Is CJC-1295 29 or 30 residues?

29. GRF(1-29) means residues 1 to 29, ending in a C-terminal amide rather than a thirtieth residue.

How does the DAC linker attach to albumin?

Maleimide reacts with albumin's Cys34, the only free cysteine in the protein, forming a stable covalent thioether bond.

Why is there no sulfur in the formula?

The substitutions replace the methionine present in native GRF(1-29).

CJC-1295 Molecular Structure

The short answer

CJC-1295 is a 29-residue peptide with a C-terminal amide, based on GRF(1-29) with substitutions at positions 2, 8, 15 and 27. The DAC form adds a maleimidopropionic acid linker that couples covalently to cysteine-34 of serum albumin.

Key facts

Length: 29 residues, C-terminal amide
Substitutions: D-Ala2, Gln8, Ala15, Leu27
DAC linker: Maleimidopropionic acid
Albumin target: Cysteine-34
With DAC: 3647.2 Da, C165H269N47O46
Without DAC: 3367.9 Da, C152H252N44O42
Sulfur: None (methionine substituted out)

The 29-residue count

GRF(1-29) means residues 1 through 29 of GHRH, and PubChem's systematic name for the peptide enumerates exactly 29, terminating in L-argininamide. Descriptions of CJC-1295 as a 30-residue peptide, including in an earlier version of this article, mistake the C-terminal amide for an additional residue.

Why the C-terminal amide matters

Native GHRH is amidated at its C-terminus, and the modification is not cosmetic: it removes a negative charge and blocks carboxypeptidase attack. Reproducing it in an analogue preserves both the native electrostatics and that protection.

Research material referenced

CJC-1295 + Ipamorelin 5+5mg, third-party HPLC tested

Buy CJC-1295 + Ipamorelin · £36.99

Each substitution in turn

D-Ala2 defeats DPP-4, which cleaves GHRH after position 2. Gln8 replaces an asparagine prone to deamidation. Ala15 and Leu27 address further degradation-prone points. Collectively they also remove the methionine that native GRF(1-29) carries, which is why the formula contains no sulfur where sermorelin's does.

The maleimide chemistry

Maleimide reacts selectively with free thiols under mild conditions, forming a stable thioether. Serum albumin carries exactly one free cysteine, Cys34, making it an unusually clean target for this chemistry. The reaction happens in circulation after administration rather than during manufacture, so the peptide is supplied unconjugated and finds its carrier in vivo.

What the structure does not include

No cysteine in the peptide itself, so no disulfide chemistry and no competing thiol for the maleimide. No methionine after the substitutions. That combination makes the DAC chemistry specific: the only free thiol available is albumin's.

Frequently asked questions

Is CJC-1295 29 or 30 residues?: 29. GRF(1-29) means residues 1 to 29, ending in a C-terminal amide rather than a thirtieth residue.
How does the DAC linker attach to albumin?: Maleimide reacts with albumin's Cys34, the only free cysteine in the protein, forming a stable covalent thioether bond.
Why is there no sulfur in the formula?: The substitutions replace the methionine present in native GRF(1-29).

Extended research context

The CJC-1295 & Ipamorelin deep dive

Deep dive: why CJC-1295 and Ipamorelin are studied together

CJC-1295 is a modified GHRH (growth-hormone-releasing hormone) analogue; Ipamorelin is a selective growth-hormone secretagogue that binds the ghrelin receptor (GHS-R1a). In pituitary-cell research models the two act on independent pathways whose downstream effect converges on GH release. CJC-1295 amplifies the endogenous GHRH signal while Ipamorelin adds a separate ghrelin-pathway stimulus. That's why supplier catalogues frequently package them together as a research reference blend.

DAC vs no-DAC: which CJC-1295 is which

'CJC-1295 with DAC' contains a Drug Affinity Complex (a Lys-maleimide moiety) that binds serum albumin and extends half-life to several days. 'CJC-1295 no-DAC' (also called Modified GRF 1-29) lacks the linker and clears in minutes. These are pharmacologically different peptides. A CoA must specify which form is in the vial; mass differs (~3,367 Da with DAC vs ~3,367 minus linker for no-DAC).

Ipamorelin's selectivity profile

Unlike earlier GHS-R agonists (e.g. GHRP-6), Ipamorelin was engineered for minimal cross-activity at cortisol- and prolactin-releasing pathways in research models. That receptor selectivity is why it is the reference secretagogue for controlled pituitary-cell studies.

Research applications

▸Pituitary-cell GH-release assays (comparator vs GHRH and hexarelin)
▸Half-life comparison studies: DAC vs no-DAC CJC-1295 forms
▸Ghrelin-receptor binding assays for Ipamorelin analogue development
▸Analytical HPLC method development for lipidated GHRH analogues
▸Stability testing under refrigerated storage

Handling checklist

✓Store lyophilised at −20 °C long-term
✓Reconstitute in bacteriostatic water; both peptides dissolve readily
✓Aliquot immediately, refrigerate at 2–8 °C, use within 28 days
✓Confirm salt form and DAC/no-DAC status on CoA before starting a study
✓Do not use for human administration (research reference only)

Common research-handling mistakes

Learnt from thousands of researcher orders across our UK labs.

✗ Confusing DAC and no-DAC CJC-1295

Fix: Check the CoA. The two have very different pharmacokinetics.

✗ Assuming Ipamorelin acts on GHRH receptors

Fix: It binds the ghrelin receptor (GHS-R1a), a separate pathway from CJC-1295.

✗ Storing reconstituted solution at room temperature

Fix: Refrigerate 2–8 °C after reconstitution.

Continue researching

Peer-reviewed guides, comparators and matched reference materials.

Primary sources & clinical trials

Peer-reviewed research and registered trials from PubMed, ClinicalTrials.gov, PubChem, FDA and NIH. All links open in a new tab and point to the primary source, so every claim can be verified at origin.

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Written and reviewed by

The UK Peptides Editorial Team · Research library, UK Peptides

The editorial team is responsible for supplier selection, batch release decisions and the content published in this research library. Every article here is sourced to primary literature and every product page to a signed third-party certificate. Corrections are made in place and the review date updated.

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