HPLC · CoA
CJC-1295 DAC vs No DAC: What Is the Difference?
Comparison · 7 min read · Updated 30 September 2026
The difference in CJC-1295 DAC vs no DAC is one chemical group at the C-terminus of an otherwise identical peptide. Both vials contain modified GRF 1-29, a 29 residue GHRH analogue with four protective substitutions. In the DAC form, an extra lysine bearing a maleimide linker bonds covalently to serum albumin, so the analogue circulates with that protein and remains measurable for days rather than minutes. The added group raises the mass from about 3,368 to about 3,647 daltons.
We stock both forms, and confusing one with the other is the error we correct most frequently in this category. Naming history accounts for most of it.
Why Do Two Peptides Share the Name CJC-1295?
Two peptides share the name because suppliers extended the original CJC-1295 code, which belonged to the albumin-binding molecule, to the plain modified chain. The albumin-binding compound was reported in Endocrinology in 2005. The plain 29 residue chain already existed as modified GRF 1-29, sometimes written tetrasubstituted GRF 1-29, and was later listed as CJC-1295 without DAC. A protocol that names only CJC-1295 is therefore ambiguous. Every label we print states with DAC or no DAC, and a laboratory notebook should record the same distinction.
Which Substitutions Do Both Forms Carry?
Both forms carry the same four substitutions, which correct the weak points of native GHRH 1-29. The native fragment, supplied as sermorelin, degrades quickly in plasma.
- D-alanine replaces alanine at position 2, blocking dipeptidyl peptidase-4 from trimming the first two residues
- Glutamine replaces asparagine at position 8, a residue prone to deamidation
- Alanine replaces glycine at position 15, which stabilises the helix and receptor contact
- Leucine replaces methionine at position 27, removing an oxidation-prone side chain
CJC-1295 no DAC in 2mg, 5mg and 10mg fills is that chain with a C-terminal amide, mass near 3,368 daltons. At the somatotroph it engages the GHRH receptor and raises cyclic AMP as the natural hormone does, but it persists long enough to produce a clean, measurable pulse in a sample.
What Is the Drug Affinity Complex Made Of?
The drug affinity complex is a lysine added at position 30 whose side chain carries maleimidopropionic acid, a group that reacts selectively with free thiols. CJC-1295 with DAC uses that chemistry against the single free thiol serum albumin offers, at cysteine 34. The reaction forms a stable thioether, tethering the analogue to a 66,000 dalton carrier whose own circulation lasts weeks. Persistence follows the carrier, not the peptide.
Three papers frame the compound. The 2005 Endocrinology study screened albumin bioconjugates of GRF 1-29 in rats and selected this one. Two 2006 papers in JCEM followed it into early clinical pharmacology, one describing its pharmacokinetics and pharmacodynamics and one examining whether pulsatile growth hormone secretion continued under steady stimulation. No regulator has registered it as a medicine.
CJC-1295 DAC vs No DAC Feature by Feature
| Feature | No DAC (Mod GRF 1-29) | With DAC |
|---|---|---|
| Core chain | GRF 1-29, D-Ala2, Gln8, Ala15, Leu27 | Identical |
| Added group | None | Lys30 with maleimidopropionic acid |
| Approximate mass | 3,368 Da | 3,647 Da |
| Albumin attachment | None | Covalent, at albumin Cys34 |
| Time in circulation | Minutes to tens of minutes | Days |
| Receptor stimulation pattern | Brief pulse | Sustained |
| Fills we hold | 2mg, 5mg, 10mg | 2mg, 5mg, 10mg |
| Suits studies of | Pulse timing, pairing with a ghrelin agonist | Long exposure at the GHRH receptor, albumin conjugate chemistry |
How Can the Two Forms Be Told Apart?
