Buying CJC-1295 in the USA: DAC and No-DAC Are Different Products

Two versions of CJC-1295 circulate, and they get run together constantly. What separates them is one chemical addition, but that addition reshapes the pharmacokinetic profile enough that the two belong in the laboratory as distinct research materials.

The sequence underneath both forms

Each form is constructed on a modified fragment of growth hormone-releasing hormone, namely GHRH(1-29), which is the shortest fragment still carrying full receptor activity. GRF(1-29) is the opening 29 residues of the 44-residue native hormone. Native GHRH(1-29) disappears quickly, with dipeptidyl peptidase-4 cutting between residues 2 and 3, so CJC-1295 carries four amino acid substitutions that block that cleavage and close off other degradation routes.

Each substitution answers a different loss pathway

• D-Ala at position 2 — position 2’s native alanine is the dipeptidyl peptidase-4 cleavage site, and switching to the D-enantiomer strips away the recognition geometry the enzyme requires. Most of the resistance to rapid degradation comes from this one change.
• Gln at position 8 — substituted for an asparagine, which eliminates an asparagine-glycine style deamidation liability at that site.
• Ala at position 15 — substituted for a glycine, changing local flexibility.
• Leu at position 27 — substituted for a methionine, which takes the sequence’s only oxidation-capable residue out. It is the reason the no-DAC form never shows the “mass 16 above target” oxidation impurity that a methionine-containing sequence would.

Taken together these are four distinct answers to four distinct ways a peptide gets lost. The general pattern is covered in our note on what sets a peptide’s half-life.

DAC is a handle, not a pharmacophore

DAC abbreviates Drug Affinity Complex, which in practice is a maleimidoproprionic acid group hung off the C-terminus. Its role has nothing to do with the receptor. It supplies a reactive handle that forms a covalent bond with a free cysteine thiol on circulating serum albumin, after which the peptide travels bound to a large, long-lived protein instead of circulating on its own. Albumin’s circulating half-life runs to several days, and the peptide inherits that timescale rather than clearing at its own rate.

Strip the DAC away and the modified GHRH fragment keeps every substitution that resists enzymatic degradation but has no albumin anchor, which leaves exposure comparatively brief. That is the form the literature and supplier catalogs sometimes list as modified GRF(1-29).

So persistence is the axis on which the two differ, not target. Both engage the GHRH receptor; the modification governs how long the molecule stays available. That is precisely what makes them separate research tools rather than two doses of one tool. A fixed-incubation assay will read them differently, and any comparison that leaves the incubation unstated is not comparing like with like. See Ki, IC50 and EC50.

Numbers that separate them

Mass is the fastest discriminator, and these are the figures to hunt for on a certificate:

• Without DAC (listed also as Mod GRF 1-29): C152H252N44O42, roughly 3,367.9 g/mol, CAS 863288-34-0, sequence [D-Ala2, Gln8, Ala15, Leu27]-GRF(1-29) amide.
• With DAC: C165H269N47O46, roughly 3,647.2 g/mol, CAS 446262-90-4.

About 280 Da stands between them, a wide and unambiguous gap for any mass spectrometer, which is why the observed mass on a certificate is the one check worth leaning on. Two vials both reading “CJC-1295” can hold molecules 280 Da apart, and no quantity of purity reporting will reveal which is which when the mass goes unreported.

Why the confusion persists

Three causes, and recognizing them is most of the defense. The name CJC-1295 gets applied to both forms in the literature and in the market, frequently without qualification. The no-DAC form also answers to Mod GRF (1-29), a synonym that is regularly mistaken for a separate compound. And 280 Da spread across a molecule near 3,400 Da comes to under 10 percent, which nothing but a mass measurement is going to catch.

Which yields a simple working rule: treat the name as inadequate and read the mass. A certificate offering a purity percentage with no observed mass has not established which molecule the vial holds. Listings that drop “DAC” or “no DAC” are ambiguous by construction, so confirm which form a certificate of analysis covers before building an experiment around it.

What the reactive handle means at the bench

Being reactive by design, the maleimide group brings practical consequences the no-DAC form is free of:

• It can react with nucleophiles other than albumin, whether in a buffer or in a stopper, making this the more condition-sensitive of the two forms.
• Maleimide hydrolysis produces a species that has lost function while staying at nearly the same mass, which is a difficult impurity to detect.
• The added group is hydrophobic, so reverse-phase retention moves appreciably. One form’s chromatogram is not a reference for the other’s.

See where peptide impurities come from and how HPLC and mass spectrometry verify purity.

Pulsatile versus sustained receptor occupancy

GHRH receptor signaling is pulsatile in vivo. An agonist with brief exposure and one with extended exposure therefore interrogate different questions: the first approximates a pulse, the second holds the receptor occupied. Work comparing pulsatile against continuous GHRH-receptor stimulation is not interchangeable, and a design written around one form does not carry over to the other.

Published pharmacology for CJC-1295, and for albumin-binding peptide conjugates more generally, is indexed at PubMed, with the wider albumin-conjugation approach covered by this search.

Paired with a secretagogue

A common design places CJC-1295 alongside a growth hormone secretagogue-receptor agonist such as ipamorelin. That arrangement is a two-receptor experiment, not a more forceful single-receptor one: GHRH analogs work at the GHRH receptor while secretagogues work at GHSR-1a, and the two receptors couple by different routes. That separation is the stated rationale for examining them within one model. See GHRH analogs versus growth hormone secretagogues and Ipamorelin and GHSR-1a selectivity.

We stock the no-DAC form and a CJC-1295 and ipamorelin blend, together with other growth hormone pathway peptides. Where the two arrive pre-combined, the per-component mass is what makes the vial interpretable — see what cost per milligram hides.

ExoLabz supplies compounds for laboratory research use only. Nothing on this page is medical advice or a suggestion of human or veterinary use. Third-party reports we have obtained are published on our certificates of analysis page.