This is a working overview of Mod GRF(1-29), written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-04-03 and is reviewed periodically as new material appears.
Enzymatic protection is a separate mechanism from plasma protein binding. The four substitutions in the backbone reduce recognition by dipeptidyl peptidase IV, which normally cleaves the natural hormone within minutes. Without the reactive group, this resistance still yields only a short window of activity, generally reported in the range of tens of minutes. With it, reported half-lives in early human work extended to several days. The size of that gap is the main practical distinction between the two materials.
Both forms act at the pituitary receptor for growth hormone-releasing hormone and increase growth hormone output, which in turn raises insulin-like growth factor 1. A long-acting analog produces sustained rather than pulsatile stimulation, and the physiological consequences of that pattern are not fully settled. Published human data on the extended form remain limited, and much of what circulates in discussion traces to early company reports rather than independent replication. How sustained exposure affects normal feedback remains an open question.
CJC-1295 is a synthetic peptide designed to mimic growth hormone-releasing hormone (GHRH), the endogenous signal that prompts the pituitary gland to release growth hormone. The compound is a modified fragment of the natural hormone, spanning the first twenty-nine amino acids of GHRH with several substitutions that slow enzymatic breakdown. Two variants circulate in research settings: one carrying a drug affinity complex (DAC) and one without it. The DAC-free form is frequently labelled Mod GRF(1-29) in catalogs and discussion forums.
The peptide binds GHRH receptors on somatotroph cells within the anterior pituitary, triggering a signalling cascade that increases growth hormone secretion. Its improved resistance to dipeptidyl peptidase IV degradation distinguishes it from the parent hormone. In the DAC-bearing version, a maleimide group reacts with a cysteine residue on serum albumin, forming a covalent bond that keeps the peptide in circulation far longer. That albumin attachment is the central design feature separating the two research variants.
| Property | Value | Notes |
|---|---|---|
| Duration with linker | Several days | Reported in early human work |
| Duration without linker | Tens of minutes | Short plasma residence |
| Albumin attachment site | Cysteine-34 | Covalent maleimide reaction |
| Primary receptor | Pituitary GHRH receptor | Stimulates growth hormone release |
| Downstream marker | Insulin-like growth factor 1 | Indirect measure of activity |
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.
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.
Reconstitution is typically performed with sterile water or bacteriostatic water, added slowly against the vial wall. The resulting solution should be clear and colorless; cloudiness or visible particles suggest a problem with the material or the diluent. Once in solution, the peptide is less stable than the dry powder. Refrigerated storage at two to eight degrees Celsius is common for short-term holding, while freezing aliquots is described for longer periods.
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.
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 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.
=== Pain === Paracetamol is used for the relief of mild to moderate pain such as in headaches, muscle aches, minor arthritis pain, and toothaches, as well as pain caused by cold, flu, sprains, and dysmenorrhea. It is recommended, in particular, for acute mild to moderate pain; evidence for its treatment of chronic pain is insufficient.
=== β-hairpin motif === A very simple structural motif involving β-strands is the β-hairpin, in which two antiparallel strands are linked by a short loop of two to five residues, of which one is frequently a glycine or a proline, both of which can assume the dihedral-angle conformations required for a tight turn or a β-bulge loop. Individual strands can also be linked in more elaborate ways with longer loops that may contain α-helices.
1911 – Marie Sklodowska-Curie – discovery of radium & polonium 1935 – Irène Joliot-Curie – artificial radioactivity 1964 – Dorothy Crowfoot Hodgkin – protein crystallography 2009 – Ada E. Yonath – structure & function of the ribosome 2018 – Frances Arnold – directed evolution to engineer enzymes 2020 – Emmanuelle Charpentier and Jennifer Doudna – for CRISPR gene editing 2022 - Carolyn R. Bertozzi - for bioorthogonal chemistry Eight women have won the Nobel Prize in Chemistry (listed above), awarded annually since 1901 by the Royal Swedish Academy of Sciences. Marie Curie was the first woman to receive the prize in 1911, which was her second Nobel Prize (she also won the prize in physics in 1903, along with Pierre Curie and Henri Becquerel – making her the only woman to be award two Nobel prizes). Her prize in chemistry was for her "discovery of the elements radium and polonium, by the isolation of radium and the study of the nature and compounds of this remarkable element." Irene Joliot-Curie, Marie's daughter, became the second woman to be awarded this prize in 1935 for her discovery of artificial radioactivity. Dorothy Hodgkin won the prize in 1964 for the development of protein crystallography. Among her significant discoveries are the structures of penicillin and vitamin B12. Forty five years later, Ada Yonath shared the prize with Venkatraman Ramakrishnan and Thomas A. Steitz for the study of the structure and function of the ribosome.
