DAC is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Updated 2025-11-11. Numbers and descriptions here follow the published literature rather than marketing material.
CJC-1295 is the name used for a synthetic peptide modeled on growth hormone-releasing hormone, the hypothalamic signal that prompts the pituitary to release growth hormone. The compound was described by a Canadian drug discovery company in the mid-2000s as a long-acting research tool. Two closely related molecules share the name in practice: one carries a drug affinity complex, or DAC, group, and one does not. The distinction matters because the two behave differently in circulation.
The peptide backbone corresponds to GRF(1-29), the first 29 residues of native growth hormone-releasing hormone, which retains most of the receptor-activating activity of the full-length molecule. Four substitutions distinguish the analog from the natural sequence: D-alanine at position 2, glutamine at position 8, alanine at position 15, and leucine at position 27. These changes slow cleavage by dipeptidyl peptidase IV, the enzyme that degrades native hormone in plasma within minutes. The outcome is improved enzymatic stability combined with a still brief residence time when no additional modification is present.
Lyophilized material is generally stable for extended periods when held at minus twenty degrees Celsius or below and protected from moisture and light. In solution the peptide is more labile; bond hydrolysis, aggregation and oxidation of susceptible residues all proceed faster at ambient temperature. Repeated freeze and thaw cycles should be avoided because they promote clumping and loss of soluble material. The conjugated variant adds a further consideration, since the maleimide group can hydrolyze in aqueous buffer and lose its ability to react with albumin.
Laboratory handling centers on minimizing exposure to water, heat and oxygen before use. Working solutions are typically prepared in sterile water or a mild buffer, and any residual particulate matter is removed by filtration. When the powder dissolves slowly, a small proportion of acetonitrile or dilute acetic acid is sometimes added as a co-solvent. Containers are kept sealed and desiccated between uses. Records of lot number, reconstitution date and storage conditions support later comparison of results across experiments.
Identity and purity are established with reversed phase high performance liquid chromatography coupled to mass spectrometry. The chromatographic step separates the target peptide from truncated sequences and deletion products, while the mass measurement confirms the expected molecular weight to within a fraction of a dalton. Because the two common variants differ by the presence of the linker, mass alone can distinguish them in the unconjugated state. Amino acid analysis and peptide mapping are used when sequence level confirmation is required.
| Property | Value | Notes |
|---|---|---|
| Molecular class | Synthetic peptide | GHRH analog, not a steroid |
| Backbone length | 29 amino acids | Based on GRF(1-29) |
| Substitutions | Four positions | D-Ala2, Gln8, Ala15, Leu27 |
| Appearance | White to off-white powder | Typical lyophilized research material |
| Common synonyms | Modified GRF(1-29) | Usage varies between sources |
Characterization of this peptide relies on a small set of routine techniques. Reversed-phase high-performance liquid chromatography separates the target from truncated or oxidized by-products and yields a purity estimate when paired with ultraviolet detection near 214 nanometers. Mass spectrometry, either electrospray coupled to liquid chromatography or matrix-assisted laser desorption, confirms that the observed mass matches the value calculated for the expected sequence. Amino acid analysis, and enzymatic digestion followed by fragment mapping, are used when the sequence itself rather than the mass requires verification.
Stability depends heavily on physical state. A lyophilized powder kept dry, desiccated, and shielded from light typically holds its integrity for months to years at minus twenty degrees Celsius, and longer at minus eighty. Once dissolved, the peptide becomes far more vulnerable, since peptide bond hydrolysis, oxidation of susceptible residues, and aggregation all proceed faster in solution. Buffers near neutral pH are generally gentler than strongly acidic or alkaline conditions. Repeated freeze-thaw cycles and exposure to air-liquid interfaces during vigorous mixing cause losses that are easy to overlook.
Verification matters because research peptides vary widely in quality. A certificate of analysis is only as reliable as the method behind it, and a single chromatographic trace reveals little about counter-ions, residual solvents, or water content. Independent laboratories commonly pair mass confirmation with chromatographic purity and, where relevant, quantify water along with acetate or trifluoroacetate content. Reported purity figures are not standardized across suppliers, so a stated value such as ninety-eight percent is not directly comparable unless the analytical method, column, and detection wavelength accompany it.
Purity is most often assessed by reversed-phase high-performance liquid chromatography, reported as a percentage of total peak area. Identity is confirmed by mass spectrometry, which yields a molecular ion consistent with the expected sequence. Amino acid analysis and peptide mapping provide additional characterization. Reported purity values are method-dependent, so figures from different laboratories are not always directly comparable without details of column, gradient, and detection wavelength.
