If you have been reading about size-exclusion chromatography and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Updated 2025-09-03. Numbers and descriptions here follow the published literature rather than marketing material.
Storage stability depends on moisture, temperature, and packaging. Dry powders with low water activity resist microbial growth, but they can still absorb water, develop off-colors through Maillard reactions, or oxidize residual lipids. Sealed containers kept in a cool, dry place are standard. Stability studies typically monitor moisture, solubility, color, peptide size, and microbial counts over months. Established practice favors low humidity and moderate temperatures. How brief excursions above recommended conditions affect peptide profiles and sensory qualities is less predictable and may depend on the specific product matrix.
Laboratories characterize hydrolyzed whey protein with several complementary assays. Total nitrogen methods, such as Kjeldahl or Dumas, estimate protein content using a dairy conversion factor. Free amino group assays, including TNBS and OPA, track the extent of peptide-bond cleavage. Size-exclusion chromatography and reversed-phase HPLC reveal peptide size distributions and hydrophobicity. Mass spectrometry can identify specific peptides, while amino acid analysis quantifies individual residues. No single test captures every relevant property, so results are usually interpreted together with process records and specification limits.
Quality control checks identity, composition, and contaminants. Moisture, ash, fat, and carbohydrate are measured by standard methods, and microbiological limits are set for total counts, coliforms, and specific pathogens. Heavy metals and pesticide residues may be monitored depending on market requirements. Adulteration with intact whey protein or individual amino acids is possible, so peptide fingerprints and free amino acid profiles can help verify authenticity. Regulatory frameworks vary: some countries treat hydrolyzed whey as a conventional dairy ingredient, while infant formula uses face additional compositional rules. Which marker peptides best confirm source and processing remains an open analytical question.
Regulatory and labeling frameworks vary by country. In the United States, whey protein hydrolysate may be regulated as a food ingredient or a dietary supplement ingredient depending on intended use. In the European Union, it falls under general food law, with additional rules for infant formula and foods for special medical purposes. A claim of hypoallergenicity is not established by hydrolysis alone and generally requires clinical evidence. Open questions remain about how degree of hydrolysis relates to bitterness, nitrogen absorption, and residual allergenicity across different products and processing methods.
Quality control for whey protein hydrolysate combines compositional and molecular tests. Protein content is measured by Kjeldahl or Dumas nitrogen determination. Moisture, ash, fat, and lactose are checked with standard food methods. The degree of hydrolysis is estimated by TNBS, OPA, or pH-stat procedures that quantify free amino groups or released protons. Molecular weight distribution is examined by size-exclusion chromatography or SDS-PAGE. These tests describe average peptide size rather than exact peptide sequences, and results depend on standards and calibration.
Advanced peptide profiling uses liquid chromatography coupled with mass spectrometry to identify fragments and assess batch consistency. Amino acid analysis after acid hydrolysis quantifies the building blocks and can reveal deviations from expected composition. Residual enzyme activity may be monitored in products where active enzymes are undesirable. Allergen tests often use immunoassays for beta-lactoglobulin, but hydrolysis can reduce or alter epitope recognition, so negative results do not prove absence of allergenic potential. Physical tests include particle size, bulk density, and reconstitution behavior.
| Property | Value | Notes |
|---|---|---|
| Total protein | 70–85% dry basis | Kjeldahl or Dumas with factor 6.38. |
| Peptide-bond cleavage | 5–35% | TNBS or OPA; assay-dependent. |
| Peptide size | Mostly 0.2–10 kDa | Size-exclusion chromatography. |
| Water activity | Below 0.6 | Limits microbial growth in powder. |
| Shelf life | 18–24 months | Sealed, cool, dry storage; product-specific. |
Stability depends on moisture, temperature, oxygen, and packaging. Powdered hydrolysate generally requires cool, dry storage and protection from humidity because peptides can absorb water and undergo Maillard reactions with residual lactose. Higher temperatures can increase bitterness, discoloration, and loss of solubility over time, while liquid hydrolysate formats are more perishable and may need refrigeration or preservatives. Shelf-life studies typically monitor moisture, color, pH, protein solubility, and microbial counts. Exact stability limits vary by peptide profile, packaging, and water activity, so general rules should be treated as approximate.
