A practical reference on Mod GRF(1-29): what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2025-10-07 and is reviewed periodically as new material appears.
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 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.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C152H252N44O42 | Cited for the form without the drug affinity complex |
| Molecular weight | About 3368 Da | Reported value for modified GRF(1-29) |
| Appearance | White to off-white powder | Lyophilised solid as usually supplied |
| Solubility | Soluble in water and polar solvents | Clarity depends on purity and salt content |
| Typical storage | -20 C or below, dry | Protect from light and repeated warming cycles |
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.
Pharmacokinetic behaviour differs sharply between the two forms. The DAC-bearing peptide shows an extended circulation time measured in days, whereas the version without the complex is cleared within roughly half an hour. This gap shapes how researchers design dosing schedules in animal models. Whether the prolonged presence of the DAC form produces effects meaningfully different from the short-acting variant remains an open question, since comparative human data are scarce.
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 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.
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.
== Career and research == Following his PhD, Scrutton was appointed as Lecturer (1995), then Reader (1997) and Professor (1999) at the University of Leicester before being appointed Professor at the University of Manchester in 2005. He has held successive research fellowships over 29 years from the Royal Commission for the Exhibition of 1851 (1851 Research Fellowship), St John's College, Cambridge, the Royal Society (Royal Society University Research Fellow and Royal Society Wolfson Research Merit Award), the Lister Institute of Preventive Medicine, the Biotechnology and Biological Sciences Research Council (BBSRC) and the Engineering and Physical Sciences Research Council (EPSRC). He has been Visiting Professor at Tsinghua University (Beijing, China) and Cardiff University (UK), and adjunct professor at VISTEC (Thailand) and Beijing University of Chemical Technology (China). He has made major contributions to the study of enzyme catalysis, the mechanisms and structures of enzymes and the photochemistry of photoreceptor proteins. His group has investigated quantum tunnelling and protein dynamics in enzyme H-transfer and conformational ensemble sampling in electron transfer reactions. He has also made contributions to enzyme kinetics, coenzyme chemistry, protein engineering, directed evolution, synthetic biology, biological engineering, biocatalysis and metabolic engineering, including the first rational redesign of the coenzyme specificity of an enzyme, the establishment of automated microorganism bioengineering platforms for the production of chemicals (e.g.
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=== Early career === Early on as an independent investigator, Mrksich developed and executed the concept of dynamic substrates for cell culture. Here, self-assembled monolayers (SAMs) present cell adhesive ligands with perfect control over density and orientation against a non-adhesive, inert background, such as ethylene glycol. These monolayers can be further modified with electroactive groups that selectively release immobilized ligand when stimulated with an electric potential. Several strategies using this approach were studied in the context of cell signaling, migration, and co-culture. Subsequent cell-based work focused on developing methods to pattern cells on the aforementioned SAMs. The work has mostly utilized microcontact printing to confine adherent cells into defined positions, shapes, and sizes. Ultimately, his group's work has revealed examples of how cellular mechanics and cytoskeletal structure influence phenotype. A primary example of this involved investigating how cell shape exerts control over the differentiation of mesenchymal stem cells. Further work utilized these patterned monolayers to investigate the relationship between various cytoskeletal elements and to observe complex phenotypic differences in patient-derived neuroprogenitor cells. Recent work in the group investigating cell patterning has utilized photoactive adhesive peptides, allowing for local, spatiotemporal control of cell adhesion to study gap junction formation.
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The cause of Fukuyama congenital muscular dystrophy is rooted in the FKTN gene, located at human chromosome 9q31, encoding the protein fukutin. Mutations in this gene, and therefore the fukutin protein, are the cause of FCMD. The disease is inherited in an autosomal recessive manner. This means the defective gene responsible for the disorder is located on an autosome (chromosome 9 is an autosome), and two copies of the defective gene (one inherited from each parent) are required in order to be born with the disorder. The parents of an individual with an autosomal recessive disorder both carry one copy of the defective gene but usually do not experience any signs or symptoms of the disorder. Two mutations have been identified. The first and most common is an SVA retrotransposal insertion in the 3'-untranslated region. The second is a deep-intronic point mutation c.647+2084G>T. This second mutation has only been found to date in the presence of the first mutation.
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Sources: en.wikipedia.org
It is a synthetic peptide analogue of growth hormone-releasing hormone. Four substitutions in its sequence make it more resistant to enzymatic degradation than the natural hormone. In the version carrying a drug affinity complex, the peptide binds albumin and remains in circulation for days.
No regulatory agency has approved CJC-1295 for clinical use. Human trials were conducted in the 2000s, but the development programme was discontinued before any marketing application succeeded. Material sold today is offered as a research chemical, and its purity depends on the supplier.
Sermorelin is an unmodified fragment of growth hormone-releasing hormone and is cleared quickly. CJC-1295 contains substitutions that resist breakdown, and the form with a drug affinity complex persists much longer. Both act at the same receptor but differ substantially in duration of action.
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.