CJC-1295 with and without DAC — two different molecules
The DAC and no-DAC forms of CJC-1295 are distinct compounds with different masses and different CAS numbers. How to tell which one a COA describes.
CJC-1295 is sold in two forms that are chemically distinct, not two grades of one product. The no-DAC form is Mod GRF (1-29), CAS 863288-34-0, molecular weight 3367.89 g/mol. The DAC form carries an added drug affinity complex group, which raises its mass. The molecular weight on a COA is what identifies which is in the vial.
By the Bench Grade Research Team ·
What DAC actually refers to
DAC stands for drug affinity complex — a maleimidoproprionic acid group attached to the peptide. It is a covalent modification, not an additive or a formulation choice, and a peptide carrying it is a different molecule with a different formula, different mass and its own CAS number.
The no-DAC form is more precisely called Mod GRF (1-29): the first 29 residues of growth hormone releasing factor, with four amino acid substitutions that resist enzymatic breakdown. Suppliers use CJC-1295 no DAC and Mod GRF (1-29) interchangeably, and in this case the two names genuinely do describe the same compound.
Identity at a glance — the no-DAC form
| Property | Value |
|---|---|
| CAS Registry Number | 863288-34-0 |
| Molecular formula | C152H252N44O42 |
| Molecular weight | 3367.89 g/mol |
| Also known as | Mod GRF (1-29) |
| Basis | GRF (1-29) with four substitutions |
| Common vial sizes | 5 mg, 10 mg |
Why the four substitutions exist
Native GRF (1-29) is cleaved rapidly by dipeptidyl peptidase. The four substitutions in the modified sequence sit at positions that resist that cleavage, which is why the modified peptide is the form used in laboratory work rather than the native sequence.
This is worth knowing when reading a COA because the sequence line should show the substituted residues, including a D-alanine at position two. A sequence matching native GRF (1-29) exactly is not the compound most protocols were written against.
How the DAC modification actually extends half-life
The maleimidoproprionic acid group is not a slow-release coating. Maleimide chemistry reacts with thiol groups, and serum albumin carries an accessible free cysteine — so the modified peptide forms a covalent bond with a circulating protein that is itself cleared slowly.
The peptide's half-life becomes tied to albumin's rather than to its own susceptibility to enzymatic breakdown. That is a different strategy from the amino acid substitutions in the no-DAC form, which resist cleavage by changing the substrate rather than by attaching it to something long-lived.
Two solutions to the same problem, and why both persist
| Mod GRF substitutions (no DAC) | Drug affinity complex (DAC) | |
|---|---|---|
| Strategy | Resist enzymatic cleavage | Bind to a slowly cleared carrier protein |
| What is modified | Four amino acid positions | A group appended to the peptide |
| Mass effect | About +10 Da over sermorelin | About +279 Da over Mod GRF |
| Result described | Cleavage-resistant peptide | Peptide tethered to albumin |
Neither strategy supersedes the other, which is why both forms remain in the research market. A study measuring a short pulse of receptor activity and a study measuring sustained exposure are different experiments, and the appropriate molecule differs between them. A supplier presenting one form as an upgrade on the other has described a preference rather than a fact.
What both forms act on
Both are analogs of growth hormone releasing factor and are described in the literature as acting at the GHRH receptor. The modifications change how long the molecule survives to do that, not what it does — which is why the substitutions and the DAC group sit away from the region that engages the receptor.
Handling
- At 3368 g/mol this is a mid-sized peptide, and the usual handling applies — reconstitute at room temperature, direct solvent at the glass wall, and do not shake.
- The sequence includes tyrosine, so detection at 280 nm is available as a secondary check alongside peptide-bond absorbance at 214 nm.
- A 5 mg vial in 2 mL gives 2.5 mg/mL nominal, about 0.74 mM at this molecular weight.
What the CJC-1295 literature examined
The published work indexed in the research library concerns growth hormone secretion measured in animal and clinical research settings, including studies of pulsatile secretion. Those are the primary sources and they describe research findings rather than approved applications.
References
Primary literature for the compounds discussed above. Links open the record on PubMed.
- Pulsatile secretion of growth hormone (GH) persists during continuous stimulation by CJC-1295, a long-acting GH-releasing hormone analog Ionescu M, et al. J Clin Endocrinol Metab. 2006. PMID 17018654 → · summary
- Prolonged stimulation of growth hormone (GH) and insulin-like growth factor I secretion by CJC-1295, a long-acting analog of GH-releasing hormone, in healthy adults Teichman SL, et al. J Clin Endocrinol Metab. 2006. PMID 16352683 → · summary
Primary sources
- Pulsatile secretion of growth hormone (GH) persists during continuous stimulation by CJC-1295, a long-acting GH-releasing hormone analogJ Clin Endocrinol Metab · 2006
- Prolonged stimulation of growth hormone (GH) and insulin-like growth factor I secretion by CJC-1295, a long-acting analog of GH-releasing hormone, in healthy adultsJ Clin Endocrinol Metab · 2006
Frequently asked questions
- What is the difference between CJC-1295 with and without DAC?
- They are chemically distinct molecules. The DAC form carries an added maleimidoproprionic acid group — the drug affinity complex — which changes the formula, the mass and the CAS number. The no-DAC form is Mod GRF (1-29) at 3367.89 g/mol.
- Is CJC-1295 no DAC the same as Mod GRF (1-29)?
- Yes. Unlike most interchangeable peptide names, these two genuinely describe the same compound: GRF (1-29) with four amino acid substitutions that resist enzymatic cleavage, CAS 863288-34-0.
- How can I tell which form of CJC-1295 a COA describes?
- By the molecular weight. A figure near 3368 g/mol is the no-DAC form. A materially higher mass indicates the DAC-modified molecule. If the COA reports no mass, it cannot distinguish them and neither can the vial label.
Compounds discussed in this guide
More on identification
- CJC-1295 with DAC — the other molecule, and how to tell them apartThe DAC form is 279 daltons heavier than the no-DAC form and has its own CAS. One number on the COA separates them.
- Sermorelin — GHRH (1-29) and the peptide family built on itSermorelin is the unmodified first 29 residues of growth hormone releasing hormone. Every GHRH analog in this market is a modification of it.
- Semax — an ACTH fragment with a Pro-Gly-Pro tailSemax is ACTH (4-7) with a proline-glycine-proline tail attached. That tail is a design decision shared with Selank, and it explains both compounds.
All products discussed in this guide are supplied by Bench Grade Peptides for laboratory research use only. Not for human or veterinary use.