Industrial production begins with whey protein concentrate or isolate dispersed in water. Selected proteases, such as trypsin, pepsin, or microbial enzymes, are added under controlled pH and temperature. Hydrolysis continues until a target hydrolysis level is reached, after which heat or pH adjustment inactivates the enzyme. Ultrafiltration, diafiltration, and ion exchange may remove larger peptides, salts, or residual lactose. The liquid is then concentrated and spray-dried into powder. Processing choices influence peptide size, bitterness, mineral content, and microbial quality.
Analytical control focuses on protein content, hydrolysis extent, molecular weight distribution, and residual intact protein. Kjeldahl or Dumas methods measure total nitrogen, while size-exclusion chromatography or mass spectrometry estimates peptide profiles. Sodium dodecyl sulfate polyacrylamide gel electrophoresis can show remaining intact proteins, though small peptides may not resolve. Enzyme-linked immunosorbent assays are used to assess residual allergenic proteins in some contexts. Because no single method captures all relevant features, manufacturers combine several assays and report values against internal specifications.
Dry hydrolysate powders are generally stable when kept cool, dry, and sealed, while moisture uptake can cause caking, Maillard browning, and loss of solubility. Higher temperatures accelerate these changes and may alter flavor. Recommended storage conditions often fall between 15 and 25 degrees Celsius with relative humidity below 60 percent. Once reconstituted, liquid hydrolysate solutions support microbial growth and may develop bitterness or haze over time. Packaging in moisture-barrier containers with desiccants helps maintain quality during transport and warehouse storage.
Quality control for hydrolysate ingredients focuses on identity, purity, and consistency, with specifications that may include total protein, hydrolysis level, molecular weight distribution, microbiological limits, heavy metals, and allergen labeling. In some jurisdictions, partially and extensively hydrolyzed formulas are regulated as foods for special dietary uses or as infant formula ingredients. Regulatory status varies by country and intended use. Documentation such as certificates of analysis, safety data sheets, and method validation records supports traceability. Open questions remain about standardizing hydrolysis measurements across suppliers and laboratories.
Testing hydrolysate powders typically begins with proximate analysis for moisture, ash, fat, and total nitrogen. Protein content is calculated from nitrogen using a conversion factor, most often Kjeldahl or Dumas combustion. Peptide size distribution is assessed by size-exclusion chromatography, reversed-phase HPLC, or mass spectrometry. Sodium dodecyl sulfate polyacrylamide gel electrophoresis can show residual intact protein bands. Free amino groups may be quantified by colorimetric assays to estimate cleavage extent, though different methods and laboratories are not always directly comparable.
Stability and storage practices affect measured quality over time. Hydrolysate powders are hygroscopic and can absorb moisture, leading to caking, Maillard browning, and reduced solubility. Cool, dry storage in sealed containers limits these changes, while high humidity and warm temperatures accelerate them. Microbiological testing for total aerobic counts, yeasts, molds, and specified pathogens is typical for food ingredients. Regulatory status varies by country; in many jurisdictions hydrolyzed whey protein is regulated as a food ingredient rather than a drug, and claims about reduced allergenicity require specific substantiation.
Quality control for whey protein hydrolysate begins with verifying protein content, moisture, ash, and fat using standard food analysis methods. Total nitrogen by Kjeldahl or Dumas combustion gives an estimate of protein, often calculated with a dairy-specific conversion factor. Amino acid analysis after acid hydrolysis quantifies individual residues but destroys tryptophan and may convert glutamine and asparagine. The extent of peptide bond cleavage is usually estimated by measuring free amino groups, soluble nitrogen, or trichloroacetic acid-soluble peptides. These tests are operationally defined and can give different results across laboratories.
Storage stability depends on moisture, temperature, oxygen, and packaging, and hydrolysates are hygroscopic and can cake when exposed to humid air. Maillard reactions between peptides and residual lactose can cause browning and flavor changes during warm storage, while lipid oxidation may develop if residual fat is present. Cool, dry conditions and sealed containers slow these reactions. Shelf-life studies typically monitor moisture, color, solubility, molecular weight profile, and microbial counts over time. Accelerated tests estimate stability, but real-time data remain the reference for shelf-life assignment.
