Compound reference
CJC-1295 with DAC vs without DAC: what the DAC changes
Published 2026-10-31 · updated 2026-10-31 · vendor-authored explanatory note
Short answer
Both materials start from the same idea: a modified version of the first 29 amino acids of growth hormone-releasing hormone, GHRH(1-29), with four substitutions that make it more resistant to enzymatic breakdown. The version without DAC stops there and is often called modified GRF(1-29). The version with DAC adds a lysine at the C-terminus carrying a maleimidopropionyl group that reacts with albumin, which is what extends its time in circulation in published studies. Because they are different molecules with different masses, a mass-spec identity result is the simplest way to tell them apart.
Catalog materials discussed on this page
| Without DAC (mod GRF 1-29) | With DAC | |
|---|---|---|
| Core sequence | Substituted GHRH(1-29) | Substituted GHRH(1-29) |
| C-terminal addition | None | Lysine with 3-maleimidopropionamide group |
| Albumin binding | No reactive group for albumin | Maleimide reacts with albumin Cys34 |
| Plasma persistence in published studies | Short | Detected beyond 72 h in rats; half-life 5.8 to 8.1 days estimated in a clinical study |
| How to confirm identity | Mass spec matches the no-DAC mass | Mass spec matches the DAC mass |
Shared backbone
GHRH(1-29) is the shortest fragment of the natural hormone that keeps its activity at the GHRH receptor in laboratory models. Native GHRH(1-29) is broken down quickly, largely by the enzyme dipeptidyl peptidase-IV, which cuts after the second residue.
The four substitutions in CJC-1295 are designed to slow that breakdown. Both the DAC and no-DAC materials share this substituted 29-residue sequence.
What the DAC adds
DAC stands for Drug Affinity Complex. In CJC-1295 with DAC, an extra lysine is added at the C-terminus and its side chain carries a 3-maleimidopropionamide group. A maleimide reacts with free thiol groups, and serum albumin has one at cysteine 34.
In a 2005 rat study, the authors bioconjugated maleimido derivatives of GHRH(1-29) to human serum albumin, picked the best one (CJC-1295), and found it still present in plasma beyond 72 hours, with an immunoreactive band at the albumin position on a Western blot. A later clinical pharmacology study estimated its plasma half-life at 5.8 to 8.1 days. Unmodified GHRH(1-29), by comparison, is generally described as lasting only minutes in circulation.
Telling them apart on a COA
The two materials have different molecular weights, because the DAC version carries the extra lysine and maleimide linker. The product pages list the molecular weight for each. An LC-MS or MALDI identity result should match the material you ordered; a mass that matches the other form means the vial is mislabeled.
Names in the market are messy. You will see CJC-1295 no DAC, CJC-1295 without DAC, Mod GRF 1-29, and modified GRF(1-29) used for the no-DAC material. Read the reported mass, not just the name. HPLC purity will not tell you which form you have, since both can be equally pure.
- Compound name exactly as ordered (with DAC or without DAC)
- Observed mass from LC-MS or MALDI compared with the expected mass for that form
- HPLC purity with method
- Lot number that matches the vial
Blends
Some catalogs pair CJC-1295 without DAC with ipamorelin in one vial. A COA for a blend should identify both components by mass and report purity for each, or state clearly how the blend was tested. A single purity number for a two-peptide vial is hard to interpret.
Related on Vitality Chems
- Verify a lot — enter the lot number on your vial to open its report.
- CJC-1295 with DAC — lot records and COA status.
- CJC-1295 no DAC — lot records and COA status.
- CJC-1295 w/o DAC + Ipamorelin — lot records and COA status.
- Sermorelin — lot records and COA status.
- Tesamorelin — lot records and COA status.
- GHRH analogs vs ghrelin-receptor agonists — where CJC-1295 sits among related compounds.
- HPLC vs LC-MS — why mass spec tells the two forms apart.
- Peptide COA checklist — ten checks for any certificate of analysis.
Frequently asked
Is mod GRF 1-29 the same as CJC-1295 without DAC?
In most catalogs, yes. Both names refer to the tetrasubstituted GHRH(1-29) without the C-terminal DAC lysine. Confirm with the reported mass.
Can HPLC purity tell me which form I have?
No. Purity says how clean the sample is, not which molecule it is. Use the mass-spec identity result.
Why does the DAC version persist longer?
Its maleimide group reacts with albumin, a long-lived plasma protein, so the peptide is carried along with it in published animal and clinical pharmacokinetic studies.
References
- Jetté L et al. Human growth hormone-releasing factor (hGRF)1-29-albumin bioconjugates activate the GRF receptor on the anterior pituitary in rats. Endocrinology. 2005;146(7):3052-3058.Design of maleimido GRF(1-29) derivatives and albumin binding of CJC-1295 in rats.
- Teichman SL et al. Prolonged stimulation of growth hormone (GH) and insulin-like growth factor I secretion by CJC-1295, a long-acting analog of GH-releasing hormone. J Clin Endocrinol Metab. 2006;91(3):799-805.Pharmacokinetic half-life estimate for CJC-1295.