Sources: en.wikipedia.org
Homoserine dehydrogenase catalyzes the reaction of aspartate-semialdehyde (ASA) to homoserine. The overall reaction reduces the C4 carboxylic acid functional group of ASA to a primary alcohol and oxidizes the C1 aldehyde to a carboxylic acid. Residues Glu 208 and Lys 117 are thought to be involved in the active catalytic site of the enzyme. Asp 214 and Lys 223 have been shown to be important for hydride transfer in the catalyzed reaction. Once the C4 carboxylic acid is reduced to an aldehyde and the C1 aldehyde is oxidized to a carboxylic acid, experiments suggest that Asp 219, Glu 208 and a water molecule bind ASA in the active site while Lys 223 donates a proton to the aspartate-semialdehyde C4 oxygen. Homoserine dehydrogenase has an NAD(P)H cofactor, which then donates a hydrogen to the same carbon, effectively reducing the aldehyde to an alcohol. (Refer to figures 1 and 2). However, the precise mechanism of complete homoserine dehydrogenase catalysis remains unknown. The homoserine dehydrogenase-catalyzed reaction has been postulated to proceed through a bi-bi kinetic mechanism, where the NAD(P)H cofactor binds the enzyme first and is the last to dissociate from the enzyme once the reaction is complete. Additionally, while both NADH and NADPH are adequate cofactors for the reaction, NADH is preferred. The Km of the reaction is four-times smaller with NADH and the Kcat/Km is three-times greater, indicating a more efficient reaction. Homoserine dehydrogenase also exhibits multi-order kinetics at subsaturating levels of substrate.
=== Vinylic selenides === Vinylic selenides are organoselenium compounds that play a role in organic synthesis, especially in the development of convenient stereoselective routes to functionalized alkenes. Although various methods are mentioned for the preparation of vinylic selenides, a more useful procedure has centered on the nucleophilic or electrophilic organoselenium addition to terminal or internal alkynes. For example, the nucleophilic addition of selenophenol to alkynes affords, preferentially, the Z-vinylic selenides after longer reaction times at room temperature. The reaction is faster at a high temperature; however, the mixture of Z- and E-vinylic selenides was obtained in an almost 1:1 ratio. On the other hand, the adducts depend on the nature of the substituents at the triple bond. Conversely, vinylic selenides can be prepared by palladium-catalyzed hydroselenation of alkynes to afford the Markovnikov adduct in good yields. There are some limitations associated with the methodologies to prepare vinylic selenides illustrated above; the procedures described employ diorganoyl diselenides or selenophenol as starting materials, which are volatile and unstable and have an unpleasant odor. Also, the preparation of these compounds is complex.
A branded version called Cortrosyn, which was created and developed by Organon and was approved by the FDA in 1970, and as of January 2017 was under the control of Amphastar Pharmaceuticals, and there were three generic versions under ANDAs, one for Mylan approved in 2009, one for Sandoz/Novartis, approved in 2012, and another for Amphastar under ANDA 016750. This version is a powder that is reconstituted before use. A version of cosyntropin in solution (as opposed to powder) was developed by Sandoz/Novartis and was approved under the 505b(2) pathway in 2008; as of January 2017 it had been discontinued. In the UK, available forms of tetracosactide/cosyntropin, the synthetic form of corticotrophin, have been approved for both therapeutic and diagnostic uses, and have included:
Sources: en.wikipedia.org
A maleimide moiety reacts with the thiol of cysteine-34, forming a covalent bond. The reaction occurs in circulation without enzymatic catalysis.
The group is intended to alter distribution and persistence, not receptor engagement. The peptide portion still binds the pituitary receptor, so the primary difference is duration rather than potency.
Not firmly. Early reports describe several days for the extended form, but independent confirmations are sparse, and values vary with assay method and study design.
The synthetic peptide keeps the receptor-binding region of GHRH but carries substitutions that resist enzymatic cleavage. In the DAC version, an added group also anchors the molecule to albumin, extending its presence in the bloodstream.