The two forms are told apart by mass spectrometry, because a difference of roughly 279 daltons is resolved immediately. Both are white lyophilised cakes, so visual inspection proves nothing. Identity is confirmed by mass spectrometry for every lot we release, alongside HPLC purity of 98% or higher, and the certificate of analysis names the form supplied. A vial labelled with DAC whose reported mass sits near 3,368 contains the plain chain, whatever the packaging states.
Why Does the Ipamorelin Blend Use the No DAC Form?
The no DAC chain is chosen for the ipamorelin blend because both components act briefly, so their signals overlap within one measurable window. Our CJC-1295 and Ipamorelin 10mg blend pairs modified GRF 1-29 at the GHRH receptor with ipamorelin, a five residue agonist at the ghrelin receptor. Synergy between the two receptors can then be read across a narrow interval. Substituting the DAC form changes the design: a brief ghrelin signal is set against releasing hormone activity that never subsides, which suits work on background tone rather than pulse interaction.
Comparing CJC-1295 with DAC against ipamorelin is therefore a comparison of two receptors, not two competing products. One is a long-lived agonist at the releasing hormone receptor, the other a short-lived agonist at the ghrelin receptor, and their targets do not overlap. Single vials of ipamorelin allow a laboratory to assemble either combination and characterise each compound alone first.
Reconstitution Strength by Fill Size
Both forms dissolve readily in preserved diluent. Each cell shows the strength, with the micrograms contained in one U-100 graduation of 0.01 mL in brackets.
| Fill | Plus 1 mL | Plus 2 mL | Plus 3 mL |
|---|---|---|---|
| 2mg | 2 mg per mL (20 mcg) | 1 mg per mL (10 mcg) | 0.67 mg per mL (6.7 mcg) |
| 5mg | 5 mg per mL (50 mcg) | 2.5 mg per mL (25 mcg) | 1.67 mg per mL (16.7 mcg) |
| 10mg | 10 mg per mL (100 mcg) | 5 mg per mL (50 mcg) | 3.33 mg per mL (33.3 mcg) |
How Should the DAC Form Be Handled at the Bench?
The DAC form should be kept away from thiol-containing buffers and prepared close to the time of use, because its maleimide group is reactive. Dithiothreitol, mercaptoethanol and cysteine will consume the linker before albumin can. Hydrolysis of the maleimide ring also competes with the intended reaction if the stock stands in solution for weeks. The plain chain has no such constraint and follows the usual handling for a lyophilised research peptide.
| Form | Sealed powder | In solution |
|---|---|---|
| No DAC | Freezer at -20 °C, dark | Fridge at 2 to 8 °C, weeks under common lab convention |
| With DAC | Freezer at -20 °C, dark | Fridge at 2 to 8 °C, prepare near the time of use, no thiol buffers |
Which Form Suits Which Study Design?
The no DAC form suits studies of defined pulses, and the DAC form suits studies that need receptor stimulation held steady over days.
- Measuring a defined releasing hormone pulse, alone or beside a ghrelin agonist: the plain chain
- Holding receptor stimulation steady across days in a model: the version with the complex
- Studying the maleimide and albumin chemistry itself: the version with the complex
- Setting a control for either: the unmodified sermorelin fragment
Our recommendation for most laboratories entering this area is to begin with the plain chain. It behaves predictably, pairs naturally with a ghrelin agonist, and its short action makes cause and effect easier to attribute in a first experiment. Move to the albumin-binding form only when the question requires sustained exposure. The remaining releasing hormone analogues and secretagogues are grouped in our growth hormone research category.
Questions about CJC-1295 DAC vs no DAC
Sources
- Development of a novel long-acting growth hormone-releasing hormone analog with improved biological activity. Endocrinology. 2005.
- Pharmacokinetics and pharmacodynamics of CJC-1295, a long-acting analog of growth hormone-releasing hormone, in healthy adults. Journal of Clinical Endocrinology and Metabolism. 2006.
Written by the Macropus Peptides technical team for in-vitro laboratory research reference. Not medical advice; products are not for human or veterinary use and are sold to buyers aged 18 and over.