DAC linker raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
This page was last updated on 2026-05-13 and is reviewed periodically as new material appears.
Two related forms appear under the CJC-1295 name. The simpler analogue, commonly written as modified GRF(1-29), carries the four substitutions but no additional conjugation. The second form attaches a maleimidopropionic acid linker to a lysine residue, a modification frequently called the drug affinity complex. That linker reacts with the free thiol on serum albumin to form a covalent bond. Because albumin has a long residence time in blood, the conjugated peptide stays in circulation far longer than the unconjugated analogue.
Receptor level activity follows the canonical GHRH pathway. The peptide binds the GHRH receptor, a class B G protein coupled receptor on somatotroph cells of the anterior pituitary. Binding raises intracellular cyclic AMP, which promotes calcium entry and the release of growth hormone into the bloodstream. Because the molecule acts at the same receptor as the endogenous hormone, its effect is superimposed on the natural pulsatile rhythm rather than replacing it. Whether sustained receptor occupation leads to desensitization is not fully settled.
CJC-1295 belongs to a class of synthetic peptides modeled on growth hormone releasing hormone, a forty-four amino acid signal produced by the hypothalamus. The compound is built from the first twenty-nine residues of the natural sequence, with four substitutions introduced at positions 2, 8, 15 and 27. These changes were designed to slow enzymatic breakdown while preserving receptor activation. The result is a peptide that is shorter than native GHRH and considerably more resistant to ordinary clearance pathways in circulation.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Peptide class | Synthetic GHRH analogue | Built on a 29 residue sequence |
| Primary target | GHRH receptor (GHRHR) | Class B G protein coupled receptor |
| Unconjugated half life | Minutes | Limited by protease degradation |
| Key modification | Four residue substitutions | Positions 2, 8, 15 and 27 |
| Common synonym | Modified GRF(1-29) | Usually denotes the form without DAC |
CJC-1295 belongs to a family of synthetic peptides modeled on growth hormone-releasing hormone, the hypothalamic signal that prompts the pituitary to release growth hormone. The compound is built from the first twenty-nine amino acids of the natural human sequence, a fragment that retains full receptor binding capacity. Native growth hormone-releasing hormone is degraded quickly in circulation, so the fragment alone has limited practical value. Early work therefore focused on chemical modifications that preserve receptor binding while slowing enzymatic breakdown. The result is a molecule described in the literature as a long-acting analog of the natural hormone.
Two forms circulate under the CJC-1295 name, and they differ by a single appended group. The version without a drug affinity complex carries four substitutions along the peptide chain, including a D-alanine near the amino terminus and replacements at three other positions. These changes block the enzyme dipeptidyl peptidase IV and remove a methionine residue that is prone to oxidation. The modified fragment is frequently labeled MOD GRF 1-29. Naming conventions are inconsistent across informal sources, which is a common source of confusion.
Two forms circulate in research settings and are frequently confused. One carries the drug affinity complex and is often written as CJC-1295 with DAC; the other lacks that group and is usually called modified GRF(1-29). The two share the same core sequence but differ sharply in how long they persist in blood. Products labelled only as CJC-1295 normally refer to the version carrying the complex. Documentation that omits the distinction leaves the intended molecule ambiguous.
CJC-1295 is a synthetic peptide built as a long-acting analogue of growth hormone-releasing hormone. Its backbone matches the first twenty-nine residues of the natural human hormone, with four amino acid substitutions added to slow enzymatic breakdown. A reactive maleimide group, commonly termed the drug affinity complex, allows the peptide to attach to circulating albumin after administration. That albumin attachment keeps the molecule in the bloodstream for an extended period instead of being cleared within minutes.
The drug affinity complex is a maleimidopropionic acid group attached to a lysine side chain. It reacts with the free thiol of cysteine-34 on circulating albumin, forming a covalent bond. This conjugation keeps the peptide in the bloodstream and shields it from rapid renal filtration and proteolysis. Reported circulation half-lives for the albumin-bound form fall in the range of roughly six to nine days in early human studies.
Binding to GHRH receptors on pituitary somatotroph cells triggers cyclic AMP signaling and stimulates growth hormone synthesis and release. Because the peptide acts upstream of the pituitary, effects are mediated through endogenous growth hormone rather than direct receptor activation in peripheral tissues. Increases in insulin-like growth factor 1 are generally described as a downstream consequence. Most published human exposure data come from small early-stage studies, and the clinical significance of the pharmacokinetic profile remains incompletely characterized.
