CJC-1295 is a synthetic analogue of growth hormone releasing hormone built on the GRF(1-29) fragment with four residue substitutions. It is supplied in two forms that share the same receptor pharmacology and differ only in whether a thirtieth residue carries an albumin-binding linker. NuVion supplies the 29-residue form, CJC-1295 No DAC, as a laboratory chemical for in vitro research use only. Supplier catalogues frequently mix the two forms up, so the distinction is set out below with the numbers for each.
Key facts
| Type | Synthetic GHRH analogue, supplied in two forms |
| Amino acid count | 29 (No DAC) or 30 (with DAC) |
| Substitutions | D-Ala2, Gln8, Ala15, Leu27 on GRF(1-29) |
| Molecular formula | C152H252N44O42 (No DAC); C165H269N47O46 (with DAC) |
| Molecular weight | 3367.9 g/mol (No DAC); 3647.2 g/mol (with DAC) |
| CAS number | 446262-90-4 (No DAC form) |
| Synonyms | Modified GRF 1-29, Mod GRF (1-29), CJC-1295 DAC, DAC:GRF |
| Supplied form | Lyophilised powder in a sealed vial |
Structure and chemistry
The starting point is GRF(1-29), the first twenty-nine residues of human growth hormone releasing hormone, which is the shortest fragment that retains full activity at the receptor. Four positions are substituted to slow enzymatic breakdown and to remove sites of chemical instability: D-alanine at position 2 blocks cleavage by dipeptidyl peptidase 4, glutamine at position 8 removes an asparagine prone to deamidation, alanine at position 15 sits in place of a glycine, and leucine at position 27 replaces a methionine that would otherwise oxidise. That substituted 29-residue peptide is CJC-1295 No DAC, also written modified GRF 1-29, with a molecular weight near 3368 g/mol.
The DAC form adds a thirtieth residue, a lysine whose side chain carries 3-maleimidopropionic acid. The maleimide group reacts selectively with free thiols, and in serum the accessible cysteine 34 of albumin is the dominant partner, producing a covalent peptide to protein conjugate that circulates with albumin instead of being cleared as a free peptide. That linker is the drug affinity complex the DAC abbreviation refers to, and it is the only structural difference between the two. It adds roughly 279 mass units, giving the higher figure near 3647 g/mol.
Those two numbers are the reliable way to tell the forms apart, because the naming is not consistent across suppliers. A listing that pairs the No DAC name with a molecular weight near 3647, or the with-DAC name with a weight near 3368, has combined data from the two molecules. Both forms are characterised the same way, by RP-HPLC for purity and mass spectrometry for identity, although the DAC peptide must be analysed before exposure to serum: once conjugated, the species detected is albumin plus the peptide at roughly 70 kDa, outside the working range of a standard peptide method.
Mechanism of action
Both forms bind the growth hormone releasing hormone receptor, a class B1 G protein-coupled receptor expressed on pituitary somatotrophs, and couple through Gs to adenylate cyclase. Cyclic AMP rises, protein kinase A is activated, and the transcription factor Pit-1 together with CREB phosphorylation drives transcription at the growth hormone gene. In cultured somatotrophs the measurable readouts are cAMP accumulation, CREB phosphorylation by western blot, and growth hormone in the medium by ELISA. Potency at the receptor is comparable between the two forms.
The difference sits in exposure time and not in receptor behaviour. Free GRF(1-29) is cleared from serum within minutes, both by dipeptidyl peptidase 4 acting on the N-terminal dipeptide and by renal filtration of a small peptide. The four substitutions blunt the first route, which is what the No DAC form provides, and albumin conjugation removes the second by raising the hydrodynamic size well above the glomerular cut-off. In serum-stability work the conjugate persists on a scale of days where the unconjugated peptide persists on a scale of hours. Because albumin conjugation is the mechanism for the DAC form, the concentration of free thiol in the experimental medium sets how much of it converts, which makes serum-free and serum-containing conditions behave differently.
Research applications
- Pituitary somatotroph culture: cAMP accumulation and growth hormone secretion measured against unmodified GRF(1-29) as the short-acting comparator.
