CJC-1295 with DAC and without: what the drug affinity complex changes

CJC-1295 is a 30-residue GHRH analogue carrying a maleimide group that bonds to serum albumin. The version sold without DAC is a different, 29-residue molecule. Identity, lineage and 2026 status.

By Touchstone PeptidesSeptember 22, 20266 minute read

CJC-1295 is a synthetic analogue of the first 29 residues of human growth hormone-releasing hormone, with four amino-acid substitutions and a thirtieth residue, a lysine, whose side chain carries a maleimidopropionyl group. That group is the "drug affinity complex" (DAC): a reactive handle that forms a covalent bond with the free thiol on serum albumin. The peptide sold as "CJC-1295 without DAC" or "Mod GRF 1-29" is the same 29-residue substituted chain without the lysine and without the handle, a different molecule with a different mass and CAS number.

Where it comes from: GHRH and GRF(1-29)

Human growth hormone-releasing hormone (GHRH, also GRF, somatoliberin) is a 44-residue amidated peptide cut from a 108-residue precursor (UniProt P01286, residues 32 to 75). Its first 29 residues, as a C-terminal amide, are the peptide known as GRF(1-29)-NH2, which has the INN sermorelin:

YADAIFTNSYRKVLGQLSARKLLQDIMSR-NH2

Its identity block is in the four-molecule comparison, and the catalog lists it as sermorelin. In the literature GHRH and its 1-29 fragment are described as ligands of the GHRH receptor, a G protein-coupled receptor expressed predominantly in the anterior pituitary that was cloned in 1992.

Every CJC molecule starts from this 29-residue chain.

The four substitutions: "modified GRF(1-29)"

Modified GRF(1-29) changes four positions:

Position	Native GRF(1-29)	Modified GRF(1-29) / CJC-1295
2	L-alanine	D-alanine
8	asparagine	glutamine
15	glycine	alanine
27	methionine	leucine

The substituted sequence reads Y-(D-Ala)-DAIFTQSYRKVLAQLSARKLLQDILSR-NH2. PubChem's IUPAC name for CJC-1295 (CID 91971820) confirms each of these positions, including the (2R) configuration at residue 2 that marks the D-alanine.

Two of the four changes replace residues that are chemically fragile in the native chain: asparagine at position 8 (a residue that deamidates in solution) and methionine at position 27 (a residue that oxidizes). The D-alanine at position 2 sits at the site that dipeptidyl peptidase-IV cuts in the native peptide; the ConjuChem paper that introduced CJC-1295 reports that its albumin conjugates showed enhanced in vitro stability against that enzyme. Our storage and stability piece covers why asparagine and methionine matter in any sequence.

The DAC-less peptide is a real, separately registered substance: PubChem CID 56841945, C152H252N44O42, molecular weight 3367.9, CAS 863288-34-0. That is ten daltons heavier than sermorelin (3357.9), the net effect of the four substitutions.

What the DAC is

"Drug affinity complex", DAC, is the name attached to a general strategy: attach a maleimide group to a peptide so that, once in plasma, it reacts with the single free cysteine (Cys34) on serum albumin and rides along on that protein. The 2005 Endocrinology paper that identified CJC-1295 describes the design:

In vivo bioconjugation to the free thiol on Cys34 of serum albumin by a strategically placed reactive group on a bioactive peptide is a useful tool to extend plasma half-life.Jetté L et al., Endocrinology, 2005

In CJC-1295 the reactive group is 3-maleimidopropionic acid, amide-linked to the epsilon-amino group of an added lysine at position 30. The same paper calls the molecule "a tetrasubstituted form of hGRF(1-29) with an added N epsilon-3-maleimidopropionamide derivative of lysine at the C terminus." A maleimide is a five-membered ring with two carbonyls flanking a nitrogen and a reactive double bond; a thiol adds across that double bond to form a stable thioether. Albumin has one such thiol available, so the reaction is selective in plasma.

The arithmetic follows. CJC-1295 is C165H269N47O46, average molecular weight 3647.2 (PubChem CID 91971820), CAS 446262-90-4. Subtract the DAC-less peptide's 3367.9 and the difference, 279.3, is one lysine residue plus one maleimidopropionyl group. The chemistry goal, stated in the sponsor's own publications, was a plasma residence measured in days rather than the short duration of the native hormone; a human pharmacokinetic study published in 2006 reported an estimated half-life on the order of a week.

The catalog's CJC-1295 is listed at molecular weight 3647.2 and CAS 446262-90-4: the DAC form.

Why the naming is a mess

Four names circulate for two molecules:

"CJC-1295" and "CJC-1295 with DAC" both mean the 30-residue maleimide peptide (3647.2).
"CJC-1295 without DAC", "CJC-1295 no DAC" and "Mod GRF 1-29" all mean the 29-residue substituted peptide (3367.9).
PubChem's record for the DAC-less peptide (CID 56841945) lists both "CJC 1295 with DAC" and "CJC-1295-no DAC acetate" as synonyms of the same entry, which is the confusion in miniature.
The related code CJC-1293 appears alongside CJC-1295 on the WADA list; it is a different code and not this molecule.

The only way to know which molecule a vial contains is the certificate's mass-spectrometry identity: an observed mass near 3647 is the DAC form, near 3368 is the DAC-less peptide, near 3358 is plain sermorelin. See reading a chromatogram for how the identity panel is presented.

What it has been studied in

The 2005 paper characterized CJC-1295 in cultured rat anterior pituitary cells and in Sprague-Dawley rats, and reported it present in rat plasma beyond 72 hours and, by Western blot, on the albumin band beyond 24 hours. Early human studies followed, published in 2006 in the Journal of Clinical Endocrinology and Metabolism, and ConjuChem registered a Phase 2 trial (NCT00267527, started December 2005) that ClinicalTrials.gov lists as terminated. No later sponsor has registered a trial. We describe the models, not the findings, because findings in a terminated development program are not a property of a research vial.

Regulatory status as of September 21, 2026

Question	CJC-1295 (with DAC)	Modified GRF(1-29) (without DAC)
FDA-approved product	none	none
Registered trials	one, Phase 2, terminated (ConjuChem)	none found
503A category	outside Category 2 by September 27, 2024; listed as withdrawn on the April 22, 2026 page; in no category, not on the bulks list	never listed under this name
WADA 2026	named in S2.2.4	covered by the same class, "GHRH and its analogues"

CJC-1295 did not leave Category 2 in the April 2026 wave that moved BPC-157 and eleven other peptides. By September 27, 2024 it was already out of Category 2: FDA's page archived that day listed it, with AOD-9604, Selank acetate and thymosin alpha-1, under "Other bulk drug substances that may present significant safety risks", and the April 22, 2026 version of the page lists it as withdrawn. FDA's text for it remains on the page:

FDA has identified serious adverse events associated with CJC-1295 including increased heart rate and systemic vasodilatory reaction.FDA, bulk drug substances page, content current April 22, 2026

WADA's 2026 list, section S2.2.4, names "growth hormone-releasing hormone (GHRH) and its analogues (e.g. CJC-1293, CJC-1295, sermorelin and tesamorelin)", prohibited at all times.

For how CJC-1295 sits next to sermorelin, tesamorelin and ipamorelin, see four molecules, two receptor classes. We also list a catalog blend, CJC-1295 + ipamorelin, whose certificate should identify both peptides separately.

Sources

For laboratory research use only. Not a drug, not a supplement, and nothing here is a claim about what any of this material does in a person or an animal.

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