A practical reference on DAC group: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2026-06-15 and is reviewed periodically as new material appears.
Two related peptides circulate under the CJC-1295 label, and they differ mainly in how long they persist in circulation. The version carrying a drug affinity complex includes a maleimidopropionic acid linker that forms a covalent bond with serum albumin. The other version, usually written as modified GRF(1-29) or tetrasubstituted GRF(1-29), lacks that linker and is cleared quickly. Mixing the two produces inconsistent readings of published half-life values, because the linker rather than the receptor-facing sequence drives most of the difference.
The core sequence keeps the receptor-binding region of GHRH while replacing four positions that are vulnerable to dipeptidyl peptidase-4 and other proteases. Substitutions at positions 2, 8, 15, and 27 raise metabolic stability relative to the natural hormone. The N-terminal residues remain essential for activity, so changes there generally lower potency. Molecular weight sits near 3368 daltons for the tetrasubstituted analog without the linker, while the albumin-binding form is heavier because of the added maleimide group.
CJC-1295 is a synthetic peptide modeled on growth hormone-releasing hormone, the hypothalamic signal that prompts the pituitary to release growth hormone. Its sequence corresponds to the first twenty-nine residues of human GHRH, with four substitutions that slow enzymatic breakdown. Early descriptions placed the compound in research on growth hormone deficiency and related conditions, and later literature groups it with the long-acting GHRH analogs. The name appears in both laboratory and popular fitness writing, where it sometimes labels chemically different peptides.
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.
Four amino acid substitutions separate the modified backbone from the parent GRF(1-29) sequence. These changes reduce recognition by dipeptidyl peptidase IV and related proteases, extending the interval before degradation. Development work in this area sought longer-acting GHRH analogs for endocrine investigation. Published descriptions treat the substitution set as a defining property of the core sequence, while the albumin-binding linker is described separately as an optional addition to that same backbone.
| Property | Value | Notes |
|---|---|---|
| Class | Synthetic peptide | GHRH receptor agonist |
| Sequence length | 29 amino acids | Derived from human GHRH |
| Molecular weight | About 3368 Da without linker | Albumin-binding form is heavier |
| Appearance | White to off-white lyophilized powder | Common form for research reference material |
| Typical storage | -20 °C or below, desiccated | Protect powder from light and moisture |
Lyophilized peptide powder is comparatively stable when kept dry, cold, and protected from light. Once dissolved, the molecule is vulnerable to deamidation, oxidation, and aggregation, with the rate depending on pH, buffer composition, and temperature. Alkaline conditions and repeated freeze-thaw cycles accelerate loss of the intact peptide. The methionine present in the native sequence is a known oxidation site, which is one reason it was replaced in the modified fragment. Suppliers typically recommend cold storage of solutions and use within a short window.
Analytical confirmation usually relies on reversed-phase high-performance liquid chromatography for purity and on liquid chromatography coupled to mass spectrometry for identity. Mass data reveal the expected molecular mass and can flag truncated or oxidized species. Amino acid analysis and peptide mapping provide sequence-level verification. Immunoassays are used in some biological matrices, but antibodies raised against one releasing-hormone analog may cross-react with another. Reported purity figures depend heavily on the method used, so comparisons between suppliers require matching the analytical approach.
The two variants differ dramatically in how long they persist in circulation. The form lacking the albumin-binding group has a plasma half-life measured in tens of minutes, comparable to the natural hormone fragment. The version carrying the drug affinity complex binds albumin and shows a half-life of roughly six to eight days in human studies. That figure comes from small trials that tracked hormone levels over extended periods. The physiological consequences of sustained versus pulsatile stimulation are still debated and the literature does not settle the point.
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.
Naming in this area is inconsistent, and readers should treat product labels with care. In much of the literature and in vendor catalogs, the unqualified term refers to the albumin-binding version, while the version lacking the DAC group appears as modified GRF(1-29), mod GRF(1-29), or the same name with a without-DAC qualifier. Because one abbreviation has been applied to both materials, the only reliable way to identify a sample is to check the stated sequence and the presence of the linker.