- Serum stability studies comparing the substituted 29-residue peptide with the DAC conjugate by LC-MS over hours to days.
- Dipeptidyl peptidase 4 resistance assays, following the N-terminal dipeptide and the effect of the D-Ala2 substitution.
- GHRH receptor binding and selectivity panels against related class B1 receptors including those for secretin, VIP and glucagon.
- Structure-activity comparisons across GHRH analogues including sermorelin, tesamorelin and the unmodified GRF(1-29) fragment.
- Receptor cross-talk experiments pairing a GHRH receptor agonist with a ghrelin receptor agonist on the same preparation.
CJC-1295 sits in NuVion’s Growth Hormones category alongside the other compounds acting on this axis.
Handling in the laboratory
CJC-1295 No DAC is supplied lyophilised and is reconstituted with bacteriostatic water added slowly down the wall of the vial and swirled, not shaken, because agitation at an air interface promotes aggregation in longer peptides. The reconstitution calculator converts vial content and diluent volume into a stock concentration. The peptide is basic enough to dissolve readily in water; where a stock is prepared for cell work it is diluted into buffered medium and a vehicle control accounts for the benzyl alcohol carried over from the diluent.
Unopened vials are kept sealed, dry, away from light and refrigerated as stated on the product documentation. Reconstituted solution is refrigerated and used within the period given on that documentation, or aliquoted and frozen so that repeated freeze-thaw cycles are avoided. Material of the DAC form has an extra constraint: the maleimide hydrolyses to an unreactive maleamic acid as pH rises, so it is held at mildly acidic pH and used promptly where the linker is to stay reactive.
Testing and supply from NuVion
NuVion’s CJC-1295 No DAC is manufactured at a GMP-audited facility and independently tested by Janoshik Analytical, with purity determined by RP-HPLC and identity confirmed by mass spectrometry. Most batches are tested, and the Certificate of Analysis for a tested batch is published on the product page and in the COA library. The peptide is supplied lyophilised in sealed vials and dispatched from within Australia. The DAC conjugate is not part of the current range.
Related compounds
Other compounds acting at or below the same receptor include sermorelin, the unmodified GRF(1-29) amide, and tesamorelin, a full-length GHRH(1-44) analogue with an N-terminal acyl group. The ghrelin receptor agonists ipamorelin, GHRP-2 and GHRP-6 act through a separate receptor on the same cell type and are often run alongside it.
Frequently asked questions
What is the difference between CJC-1295 and CJC-1295 No DAC?
The No DAC form is the 29-residue substituted GRF(1-29) peptide on its own, near 3368 g/mol. The DAC form adds a thirtieth lysine carrying a maleimidopropionyl group that bonds covalently to albumin, near 3647 g/mol. Receptor pharmacology is the same; the conjugate persists in serum far longer. The residue count and molecular weight are the reliable way to tell them apart, since the names are used inconsistently.
Is CJC-1295 No DAC the same as modified GRF 1-29?
Yes. Modified GRF 1-29, Mod GRF (1-29) and CJC-1295 No DAC all describe the same molecule: GRF(1-29) with the D-Ala2, Gln8, Ala15 and Leu27 substitutions and no albumin linker. It carries CAS number 446262-90-4.
What does DAC stand for?
Drug affinity complex. It describes the maleimide linker chemistry that forms a covalent bond with a free thiol on circulating albumin, so the peptide travels as part of a protein conjugate instead of being filtered out as a small peptide.
Is CJC-1295 a therapeutic good in Australia?
No. NuVion’s CJC-1295 No DAC is a laboratory chemical for in vitro research. It is not included in the Australian Register of Therapeutic Goods, has not been assessed by the Therapeutic Goods Administration, and is not for human or veterinary use.
Research use only. This product is a laboratory chemical supplied for in vitro research. It is not included in the Australian Register of Therapeutic Goods and has not been assessed by the Therapeutic Goods Administration for quality, safety or efficacy. It is not for human or veterinary use, and nothing on this page is a representation about therapeutic use.
