolic steroid. It acts on androgen receptors in responsive tissue throughout the body. Estradiol is a steroid hormone produced by aromatization of testosterone. Estradiol is the principal human estrogen and acts on estrogen receptors throughout the body.
In business and investing, a megacap stock (also mega-cap or mega cap) is a stock whose market capitalization (market cap) is among the very largest. These are stocks of the largest publicly traded companies in the world. The market capitalization of a stock is the total value of the shares outstanding, calculated as (shares outstanding x share price). Stocks with large market caps, but smaller than megacaps, instead fall within the large-cap segment of the stock market. There is no official definition of, or full consensus agreement about, the exact market cap cutoff value for a stock to qualify as megacap, and it may vary internationally. However, for the 2020s US market, a minimum market cap value of $200 billion is often cited. Index providers, investment funds, and investment managers may have other definitions.
==== Electronics ==== An aqueous solution of copper(II) sulfate is often used as the resistive element in liquid resistors. In electronic and microelectronic industry a bath of CuSO4·5H2O and sulfuric acid (H2SO4) is often used for electrodeposition of copper.
== Biosynthesis == PPG is produced by enzymes of two gene clusters. Recent work on the peptide ligases show, surprisingly, a common origin with murein synthesis. The pathway is now known to include the orthologous-to-bacteria CarB, MurC/D (peptide ligase), MurG, MraY, UppP, UppS, and flippase presumably performing an analogous function, and two novel but conserved transmembrane proteins. GlmM and GlmU, which produce UDP-GlcNAc in bacteria, are also present with phosphoglucomutase (PGM). Half of the species also have MurT and GatD, known to perform cell wall modifications in bacteria. No orthologous cross-linking enzymes have been identified. Notably, "formation of the disaccharide moiety of the glycopeptide monomer occurs before the transfer to membrane protein by MraY", as opposed to after in bacteria. Further work would be needed to connect these information into a coherent pathway.
Sources: en.wikipedia.org
== Social == Social Progress Index 2017: Thailand ranked 62 of 128 nations (1=best; 128=worst). Other ASEAN nations ranked were: Malaysia, 50; Philippines, 68; Indonesia, 79; Myanmar, 96; Cambodia, 98; and Laos, 99. Social Progress Index 2015: Social progress is the capacity of a society to meet the basic human needs of its citizens. Thailand ranked 57 of 113 nations (1=best; 133=worst). Other ASEAN states were ranked: Philippines, 64; Indonesia, 86; Cambodia, 99; Laos, 102; and Myanmar, 119. Social Progress Index 2014: Thailand ranked 59 of 132 countries State of the World's Mothers 2014: Ranked 72 of 178 countries.
Many marine invertebrates feed on carrion including cephalopods (e.g. Octopus vulgaris), hermit crabs (e.g. Coenobita perlatus), squat lobsters (e.g. Munida tenuimana), star fish (e.g. Asterias rubens), sea anemones (e.g. Actinoscyphia aurelia), amphipods (e.g. Eurythenes gryllus), annelids (e.g. zombie worms), and ribbon worms (e.g. Parborlasia corrugatus). Types of carrion consumed include dead seals, pilchards, jellyfish and tunicates, bones from whale falls, and fishery discards such as whiting and langoustine. Marine necrophages are less useful in forensic science than terrestrial necrophages. This is partly because human deaths occur less frequently in marine settings than terrestrial settings, and partly because human remains are less likely to be recovered in marine settings. In addition, in any aquatic system, there are a large number of environmental and biological factors that can confound calculation of minimum post-mortem interval. These include current and wave action, water temperature, oxygen concentration, and a greater diversity of necrophagous organisms colonizing the remains.