Regulatory status differs by country and intended use. In many jurisdictions, whey protein hydrolysate is regulated as a food ingredient, while specific infant formula or medical food uses may require additional review. Labeling rules govern protein content claims, allergen statements, and terms such as partially hydrolyzed or extensively hydrolyzed. Analytical methods for degree of hydrolysis are not fully standardized, so values can depend on the assay. This variability makes direct comparison between products difficult unless the method and reference material are stated.
In humans, the total female diploid nuclear genome per cell extends for 6.37 Gigabase pairs (Gbp), is 208.23 cm long and weighs 6.51 picograms (pg). Male values are 6.27 Gbp, 205.00 cm, 6.41 pg. Each DNA polymer can contain hundreds of millions of nucleotides, such as in chromosome 1. Chromosome 1 is the largest human chromosome with approximately 220 million base pairs, and would be 85 mm long if straightened. In eukaryotes, in addition to nuclear DNA, there is also mitochondrial DNA (mtDNA) which encodes certain proteins used by the mitochondria. The mtDNA is usually relatively small in comparison to the nuclear DNA. For example, the human mitochondrial DNA forms closed circular molecules, each of which contains 16,569 DNA base pairs, with each such molecule normally containing a full set of the mitochondrial genes. Each human mitochondrion contains, on average, approximately 5 such mtDNA molecules. Each human cell contains approximately 100 mitochondria, giving a total number of mtDNA molecules per human cell of approximately 500. However, the amount of mitochondria per cell also varies by cell type, and an egg cell can contain 100,000 mitochondria, corresponding to up to 1,500,000 copies of the mitochondrial genome (constituting up to 90% of the DNA of the cell).
He suggests that hindsight criticism of the early publications should be mitigated by the then nascent state of radiochemistry: highlighting the prudence of Debierne's claims in the original papers, he notes that nobody can contend that Debierne's substance did not contain actinium. Debierne, who is now considered by the vast majority of historians as the discoverer, lost interest in the element and left the topic. Giesel, on the other hand, can rightfully be credited with the first preparation of radiochemically pure actinium and with the identification of its atomic number 89. The name actinium originates from the Ancient Greek aktis, aktinos (ακτίς, ακτίνος), meaning beam or ray. Its symbol Ac is also used in abbreviations of other compounds that have nothing to do with actinium, such as acetyl, acetate and sometimes acetaldehyde.
Hazard research is published: the annual Global Carbon Budget study finds fossil CO2 emissions are still rising when if they stayed the same, the 50% likelihood to limit global warming to 1.5 °C would be exceeded around 2031 (5 Dec), the genetic testing company 23andMe confirms that the genetic privacy of around 7 million customers has been violated in the 23andMe data leak (5 Dec), a study using plasma proteomics aging clocks suggests nearly 20% of the population may show strongly accelerated age in one of 11 major organs, which it links to higher mortality risk (6 Dec), cumulative loneliness in mid-to-later life, a growing public health concern, is confirmed as potential substantial excess mortality risk factor with U.S. data (11 Dec), news outlets report on a study (13 Oct) finding ~82% of fish samples from two Michigan watersheds exceed daily consumption limit for adults of total PFOS (12 Dec), a study robustifies the link between women's preconception exposure to phthalates and lower fecundability, changes in reproductive hormones, and increased inflammation using EAGeR trial data (13 Dec), a study of meal timing using French NutriNet-Santé data indicates longer nighttime fasting periods may be superior to breakfast skipping in intermittent fasting (14 Dec), one of the first horizon scan risk screening studies by region on invasive species threats identifies 40 high-risk potential invaders to Florida (14 Dec).
Soy sauce (sometimes called soya sauce in British English) is a liquid condiment of Chinese origin, traditionally made from a fermented paste of soybeans, roasted grain, brine, and Aspergillus oryzae or Aspergillus sojae molds (kōji). It is recognized for its saltiness and pronounced umami taste. Soy sauce was created in its current form about 2,200 years ago during the Western Han dynasty of ancient China. Since then, it has become an important ingredient in East and Southeast Asian cooking as well as a condiment worldwide.
