This is a working overview of DAC linker, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2025-11-06. Anything still debated is marked as such rather than presented as settled.
Two principal forms appear in the literature and in research supply. One carries a drug affinity complex, a maleimide-based group that forms a covalent bond with circulating albumin. This linkage slows clearance and produces a long-lasting elevation of peptide levels. The other form lacks that group and is often labeled MOD GRF(1-29). It has a much shorter circulation time. Both variants retain the same core receptor-binding sequence. Reported half-lives differ substantially between the two.
At the pituitary, the peptide binds the growth hormone-releasing hormone receptor on somatotroph cells. Receptor activation raises intracellular cyclic AMP and triggers release of stored growth hormone. Somatostatin and other hypothalamic signals modulate this response. Negative feedback from insulin-like growth factor 1 also influences output. The same regulatory architecture operates with the native hormone. Whether the synthetic analog alters feedback dynamics over repeated exposure remains an open question. Most published receptor work uses cell models rather than intact human systems.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular weight, DAC form | About 3647 Da | Varies with salt form |
| Molecular weight, non-DAC form | About 3358 Da | MOD GRF(1-29) |
| Solubility class | Water soluble | Also dissolves in polar solvents |
| Reported half-life, DAC form | About five to eight days | Values from human studies |
| Common synonyms | CJC-1295; MOD GRF(1-29) | Name depends on variant |
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.
The second form adds a maleimide-bearing linker to the lysine at the carboxyl end. This group reacts with cysteine-34 on circulating serum albumin, forming a covalent bond that keeps the peptide in the bloodstream for far longer. ConjuChem developed the molecule as a way to extend the action of a peptide without frequent administration. The albumin attachment is the defining structural feature of the drug affinity complex version. Whether continuous exposure produces effects distinct from shorter pulses remains an unresolved research question.
CJC-1295 is a synthetic analogue of growth hormone-releasing hormone, built on the 29-amino-acid GHRH(1-29) fragment. Four substitutions distinguish it from the natural sequence: D-alanine at position 2, glutamine at position 8, alanine at position 15, and leucine at position 27. These changes reduce enzymatic cleavage and extend the peptide's persistence in circulation. The compound is discussed in two forms, one carrying a drug affinity complex and one without it.
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.
Oral treatment: (brand names Daktarin in UK, Fungimin Oral Gel in Bangladesh): In 2010, the US Food and Drug Administration approved Oravig (miconazole) buccal tablets for the local treatment of oropharyngeal candidiasis, more commonly known as thrush, in adults and children age 16 and older. External skin treatment (brand names Desenex and Zeasorb in US and Canada; Micatin, Monistat-Derm, Daktarin in India, UK, Australia, Belgium and the Philippines; Kalpanax in Indonesia; Daktar in Norway; Fungidal in Bangladesh; Decocort in Malaysia) (Note that Desenex originally contained not miconazole, but rather the fungistatic agents, undecylenic acid and zinc undecylenate, which were in the foot powder developed by the US government for troops during WWII.) Vaginal treatment (brand names Miconazex, Monistat, Femizol or Gyno-Daktarin in UK):
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== Development == In early embryogenesis, the esophagus develops from the endodermal primitive gut tube. The ventral part of the embryo abuts the yolk sac. It is very small in the beginning, but it lengthens due to descent of lungs and heart. During the second week of embryological development, as the embryo grows, it begins to surround parts of the sac. The enveloped portions form the basis for the adult gastrointestinal tract. The sac is surrounded by a network of vitelline arteries. Over time, these arteries consolidate into the three main arteries that supply the developing gastrointestinal tract: the celiac artery, superior mesenteric artery, and inferior mesenteric artery. The areas supplied by these arteries are used to define the midgut, hindgut and foregut. The surrounded sac becomes the primitive gut. Sections of this gut begin to differentiate into the organs of the gastrointestinal tract, such as the esophagus, stomach, and intestines. The esophagus develops as part of the foregut tube. The esophagus develops as a tube, lined with smooth muscle but continues development craniocaudally into different proportions of striated muscle. Both types of muscle have been demonstrated to be of different precursor cells. The innervation of the esophagus develops from the pharyngeal arches.
Sources: en.wikipedia.org
== Structure and reactivity == Atractyloside is a hydrophilic glycoside. A modified glucose is linked to the hydrophobic diterpene atractyligenin by a β1-glycosidic bond. A carboxyl group is positioned at the C4 position in the axial position. The glucose part is esterified with isovaleric acid on the C2' atom, and sulfuric acid on the C3' and C4' atoms. By hydrolysis a molecule of D-(+)-glucose, isovaleric acid, atractyligenin, and two molecules of sulfuric acid could be obtained. The two sulfate groups and the carboxyl group in ATR are in a deprotonated form under physiological conditions. Thus, ATR is triple negatively charged.
== Participants == The negotiations involved senior political, diplomatic, and security officials from both countries. The United States delegation of nearly 300 members was led by Vice President JD Vance and included senior officials such as special envoy Steve Witkoff and presidential adviser Jared Kushner. According to a senior official cited by BBC News, the broader delegation also included National Security Adviser Andrew Baker and Asian affairs adviser Michael Vance. Additional subject-matter experts were present in Islamabad, with further support teams based in Washington, D.C. The Iranian delegation consisted of around 70 members, led by parliamentary speaker Mohammad Bagher Ghalibaf and Foreign Minister Abbas Araghchi, along with additional political, security, and economic officials. The reported members included:
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Sources: en.wikipedia.org
It is a synthetic peptide modeled on growth hormone-releasing hormone. The molecule is used in research on pituitary growth hormone secretion. It differs from the natural hormone through several stabilizing substitutions.
The DAC form carries a maleimide group that binds albumin and extends circulation time. The non-DAC form lacks this group and clears much faster. Both share the same receptor-binding core.
It targets the growth hormone-releasing hormone receptor on pituitary somatotroph cells. Activation raises cyclic AMP and promotes growth hormone release. Normal feedback pathways remain part of the response.
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.