== Metabolism == Most members of the genus Haemophilus require at least one of these blood factors for growth: hemin (sometimes called 'X-factor') and/or nicotinamide adenine dinucleotide (NAD; sometimes called 'V-factor'); they usually will not grow on blood agar plates. While NAD is released into blood agar by red blood cells, hemin is bound to the blood cells and is unavailable to bacteria in this medium which prevents the growth of many Haemophilus species. They are unable to synthesize important parts of the cytochrome system needed for respiration, and they obtain these substances from the heme fraction of blood hemoglobin. Clinical laboratories use tests for the hemin and NAD requirement to identify the isolates as Haemophilus species. The species Haemophilus haemoglobinophilus is an exception to this, as it has been shown to grow well on both blood and chocolate agars. Chocolate agar is an excellent Haemophilus growth medium, as it allows for increased accessibility to these factors. Alternatively, Haemophilus is sometimes cultured using the "Staph streak" technique: both Staphylococcus and Haemophilus organisms are cultured together on a single blood agar plate. In this case, Haemophilus colonies will frequently grow in small "satellite" colonies around the larger Staphylococcus colonies because the metabolism of Staphylococcus produces the necessary blood factor byproducts required for Haemophilus growth.
Sources: en.wikipedia.org
With oral administration, progesterone is rapidly metabolized in the gastrointestinal tract and liver. As many as 30 different metabolites have been found to be formed from progesterone with oral ingestion. Regardless of the route of administration, 5α-reductase is the major enzyme involved in the metabolism of progesterone and is responsible for approximately 60 to 65% of its metabolism. 5β-Reductase is also a major enzyme in the metabolism of progesterone. 5α-Reduction of progesterone occurs predominantly in the intestines (specifically the duodenum), whereas 5β-reduction occurs almost exclusively in the liver. The metabolites of progesterone produced by 5α-reductase and 5β-reductase (after further transformation by 3α-hydroxysteroid dehydrogenase) are allopregnanolone and pregnanolone, respectively. With oral administration of progesterone, they occur in circulation at very high and in fact supraphysiological concentrations that are well in excess of those of progesterone itself (peak concentrations of 30 ng/mL for allopregnanolone and 60 ng/mL for pregnanolone versus 12 ng/mL for progesterone at 4 hours after a single 200-mg oral dose of progesterone). In one study, a single 200-mg oral dose of progesterone resulted in peak levels of 20α-dihydroprogesterone of around 1 ng/mL after 2 hours. The percentage constitutions of progesterone and its metabolites as reflected in serum levels have been determined for a single 100 mg dose of oral or vaginal progesterone.
=== Legal status === The US Food and Drug Administration (FDA) approved tranexamic acid oral tablets (brand name Lysteda) for the treatment of heavy menstrual bleeding in November 2009. In March 2011, the status of tranexamic acid for the treatment of heavy menstrual bleeding was changed in the UK, from POM (Prescription only Medicines) to P (Pharmacy Medicines) and became available over the counter in UK pharmacies under the brand names of Cyklo-F and Femstrual.
==== Pit closures ==== Heseltine's responsibilities also included Energy, as the separate Energy ministry was abolished. Electricity companies now decided on their own contracts, rather than being obliged by the government to choose British coal. With plans being made for the privatisation of British Coal, on 13 October 1992 Heseltine and British Coal both separately announced that 31 of British Coal's 50 pits were to close, with the loss of 30,000 jobs. Most of the detailed work had been done by the minister of state Tim Eggar. Many of the mines in Nottinghamshire that had continued working during the 1984–1985 strike were to close. Although this policy was seen by the Nottinghamshire miners as a betrayal, there was hardly any organised resistance to the programme. The government stated that since the pits were losing money they could be sustained only through unjustifiable government subsidies. Mine supporters pointed to the mines' high productivity rates and to the fact that their monetary losses were due to the large subsidies that other European nations were giving to their coal industries. An early leak had seen little reaction but Heseltine was taken aback by the public anger. Over 100 pits had closed since the 1984–1985 strike. The closures were to be rushed because the Treasury, under pressure from Major, had agreed to make money for generous redundancy settlements available only in the 1992–1993 fiscal year.
Sources: en.wikipedia.org
It should first equilibrate to room temperature in a sealed container to prevent condensation on the cold contents. Opening too soon can introduce moisture and reduce stability, and the waiting period depends on vial size and packaging.
Hydrophobic peptides may require buffers, organic cosolvents, or a stepwise solvent approach. Small amounts of acetonitrile, methanol, or dimethyl sulfoxide are sometimes used, followed by dilution into aqueous buffer. The exact solvent system should be tested for the specific sequence.
Single-use aliquots limit freeze-thaw cycling, which can cause aggregation, precipitation, or loss of activity. They also reduce repeated opening of the same container and lower contamination risk. Labeling each aliquot supports traceability and consistent use.
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.