== See also == Mr. Holland's Opus, a 1995 film starring Richard Dreyfuss Magnum opus (disambiguation) Opera (disambiguation) (plural form of opus) Opus Dei (disambiguation) All pages with titles beginning with Opus All pages with titles containing Opus
Sources: en.wikipedia.org
The club was founded by members of the Royal Agricultural Society, the Melbourne Hunt Club and the Victorian Woolbrokers. The Essendon Football Club is thought to have been formed in 1872 at a meeting in the home of a well-known brewery family, the McCrackens, whose Ascot Vale property hosted a team of local junior players. Robert McCracken (1813–1885), the owner of several city hotels, was the founder and first president of the Essendon Football Club, and his son, Alex McCracken, its first secretary. Alex later became president of the newly formed VFL. Alex's cousin Collier McCracken, who had already played with Melbourne, was the team's first captain. The club played its first recorded match against the Carlton Second Twenty (the reserves) on 7 June 1873, with Essendon winning by one goal. Essendon played 13 matches in its first season, winning seven, with four draws and losing two. The club was one of the inaugural junior members of the Victorian Football Association (VFA) in 1877, and it began competing as a senior club from the 1878 season. During its early years in the Association, Essendon played its home matches at Flemington Hill, but it moved to the East Melbourne Cricket Ground in 1881. In 1878, at Flemington Hill, Essendon played its first match on what would be considered by modern standards to be a full-sized field. In 1879, Essendon played Melbourne in one of the earliest night matches recorded when the ball was painted white.
Bupropion is an aminoketone that belongs to the class of substituted cathinones and the more general class of substituted phenethylamines. It is also known structurally as 3-chloro-N-tert-butyl-β-keto-α-methylphenethylamine, 3-chloro-N-tert-butyl-β-ketoamphetamine, or 3-chloro-N-tert-butylcathinone. The clinically used bupropion is racemic, which is a mixture of two enantiomers: S-bupropion and R-bupropion. Although the optical isomers of bupropion can be separated, they rapidly racemize under physiological conditions. Bupropion is a small-molecule compound with the molecular formula C13H18ClNO and a molecular weight of 239.74 g/mol. It is a highly lipophilic compound, with an experimental log P of 3.6. Pharmaceutically, bupropion is used mainly as the hydrochloride salt but also to a lesser extent as the hydrobromide salt. There have been reported cases of false-positive urine amphetamine tests in persons taking bupropion.
The two substrates of this enzyme are D-gluconic acid and oxidised nicotinamide adenine dinucleotide (NAD+). Its products are 5-oxo-D-gluconic acid, reduced NADH, and a proton. The enzyme can use nicotinamide adenine dinucleotide phosphate as an alternative cofactor. This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-OH group of donor with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is D-gluconate:NAD(P)+ 5-oxidoreductase. Other names in common use include 5-keto-D-gluconate 5-reductase, 5-keto-D-gluconate 5-reductase, 5-ketogluconate 5-reductase, 5-ketogluconate reductase, and 5-keto-D-gluconate reductase.
== Localization and export == MBP is exported into the periplasmic space of E. coli. The NH2-terminal extension of MBP, also termed signal peptide, has two roles: (i) it slows down folding of the newly synthesized polypeptide, and (ii) it directs this polypeptide to the membrane and SecYEG translocon. Once folded, the precursor can no longer enter the translocation pathway. The introduction of a charged amino-acid residue or a proline residue within the hydrophobic core of the signal peptide is sufficient to block export. The defective exports of the mutant MBPs are consistent with the alpha-helical conformation and hydrophobic interactions of the signal peptide in its interaction with the translocon motor protein SecA.
Another application of CE in forensics is ink analysis, where the analysis of inkjet printing inks is becoming more necessary due to increasingly frequent counterfeiting of documents printed by inkjet printers. The chemical composition of inks provides very important information in cases of fraudulent documents and counterfeit banknotes. Micellar electrophoretic capillary chromatography (MECC) has been developed and applied to the analysis of inks extracted from paper. Due to its high resolving power relative to inks containing several chemically similar substances, differences between inks from the same manufacturer can also be distinguished. This makes it suitable for evaluating the origin of documents based on the chemical composition of inks. It is worth noting that because of the possible compatibility of the same cartridge with different printer models, the differentiation of inks on the basis of their MECC electrophoretic profiles is a more reliable method for the determination of the ink cartridge of origin (its producer and cartridge number) rather than the printer model of origin. A specialized type of CE, affinity capillary electrophoresis (ACE), utilizes intermolecular binding interactions to understand protein-ligand interactions. Pharmaceutical companies use ACE for a multitude of reasons, with one of the main ones being the association/binding constants for drugs and ligands or drugs and certain vehicle systems like micelles. It is a widely used technique because of its simplicity, rapid results, and low analyte usage.
