Alpha-helical peptide ribbon with four highlighted residue positions, representing the substitutions in Modified GRF(1-29)

CJC-1295 Explained: Modified GRF(1-29) and the DAC Modification

Key takeaways

CJC1295 is a 29-residue GHRH(1-29) analog with four substitutions: D-Ala2, Gln8, Ala15, Leu27, plus a C-terminal amide.
Each substitution removes a degradation route: DPP-IV cleavage, deamidation, helix instability, methionine oxidation.
No-DAC form (Modified GRF(1-29)): CAS 863288-34-0, C152H252N44O42, 3367.95 g/mol. DAC form adds a maleimidopropionyl-lysine (about 3647 g/mol).
The catalog carries the no-DAC peptide alone (5 mg) and in the ipamorelin blend; neither contains a maleimide.
For in vitro research use only.

CJC1295 is the name given to a synthetic 29-residue analog of growth-hormone-releasing hormone, GHRH(1-29), carrying four amino-acid substitutions (D-Ala2, Gln8, Ala15, Leu27) and a C-terminal amide; the un-derivatized peptide is called Modified GRF(1-29) or CJC-1295 no DAC (CAS 863288-34-0, C₁₅₂H₂₅₂N₄₄O₄₂, 3367.95 g/mol), while the name CJC-1295 alone usually means the same sequence with an extra lysine carrying a maleimidopropionyl Drug Affinity Complex. This guide explains where the sequence comes from, what each substitution does, how the two forms differ, and which one the catalog carries.

Where does the CJC-1295 sequence come from?

Native human GHRH is a 44-residue peptide. Its amino-terminal 29 residues, GHRH(1-29), carry essentially all of the receptor-binding activity, and this fragment (as sermorelin) has long been the reference GHRH-receptor agonist in vitro. CJC1295 peptide keeps the GHRH(1-29) backbone and changes four positions to remove the chemical weak points of the native sequence. A related, differently modified GHRH analog, tesamorelin, is profiled in Tesamorelin: GHRH-analog structure, and the parent fragment in sermorelin as a GHRH-analog reference compound.

What do the four substitutions do?

Position	Native GHRH(1-29)	Modified GRF(1-29)	Chemical reason
2	L-Ala	D-Ala	Blocks dipeptidyl-peptidase-IV cleavage between residues 2 and 3
8	Asn	Gln	Removes the asparagine most prone to deamidation at Asn8-Ser9
15	Gly	Ala	Stabilizes the amphipathic alpha-helix that the receptor recognizes
27	Met	Leu	Removes the methionine sulfur that oxidizes in solution

Full sequence of the no-DAC form: Tyr-D-Ala-Asp-Ala-Ile-Phe-Thr-Gln-Ser-Tyr-Arg-Lys-Val-Leu-Ala-Gln-Leu-Ser-Ala-Arg-Lys-Leu-Leu-Gln-Asp-Ile-Leu-Ser-Arg-NH₂. Each change targets a specific degradation route (enzymatic cleavage, deamidation, oxidation) or a conformational weakness, so the analog survives longer in assay buffer and gives more reproducible receptor-binding data than the native fragment. Note that a few catalogs copy the native Asn8 and Met27 into their listed sequence; the PubChem record for CJC1295 Without DAC (CID 91976842) and the molecular formula C₁₅₂H₂₅₂N₄₄O₄₂ correspond to Gln8 and Leu27.

What is the DAC modification?

DAC stands for Drug Affinity Complex. In the DAC form a thirtieth residue, lysine, is added at the C-terminus and its side-chain amine is acylated with 3-maleimidopropionic acid. The maleimide ring is a thiol-reactive group: in a protein-containing medium it forms a covalent thioether with a free cysteine, notably Cys34 of serum albumin. PubChem lists this conjugate as CJC 1295 (CID 91971820, C₁₆₅H₂₆₉N₄₇O₄₆, about 3647 g/mol). The structural and handling differences between the two forms are compared in CJC-1295 with DAC vs no DAC.

Which form does the catalog carry?

CJC-1295 no DAC is the un-derivatized Modified GRF(1-29), supplied as a 5 mg lyophilized powder. The same peptide is one half of the Ipamorelin/CJC-1295 (no DAC) blend, which is profiled in the CJC-1295 + ipamorelin blend profile. Neither product contains a maleimide group, so neither reacts with albumin in serum-containing culture medium.

Naming variants and misspellings

The compound appears as CJC-1295, CJC1295, CJC 1295, Mod GRF(1-29), Modified GRF 1-29, and in misspelled forms such as cj1295 or cjc1259. They all refer to the same 29-residue sequence; the only distinction that matters chemically is whether the DAC lysine is present. On a Certificate of Analysis, identity rests on the mass spectrum, not the name: the no-DAC peptide gives a multiply charged envelope with [M+4H]⁴⁺ at about 843.0 and [M+3H]³⁺ at about 1123.6, as explained in mass spectrometry for peptide identity confirmation.

How is CJC-1295 no DAC studied in vitro?

As a GHRH-receptor agonist, in cAMP-accumulation and CRE-reporter assays in GHRH-R-expressing cells, with sermorelin or GHRH(1-44) as the reference agonist. The assay design is the same as for other GHRH analogs; see GHRH-receptor binding and cAMP assay design.

Related research guides

Research-use note

All materials discussed are supplied for in vitro laboratory research use only, and are not for human or animal use.

Frequently asked questions

What is CJC1295?

A synthetic 29-residue analog of GHRH(1-29) with four substitutions (D-Ala2, Gln8, Ala15, Leu27) and a C-terminal amide; the un-derivatized peptide is Modified GRF(1-29) or CJC-1295 no DAC, 3367.95 g/mol, and the name CJC-1295 alone usually denotes the same sequence with a maleimidopropionyl Drug Affinity Complex on an added lysine. View CJC-1295 no DAC

What does DAC mean in CJC-1295?

Drug Affinity Complex: a 3-maleimidopropionyl group on a C-terminal lysine whose maleimide reacts covalently with a free thiol such as albumin Cys34.

Is Modified GRF(1-29) the same as CJC-1295 no DAC?

Yes. Both names refer to the 29-residue substituted GHRH analog without the DAC lysine.

How do I confirm the identity of CJC-1295 no DAC?

By the mass spectrum on the COA: a multiply charged envelope with [M+4H]4+ near 843.0 and [M+3H]3+ near 1123.6, consistent with C152H252N44O42. MS identity guide

Is CJC-1295 for human or animal use?

No. It is supplied for in vitro laboratory research use only.