Peptide degradation proceeds mainly through hydrolysis, oxidation of methionine, and deamidation of asparagine or glutamine residues. The maleimide group on the albumin-binding variant can also react with thiols or hydrolyze in aqueous media. Because these pathways accelerate with temperature and pH extremes, handling conditions strongly influence measured stability. Stability data in the public literature are limited and often generated under differing conditions, so general statements about shelf life should be read as approximate.
Research material is normally supplied as a freeze-dried powder in sealed vials. In that state the peptide is comparatively robust, but prolonged exposure to warmth, moisture, or light accelerates degradation. Storage at minus twenty degrees Celsius or lower, with desiccant and protection from light, is the commonly described practice. Vials should be allowed to reach room temperature before opening to limit condensation on the powder. Moisture uptake during handling is a recognized source of variability in later measurements.
CJC-1295 is a synthetic peptide analog of growth hormone-releasing hormone, constructed on the 29-amino-acid fragment designated GRF(1-29). The name began as an internal development code during the 1990s and later spread through research supply catalogs and discussion forums. The molecule does not occur in nature; its sequence is engineered rather than isolated from tissue. Two related compounds are sold under this single label, and they differ by one appended chemical group that strongly influences how long the peptide remains in circulation.
The dividing feature between the two forms is a maleimide-based drug affinity complex, abbreviated DAC. In the DAC-bearing version, a linker attaches the peptide to serum albumin after administration, and that association slows removal from plasma. The version lacking DAC appears in catalogs as MOD GRF(1-29) or tetrasubstituted GRF(1-29). Because informal writing treats both as one item, comparisons drawn from such sources routinely blend measurements taken from two molecules with substantially different behavior.
He ruled that only Whitehall could determine what constituted the maintenance of "law and order" in Rhodesia, and that the Rhodesian emergency measures were unlawful as they had been formalised by the Officer Administering the Government, a post-UDI figure who was, in British eyes, unconstitutional. Reid concluded that Madzimbamuto was illegally detained. Harry Davies, one of the Rhodesian judges, announced on 8 August that the Rhodesian courts would not consider this ruling binding as they no longer accepted the Privy Council as part of the Rhodesian judicial hierarchy. Justice J. R. Dendy Young resigned in protest at Davies' ruling on 12 August and four days later was sworn in as Chief Justice of Botswana. The Rhodesian High Court granted full de jure recognition to the post-UDI government on 13 September 1968, while rejecting the appeals of 32 black Rhodesians who had been a month earlier convicted of terrorist offences and sentenced to death. Beadle declared that while he believed the Rhodesian judiciary should respect rulings of the Privy Council "so far as possible", the judgement of 23 July had made it legally impossible for Rhodesian judges to continue under the 1961 constitution. He asserted that the court therefore faced a choice between the 1965 constitution and a legal vacuum, the latter of which he felt he could not endorse.
=== Nitrogen relationships === Xanthoria parietina is highly adaptable to nitrogen-rich environments, with thalli containing between 11 and 43 milligrams per gram of nitrogen (dry weight), a broader range than most other green algal lichens. The species maintains metabolic balance by shifting resource allocation between its fungal and algal partners, directing more resources to its photobiont under high nitrogen conditions. Unlike nitrogen-sensitive species, X. parietina sustains consistent growth patterns regardless of nitrogen concentration, allowing it to thrive in agricultural areas and urban centers. his adaptation to high nitrogen environments explains its frequent association with eutrophication and its common presence near farmland and livestock facilities. Transplant experiments near a pig farm in Denmark further demonstrated its nitrogen accumulation ability. Lichen thalli exposed to high ammonia levels rapidly increased their nitrogen content, reaching approximately 2.1% within a month, whereas samples positioned 300 meters away maintained lower levels (around 1.6%). In situ samples collected along a transect exhibited a strong linear correlation between thallus nitrogen content and the logarithm of ambient ammonia concentrations. Additional research suggests that X. parietina's nitrogen tolerance may be linked to osmotic adaptations rather than a direct nitrogen preference. It is primarily halotolerant and xerophytic, with cell osmotic values significantly higher than those of non-nitrophytic species.
In response, Conservative leader Kemi Badenoch accuses Farage of "manipulating" the publish by publishing "fake" figures and using an automated ticker to falsely inflate membership numbers. The following day, Farage threatens to "take some kind of action in the next couple of days", while the Reform website says the membership figure has increased to above 143,000. 27 December – Former Conservative Justice Secretary David Gauke, who is leading a review into sentencing and prison overcrowding, calls for greater use of open prisons in order to ease the pressure on closed category prisons. 29 December – Reform UK says it has notched up a further 20,000 members since the Kemi Badenoch row, reaching 150,000 members. Conservative Party allies of Kemi Badenoch reject claims she asked GB News to reduce Nigel Farage's airtime on the channel. 30 December – The King and the Prime Minister pay tribute to Jimmy Carter, following the former US president's death at the age of 100. Conor Murphy, a minister in the Northern Ireland Executive, announces he will contest the 2025 Seanad election in the Republic of Ireland for Sinn Féin, saying he will resign as a member of the Stormont Assembly if successful. 2025 New Year Honours: Those from the world of politics recognised in the New Year Honours include Sadiq Khan, Nick Gibb and Andy Street, who receive knighthoods, and Emily Thornberry, who receives a damehood.