== Recognition == In 2018, Icon won PharmaTimes Clinical Researcher of the Year. In 2021, Icon was awarded PharmaTimes Clinical Research Company of the Year, and in 2022, won Best Contract Research Organisation (FSP) at the Scrip Awards. In 2025 Icon was recognized in Forbes World's Top Companies for Women, and in TIME World's Best Companies list. In 2026, the company was recognized by TIME's World's Best Companies in Sustainable Growth for the second consecutive year.
The goal of protein design is to find a protein sequence that will fold to a target structure. A protein design algorithm must, thus, search all the conformations of each sequence, with respect to the target fold, and rank sequences according to the lowest-energy conformation of each one, as determined by the protein design energy function. Thus, a typical input to the protein design algorithm is the target fold, the sequence space, the structural flexibility, and the energy function, while the output is one or more sequences that are predicted to fold stably to the target structure. The number of candidate protein sequences, however, grows exponentially with the number of protein residues; for example, there are 20100 protein sequences of length 100. Furthermore, even if amino acid side-chain conformations are limited to a few rotamers (see Structural flexibility), this results in an exponential number of conformations for each sequence. Thus, in our 100 residue protein, and assuming that each amino acid has exactly 10 rotamers, a search algorithm that searches this space will have to search over 200100 protein conformations. The most common energy functions can be decomposed into pairwise terms between rotamers and amino acid types, which casts the problem as a combinatorial one, and powerful optimization algorithms can be used to solve it. In those cases, the total energy of each conformation belonging to each sequence can be formulated as a sum of individual and pairwise terms between residue positions.
== Regulation == Transcriptional regulation of MMP-13 is tightly controlled due to its potent proteolytic capacity. There are several binding domains for various transcription factors including AP-1, PEA-3 and OSE-2 as well as a sequence with homology to a TGF-β inhibitory element (TIE). Moreover, several cytokines and growth factors have been demonstrated to affect Mmp13 gene expression, including parathyroid hormone, IGF-1, TGF-β, hepatocyte growth factor and many inflammatory cytokines such as IL-1α and IL-1β. The upstream regulatory region of the Mmp13 gene contains a number of transcription factor binding sites but it was recently discovered that there is a conserved forkhead response element (FHRE) consensus sequence for FOXO3a in the human, mouse and rat Mmp13 promoter. Endogenous FOXO3a activation results in marked upregulation of Mmp13 expression which is capable of promoting extracellular matrix degradation and apoptotic cell death.
Von Willebrand factor is normally synthesized in the endoplasmic reticulum of endothelial cells lining blood vessels (and also in megakaryocytes), and it is then packaged into multimers (many strands of vWF connected by disulfide bonds) by the Golgi and stored in Weibel-Palade bodies as a helical spiral of multiple multimers. When vWF is secreted by endothelial cells, the multimers are cleaved by the enzyme ADAMTS13 and vWF circulates in the plasma in a coiled and inactive form. When there is damage to a blood vessel (due to trauma or other factors) collagen under the blood vessel lining is exposed. When vWF comes into contact with exposed collagen it uncoils and binds to the collagen. Circulating platelets bind to vWF using their GpIb-alpha surface protein which binds to a specific area on the uncoiled vWF strand (The A1 domain binding site). Upon binding, the platelets become activated and irregularly shaped which attracts more platelets to the area of vascular damage to form a platelet plug in the blood vessel wall and stop the bleeding. In VWD, vWF is either deficient (type 1 disease), dysfunctional (type 2 disease), or is completely absent (the severe type 3 disease) leading to dysfunction in the above mechanism to stop bleeding. Circulating vWF also binds to coagulation factor VIII preventing it from being degraded. Factor VIII is involved in the coagulation cascade to also prevent excessive bleeding. Von Willebrand factor is mainly active in conditions of high blood flow and shear stress.
Natural iron (26Fe) consists of four stable isotopes: 5.85% 54Fe, 91.75% 56Fe, 2.12% 57Fe and 0.28% 58Fe. There are 28 known radioisotopes and 8 nuclear isomers, the most stable of which are 60Fe (half-life 2.62 million years) and 55Fe (half-life 2.7562 years). Much of the past work on measuring the isotopic composition of iron has centered on determining 60Fe variations due to processes accompanying nucleosynthesis (e.g., meteorite studies) and ore formation. In the last decade however, advances in mass spectrometry technology have allowed the detection and quantification of minute, naturally occurring variations in the ratios of the stable isotopes of iron. Much of this work has been driven by the Earth and planetary science communities, though applications to biological and industrial systems are beginning to emerge.