Sources: en.wikipedia.org
MiaB introduces a methylthio group to the isopentenylated A37 derivatives in the tRNA of S. Typhimurium and E. coli by utilizing one SAM molecule to generate 5'-dAdo radical to activate the substrate and a second SAM to donate a sulfur atom to the substrate. RimO is responsible for post-translational modification of Asp88 of the ribosomal protein S12 in E. coli. The crystal structure sheds light on the mechanistic action of RimO. The enzyme catalyzes pentasulfide bridge formation linking two Fe-S clusters to allow for sulfur insertion to the substrate. eMtaB is the designated methylthiotransferase in eukaryotic and archaeal cells. eMtaB catalyzes the methylthiolation of tRNA at position 37 on N6-threonylcarbamoyladenosine. A bacterial homologue of eMtaB, YqeV has been reported and suggested to function similarly to MiaB and RimO.
Ligamentous laxity or ligament laxity can appear in a variety of ways and levels of severity. In most people, ligaments (which are the tissues that connect bones to each other) are naturally tight in such a way that the joints are restricted to 'normal' ranges of motion. This creates normal joint stability. If muscular control does not compensate for ligamentous laxity, joint instability may result. The trait is almost certainly hereditary, and is usually something the affected person would just be aware of, rather than a serious medical condition. However, if there is widespread laxity of other connective tissue, then this may be a sign of Ehlers–Danlos syndrome, Down syndrome, Klippel–Feil syndrome, juvenile idiopathic arthritis, Larsen syndrome, Marfan syndrome, osteogenesis imperfecta, and other medical conditions. Ligamentous laxity may also result from injury, such as from a vehicle accident. It can result from whiplash and be overlooked for years by doctors who are not looking for it, despite the chronic pain that accompanies the resultant spinal instability. Ligamentous laxity will show up on an upright magnetic resonance imaging (MRI), the only kind of MRI that will show soft tissue damage. It can only be inferred from a digital motion x-ray.
After starting a collaboration on heart applications with Robert Weiss at Johns Hopkins, Paul returned to Johns Hopkins University in 1994, as Professor and Director of the MR Research Division. He worked on the application of MRS to measure cardiac energy metabolism in the healthy and ischemic human heart, finding that creatine kinase energy supply was compromised in heart failure, that it declined in relation to cardiac mechanical work and that it was an independent predictor of cardiac events and death. More recent work showed that a neural network based on cardiac CK metabolic parameters alone could differentiate a number of different types of cardiac disease and severity with potentially clinically useful accuracy. Paul has also worked on developing interventional MRI technology, specifically, tiny MRI detector coils that can be built into catheters to perform high resolution imaging of vessel wall and surrounding tissues; accelerated to perform real-time high resolution 'MRI endoscopy'; and potentially combined with extra-vascular therapy delivery. The earlier work led to the founding of the SurgiVision Inc start-up noted at top, and later, the development of MRI-safe implantable lead technology (licensed and sold as Avista™ by Boston Scientific Inc).
=== Jiffy === In computing, the jiffy is the duration of one tick of the system timer interrupt. Typically, this time is 0.01 seconds, though in some earlier systems (such as the Commodore 8-bit machines) the jiffy was defined as 1⁄60 of a second, roughly equal to the vertical refresh period (i.e. the field rate) on NTSC video hardware (and the period of AC electric power in North America).
Sources: en.wikipedia.org
Common laboratory methods measure free amino groups with TNBS or OPA reagents. The result is converted to a percentage using a reference standard and a defined protocol. Values are method-dependent, so comparisons require the same assay conditions.
Size-exclusion chromatography separates peptides by molecular size, while reversed-phase HPLC separates them by hydrophobicity. Mass spectrometry provides mass and sequence information for individual peptides. Together these methods give a more complete picture than any single technique.
Yes, free amino group assays and peptide profiles usually differ between the two. However, blends and partially hydrolyzed samples can make interpretation difficult. Authenticity testing often combines several methods rather than relying on one marker.
It is often estimated by TNBS, OPA, or pH-stat methods that quantify free amino groups or released protons. Values depend on assay conditions, protein standard, and calculation method. No single universal protocol exists for all products.