Polonium is a radioactive element that exists in two metallic allotropes. The alpha form is the only known example of a simple cubic crystal structure in a single atom basis at STP (space group Pm3m, no. 221). The unit cell has an edge length of 335.2 picometers; the beta form is rhombohedral. The structure of polonium has been characterized by X-ray diffraction and electron diffraction. 210Po has the ability to become airborne with ease: if a sample is heated in air to 55 °C (131 °F), 50% of it is vaporized in 45 hours to form diatomic Po2 molecules, even though the melting point of polonium is 254 °C (489 °F) and its boiling point is 962 °C (1,764 °F). More than one hypothesis exists for how polonium does this; one suggestion is that small clusters of polonium atoms are spalled off by the alpha decay.
Sources: en.wikipedia.org
== History == Aspartame was discovered by accident in December 1965 by James M. Schlatter, a chemist working for G.D. Searle & Company in Skokie, Illinois. Schlatter had synthesized aspartame as an intermediate step in generating a tetrapeptide of the hormone gastrin, for use in assessing an anti-ulcer drug candidate. He discovered its sweet taste when he licked his finger, which had become contaminated with aspartame, to lift up a piece of paper. Torunn Atteraas Garin participated in the development of aspartame as an artificial sweetener. In 1975, prompted by issues regarding Flagyl and Aldactone, an FDA task force team reviewed 25 studies submitted by the manufacturer, including 11 on aspartame. The team reported "serious deficiencies in Searle's operations and practices". The FDA sought to authenticate 15 of the submitted studies against the supporting data. In 1979, the Center for Food Safety and Applied Nutrition (CFSAN) concluded, since many problems with the aspartame studies were minor and did not affect the conclusions, the studies could be used to assess aspartame's safety. In 1980, the FDA convened a Public Board of Inquiry (PBOI) consisting of independent advisors charged with examining the purported relationship between aspartame and brain cancer. The PBOI concluded aspartame does not cause brain damage, but it recommended against approving aspartame at that time, citing unanswered questions about cancer in laboratory rats. In 1983, the FDA approved aspartame for use in carbonated beverages and for use in other beverages, baked goods, and confections in 1993.
== External links == History of Mass Spectrometry - Pioneers - University of New South Wales Sydney Five Mass Spectrometry Nobel Prize Pioneers - Bristol University History of Mass Spectrometry - Scripps Institute
In Lao cuisine, Lao coriander is used extensively in traditional Lao dishes such as 'mok pa' (steamed fish in banana leaf) and several coconut milk curries that contain fish or prawns. In China dill is called colloquially, 'huíxiāng' (茴香, perfume of Hui people), or more properly 'shíluó' (莳萝/蒔蘿). It is a common filling in 'baozi', 'jiaozi' and 'xianbing' and may be used as vegetarian with rice vermicelli, or combined with either meat or eggs. Vegetarian dill baozi are a common part of a Beijing breakfast. In baozi and xianbing, it often is interchangeable with non-bulbing fennel and the term 茴香 also may refer to fennel, similarly to caraway and coriander leaf, sharing a name in Chinese as well. Dill also may be stir fried as a potherb, often with egg, in the same manner as Chinese chives. In Northern China, Beijing, Inner-Mongolia, Ningxia, Gansu, and Xinjiang, dill seeds commonly are called 'zīrán' (孜然), but also 'kūmíng' (枯茗), 'kūmíngzi' (枯茗子), 'shíluózi' (莳萝子/蒔蘿子), 'xiǎohuíxiāngzi' (小茴香子) and are used with pepper for lamb meat. In the whole of China, 'yángchuàn' (羊串) or 'yángròu chuàn' (羊肉串), lamb brochette, a speciality from Uyghurs, uses cumin and pepper. In Cantonese-speaking regions such as Hong Kong and Macau, the leaves are more colloquially known as 刁草 (diu1 cou2), a partial calque of the English 'dillweed'; 'dill' transliterated into the otherwise unrelated 刁 diu1 and 'weed' translated as 草 cou2. In Taiwan, it is also commonly used as a filling in steamed buns (baozi) and dumplings (jiaozi). In Vietnam, the use of dill in cooking is regional.