The compound emerged from work at a Canadian biotechnology firm in the early 2000s. Early human studies examined its effect on growth hormone and insulin-like growth factor 1 in healthy volunteers and in people with HIV-associated fat redistribution. Reports described sustained increases in both markers after a single injection. Development did not advance to regulatory approval, and the clinical programme was later discontinued. The molecule is now encountered mainly as a research chemical rather than a marketed medicine.
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.
== Advantages == APPI is most used for LC/MS although it has recently found widespread use in ambient applications such as detection of explosives and narcotics compounds for security applications using ion mobility spectrometry. Compared to the more commonly used predecessor ionization sources ESI and APCI, APPI ionizes a broader range of compounds with the benefit increasing toward the non-polar end of the scale. It also has relatively low susceptibility to ion suppression and matrix effects, which makes APPI very effective in detecting compounds quantitatively in complex matrices. APPI has other advantages including a broader linear range and dynamic range than ESI as seen by the example in the left figure. It is also generally more selective than APCI with reduced background ion signals as shown in the right figure. This latter example also highlights the benefit of APPI vs. ESI in that the HPLC conditions were for non-polar normal-phase in this case using n-hexane solvent. ESI requires polar solvents and further hexane could pose an ignition hazard for ESI and APCI that use high voltages. APPI works well under normal-phase conditions since many of the solvents are photoionizable and serve as dopant ions, which allows specialized applications such as separation of enantiomers (right figure).
Half-Life 2 is a 2004 first-person shooter (FPS) game developed and published by Valve Corporation. It was published for Windows on Valve's digital distribution service, Steam. Like the original Half-Life (1998), Half-Life 2 combines combat, puzzles and storytelling, and adds features such as vehicles and physics-based gameplay. The player controls Gordon Freeman, who joins a resistance effort to liberate Earth from the alien Combine empire. Half-Life 2 was created using Valve's Source game engine, which was developed simultaneously. Development lasted five years and cost US $40 million. Valve's president, Gabe Newell, set his team the goal of redefining the FPS genre. They integrated the Havok physics engine, which simulates real-world physics, to reinforce the sense of presence and create new gameplay. They also developed the characterization, with more detailed character models and animations. Valve announced Half-Life 2 at E3 2003 with a release date of September of that year. They failed to meet the release date, leading to fan backlash. In October, the unfinished source code was published online, leading to more backlash and damage to the team's morale. Half-Life 2 was released on Steam on November 16, 2004. It won 39 Game of the Year awards and, like its predecessor, has been cited as one of the most influential FPS games and among the greatest games ever made. It was ported to the Xbox, the Xbox 360, the PlayStation 3, macOS, and Linux. By 2011, it had sold 12 million copies.
=== Overview of European experience in nuclear partitioning === A lot of research funded by the European Commission is being devoted to hydrometallurgical processes for the partitioning and transmutation of trivalent actinides (An). These research programs have first led to multicycle processes, secondly to the development of simplified and innovative processes. The hydrometallurgical partitioning consists of two relevant steps: extraction and stripping. In the first step the organic phase, containing the extracting ligand dissolved in a suitable solvent, is contacted with the aqueous phase coming from the dissolution of the irradiated fuel. The solutes present in the aqueous phase are extracted by a complexation reaction with the extracting agent and transferred into the organic phase in which the formed complexes are soluble. The second step, known as stripping, is obtained by reversing the complexation reaction, where the solutes are back-extracted into another aqueous solution usually different in acidity compared to the previous one. The main goal is to develop reliable and affordable industrial separation processes by lipophilic and hydrophilic ligands to selectively extract minor actinides from the (3–4) M acidic target waste downstream of the PUREX process, but with the more challenging goal to minimize the amount of solid secondary waste.
Sources: en.wikipedia.org
== External links == Media related to Scutellaria at Wikimedia Commons Data related to Scutellaria at Wikispecies "Scutellaria L. (skullcap)". The PLANTS Database. United States Department of Agriculture. Scutellaria images. MorphBank.