Sources: en.wikipedia.org
=== Sources === Grant, Michael (1993). The History of Rome. Faber and Faber. ISBN 0-571-11461-X. Lane Fox, Robin (2005). The Classical World. Penguin Books. ISBN 0-14-102141-1. Matyszak, Philip (2004). The Enemies of Rome. New York: Thames and Hudson. ISBN 0-500-25124-X. Musti, Domenico (1990). "La spinta verso il Sud: espansione romana e rapporti "internazionali"". Storia di Roma. Vol. I. Turin: Einaudi. ISBN 978-88-06-11741-2.
Liraglutide, sold under the brand name Victoza among others, is an anti-diabetic medication used to treat type 2 diabetes, and chronic obesity. It is a second-line therapy for diabetes following first-line therapy with metformin. Its effects on long-term health outcomes like heart disease and life expectancy are unclear. It is given by injection under the skin. Liraglutide is a glucagon-like peptide-1 receptor agonist (GLP-1 receptor agonist) also known as incretin mimetics. It works by increasing insulin release from the pancreas and decreases excessive glucagon release. Common side effects include low blood sugar, nausea, dizziness, abdominal pain, and pain at the site of injection. Gastrointestinal side-effects tend to be strongest at the beginning of treatment period and subside over time. Other serious side effects may include angioedema, pancreatitis, gallbladder disease, and kidney problems. Use in pregnancy and breastfeeding is of unclear safety. Liraglutide was approved for medical use in the European Union in 2009, and in the United States in 2010. It is available as a generic medication. In 2023, it was the 209th most commonly prescribed medication in the United States, with more than 2 million prescriptions.
=== Halides === Erbium(III) fluoride is a pinkish powder that can be produced by reacting erbium(III) nitrate and ammonium fluoride. It can be used to make infrared light-transmitting materials and up-converting luminescent materials, and is an intermediate in the production of erbium metal prior to its reduction with calcium. Erbium(III) chloride is a violet compounds that can be formed by first heating erbium(III) oxide and ammonium chloride to produce the ammonium salt of the pentachloride ((NH4)2ErCl5) then heating it in a vacuum at 350-400 °C. It forms crystals of the aluminium chloride type, with monoclinic crystals and the point group C2/m. Erbium(III) chloride hexahydrate also forms monoclinic crystals with the point group of P2/n (P2/c) - C42h. In this compound, erbium is octa-coordinated to form [Er(H2O)6Cl2]+ ions with the isolated Cl− completing the structure. Erbium(III) bromide is a violet solid. It is used, like other metal bromide compounds, in water treatment, chemical analysis and for certain crystal growth applications. Erbium(III) iodide is a slightly pink compound that is insoluble in water. It can be prepared by directly reacting erbium with iodine.
Prakash and Kamal Hinduja, as well as their son Ajay and his wife Namrata, who are members of Britain's richest family, are convicted and sent to prison for exploiting staff brought from India to work in their Geneva villa. 22 June Thousands of people join the "Restore Nature Now" march through central London to Parliament Square, demanding action on the UK's declining wildlife. The UK Health Security Agency (UKHSA) and Met Office issue a yellow heat health alert for most of England, to come into force from the morning of Monday 24 June and remain in place until the afternoon of Thursday 27 June. Following criticism from other party leaders over his comments about Putin, Nigel Farage pens an op-ed in The Telegraph in which he says he has never been an "apologist or supporter" of Putin, but that "if you poke the Russian bear with a stick, don't be surprised if he responds". 23 June Flights from Manchester Airport's Terminals 1 and 2 are cancelled following a "major" power cut. 2024 United Kingdom general election date betting controversy: The Sunday Times reports that Nick Mason, the Conservative Party's chief data officer, has become the fourth person to face investigation by the Gambling Commission for betting on the date of the election. BBC News reports that the Gambling Commission's investigation involves more people than those already named. 24 June Princess Anne is taken to hospital with a head injury thought to have been caused by a horse. The UK records its hottest temperature of 2024 so far, with 28.3 °C recorded at Wisley in Surrey.
Sources: en.wikipedia.org
The names are often used interchangeably in casual writing, but they are not strictly identical. Modified GRF(1-29) refers to the unconjugated analogue carrying only the four substitutions. The version sold as CJC-1295 with DAC includes the albumin binding linker and clears much more slowly.
DAC stands for drug affinity complex, a term describing the maleimidopropionic acid linker. This group forms a covalent bond with the cysteine residue on serum albumin after administration. The resulting adduct is what extends the circulating half life from minutes to days.
No. It is entirely synthetic and does not correspond to any known endogenous peptide. The design starts from human growth hormone releasing hormone and introduces deliberate substitutions. Any biological effect comes from mimicking the natural hormone at its receptor.
Mass spectrometry establishes whether the observed molecular weight matches the calculated sequence mass. Chromatographic retention and fragment mapping add further confidence about sequence and composition. A single technique alone is rarely treated as sufficient evidence of identity.