Sources: en.wikipedia.org
== Uses == Hydroquinone has a variety of uses principally associated with its action as a reducing agent that is soluble in water. It is a major component in most black and white photographic developers for film and paper, where, with the compound metol, it reduces silver halides to elemental silver. There are various other uses associated with its reducing power. As a polymerisation inhibitor, exploiting its antioxidant properties, hydroquinone prevents polymerization of acrylic acid, methyl methacrylate, cyanoacrylate, and other monomers that are susceptible to radical-initiated polymerization. By acting as a free radical scavenger, hydroquinone serves to prolong the shelf life of light-sensitive resins such as preceramic polymers. Hydroquinone can lose a hydrogen cation from both hydroxyl groups to form a diphenolate ion. The disodium diphenolate salt of hydroquinone is used as an alternating comonomer unit in the production of the polymer PEEK.
== Further reading == Bright, M.; Plum, C.; Riavitz, L. A.; Nikolov, N.; Martínez Arbizu, P.; Cordes, E. E.; Gollner, S. (2010). "Epizooic metazoan meiobenthos associated with tubeworm and mussel aggregations from cold seeps of the Northern Gulf of Mexico". Deep-Sea Research Part II: Topical Studies in Oceanography. 57 (21–23): 1982–1989. Bibcode:2010DSRII..57.1982B. doi:10.1016/j.dsr2.2010.05.003. PMC 2995211. PMID 21264038. German, C. R.; Ramirez-Llodra, E.; Baker, M. C.; Tyler, P. A.; the ChEss Scientific Steering Committee (2011). "Deep-Water Chemosynthetic Ecosystem Research during the Census of Marine Life Decade and Beyond: A Proposed Deep-Ocean Road Map". PLoS ONE. 6 (8) e23259. Bibcode:2011PLoSO...623259G. doi:10.1371/journal.pone.0023259. PMC 3150416. PMID 21829722. Lloyd, K. G.; Albert, D. B.; Biddle, J. F.; Chanton, J. P.; Pizarro, O.; Teske, A. (2010). "Spatial Structure and Activity of Sedimentary Microbial Communities Underlying a Beggiatoa spp. Mat in a Gulf of Mexico Hydrocarbon Seep". PLoS ONE. 5 (1) e8738. Bibcode:2010PLoSO...5.8738L. doi:10.1371/journal.pone.0008738. PMC 2806916. PMID 20090951. Metaxas, A.; Kelly, N. E. (2010). "Do Larval Supply and Recruitment Vary among Chemosynthetic Environments of the Deep Sea?". PLoS ONE. 5 (7) e11646. Bibcode:2010PLoSO...511646M. doi:10.1371/journal.pone.0011646. PMC 2906503. PMID 20657831. Rodríguez, E.; Daly, M. (2010). "Phylogenetic Relationships among Deep-Sea and Chemosynthetic Sea Anemones: Actinoscyphiidae and Actinostolidae (Actiniaria: Mesomyaria)". PLoS ONE. 5 (6) e10958. Bibcode:2010PLoSO...510958R.
The 1970 census showed that white people still comprised most of Detroit's population. However, by the 1980 census, white people had left at such a high rate that the city had gone from 55 percent to 34 percent white within a decade. The decline was even starker than this suggests, considering that when Detroit's population reached its all-time high in 1950, the city was 83 percent white. Economist Walter E. Williams writes that the decline was sparked by the policies of Mayor Young, who Williams claims discriminated against whites. By contrast, urban affairs experts largely blame federal court decisions that decided against NAACP lawsuits and refused to challenge the legacy of housing and school segregation – particularly the case of Milliken v. Bradley, which was appealed up to the Supreme Court. The District Court in Milliken had initially ruled that it was necessary to actively desegregate Detroit and its suburban communities in one comprehensive program. The city was ordered to submit a "metropolitan" plan that would eventually encompass fifty-four separate school districts, busing Detroit children to suburban schools and suburban children into Detroit. The Supreme Court reversed this in 1974. In his dissent, Justice William O. Douglas argued that the majority's decision perpetuated "restrictive covenants" that "maintained ... black ghettos". Gary Orfield and Susan E.
Sources: en.wikipedia.org
No. It is a laboratory-made analog of growth hormone-releasing hormone. The natural hormone is a 44-residue peptide, while the analog is built on a shorter 29-residue fragment.
The original material included a linker that binds serum albumin. A later variant removed that linker to reduce the duration of action. Catalogs and papers did not consistently adopt separate names, so both remain widely labeled with the same term.
The amino acid sequence and the presence or absence of the linker group. Mass measured by spectrometry gives an independent check that separates the two forms.
The mass difference from the linker is large enough for routine detection by mass spectrometry. The unconjugated form gives a single sharp signal at its expected weight. Material that has already reacted with albumin shows a much higher mass and a broadened chromatographic peak.