==== Multifunctional alginate scaffolds ==== Multifunctional alginate scaffolds for T cell engineering and release (MASTER) is a technique for in situ engineering, replication and release of genetically engineered T cells. It is an evolution of CAR T cell therapy. T cells are extracted from the patient and mixed with a genetically engineered virus that contains a cancer-targeting gene (as with CAR T). The mixture is then added to a MASTER (scaffold), which absorbs them. The MASTER contains antibodies that activate the T cells and interleukins that trigger cell proliferation. The MASTER is then implanted into the patient. The activated T cells interact with the viruses to become CAR T cells. The interleukins stimulate these CAR T cells to proliferate, and the CAR T cells exit the MASTER to attack the cancer. The technique takes hours instead of weeks. And because the cells are younger, they last longer in the body, show stronger potency against cancer, and display fewer markers of exhaustion. These features were demonstrated in mouse models. The treatment was more effective and longer-lasting against lymphoma.
An increasingly popular trend is to freeze-dry the animal. For all intents and purposes, a freeze-dried mount is a mummified animal. The internal organs are removed during preparation; however, all other tissue remains in the body. (The skeleton and all accompanying musculature is still beneath the surface of the skin) The animal is positioned into the desired pose, then placed into the chamber of a special freeze-drying machine designed specifically for this application. The machine freezes the animal and also creates a vacuum in the chamber. Pressure in the chamber helps vaporize moisture in the animal's body, allowing it to dry out. The rate of drying depends on vapor pressure. (The higher the pressure, the faster the specimen dries.) Vapor pressure is determined by the temperature of the chamber; the higher the temperature, the higher the vapor pressure is at a given vacuum. The length of the dry-time is important because rapid freezing creates less tissue distortion (i.e.; shrinkage, warping, and wrinkling) The process can be done with reptiles, birds, and small mammals such as cats, rodents, and some dogs. Large specimens may require up to six months in the freeze dryer before they are completely dry. Freeze-drying is the most popular type of pet preservation. This is because it is the least invasive in terms of what is done to the animal's body after death, which is a concern of owners (Most owners do not opt for a traditional skin mount).
== Biological function == In 1962, J.C. Watkins reported synthesizing NMDA, an isomer of the previously known N-Methyl-DL-aspartic-acid. NMDA is a water-soluble D-alpha-amino acid — an aspartic acid derivative with an N-methyl substituent and D-configuration — found across Chordates from lancelets to mammals. At homeostatic levels NMDA plays an essential role as a neurotransmitter and neuroendocrine regulator. At increased but sub–toxic levels NMDA becomes neuroprotective. In excessive amounts NMDA is an excitotoxin. Behavioral neuroscience research utilizes NMDA excitotoxicity to induce lesions in specific regions of an animal subject's brain or spinal cord to study behavioral changes. The mechanism of action for the NMDA receptor is a specific agonist binding to its NR2 subunits, and then a non-specific cation channel is opened, which can allow the passage of Ca2+ and Na+ into the cell and K+ out of the cell. Therefore, NMDA receptors will only open if glutamate is in the synapse and concurrently the postsynaptic membrane is already depolarized - acting as coincidence detectors at the neuronal level. The excitatory postsynaptic potential (EPSP) produced by activation of an NMDA receptor also increases the concentration of Ca2+ in the cell. The Ca2+ can in turn function as a second messenger in various signaling pathways. This process is modulated by a number of endogenous and exogenous compounds and plays a key role in a wide range of physiological (such as memory) and pathological processes (such as excitotoxicity).
Sources: en.wikipedia.org
Natural GHRH is degraded quickly by dipeptidyl peptidase-4 and related enzymes, giving it a half-life measured in minutes. CJC-1295 carries substitutions that slow that breakdown, so it stays intact longer. Both act at the same pituitary receptor and produce the same class of signal.
The label was first attached to the albumin-binding form during early development work. A shorter analog without the linker later became known by the same name in informal use. Published papers normally state which version was studied, so the methods section resolves the ambiguity.
It is a synthetic peptide rather than a steroid, and it does not occur naturally in the body. Its sequence is derived from a hypothalamic hormone called growth hormone-releasing hormone. It works as a receptor agonist rather than as a replacement for that hormone.
No. It is a laboratory-synthesized analog built on a fragment of the natural hormone. The natural peptide is shorter-lived and lacks the stabilizing substitutions found in the synthetic version.