The short answer
Modified GRF (1-29) is the DAC-free form of CJC-1295: 29 residues at 3367.9 Da, based on the active fragment of human GHRH with four stabilising substitutions. It differs from native GRF(1-29) (sermorelin) by 10.0 Da and by the absence of sulfur in its formula.
Key facts
- Molecular weight
- 3367.9 Da, C152H252N44O42
- PubChem CID
- 56841945
- Length
- 29 residues, C-terminal amide
- Native equivalent
- Sermorelin, 3357.9 Da, C149H246N44O42S
- Substitutions
- D-Ala2, Gln8, Ala15, Leu27
- Half-life
- ~30 minutes
- Sulfur
- None (the substitutions remove the methionine)
Three related compounds
Native GHRH is 44 residues. GRF(1-29) is its active fragment, marketed as sermorelin, at 3357.9 Da with formula C149H246N44O42S. Modified GRF (1-29) is that fragment with four substitutions, at 3367.9 Da and formula C152H252N44O42. CJC-1295 with DAC adds a linker to the modified peptide, reaching 3647.2 Da. Each step is a defined chemical change with a measurable mass consequence.
The detail in the formulae
Sermorelin's formula contains sulfur; Modified GRF's does not. That is because native GRF(1-29) carries a methionine, and the substitution set replaces it. The practical consequence is real: Mod GRF has no methionine to oxidise, so the +16 Da satellite that complicates many peptide spectra should not appear, and its storage requirements differ correspondingly from sermorelin's.
Research material referenced
CJC-1295 + Ipamorelin 5+5mg, third-party HPLC tested
What the substitutions achieve
D-alanine at position 2 blocks DPP-4, which cleaves GHRH after residue 2 and is the principal reason native GHRH has a half-life of minutes. Gln8, Ala15 and Leu27 address further degradation points. Together they extend the peptide's survival substantially without changing its receptor pharmacology. The same design logic as Aib8 in semaglutide, applied to a different hormone.
Why the name is doubly confusing
Modified GRF (1-29) is also called CJC-1295 without DAC, CJC-1295 DAC-free, and simply CJC-1295 by suppliers who do not distinguish. Meanwhile PubChem's record for it carries a 'with DAC' synonym. One compound, at least four names, one of which belongs to a different compound. Mass is the way through.
Why it is the common research pairing
At roughly thirty minutes it is short-acting, which matches ipamorelin's profile. Pairing two short-acting compounds produces a coordinated brief stimulus rather than one sustained and one transient signal. That is the stated rationale for the combination, and it is a design argument rather than a tested result.
Quick reference
| Compound | Formula | MW | CID |
|---|---|---|---|
| Sermorelin, native GRF(1-29) | C149H246N44O42S | 3357.9 | 16132413 |
| Modified GRF (1-29) | C152H252N44O42 | 3367.9 | 56841945 |
| CJC-1295 with DAC | C165H269N47O46 | 3647.2 | 91971820 |
Frequently asked questions
- Is Modified GRF (1-29) the same as CJC-1295?
- It is CJC-1295 without the DAC linker, 3367.9 Da against 3647.2. Suppliers frequently call both simply CJC-1295.
- How does it differ from sermorelin?
- Four substitutions and 10.0 Da. Sermorelin is native GRF(1-29); Mod GRF adds stabilising changes that also remove the methionine.
- Why does the formula have no sulfur?
- The substitution set replaces the methionine that native GRF(1-29) carries, so there is no sulfur-containing residue left.
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.
Related questions researchers ask
- Is CJC-1295 the same as Modified GRF 1-29?
- What is the difference between DAC and no-DAC CJC-1295?
- Does Ipamorelin raise cortisol?
- Why are CJC-1295 and Ipamorelin blended together?
- How long is the half-life of CJC-1295 with DAC?
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.
- PubChemPubChem · DAC:GRF (CID 56841945)pubchem.ncbi.nlm.nih.gov
- PubChemPubChem · Sermorelin (CID 16132413)pubchem.ncbi.nlm.nih.gov
- PubChemPubChem · CJC-1295 (CID 91971820)pubchem.ncbi.nlm.nih.gov
- PubMedTeichman et al., Prolonged stimulation of GH & IGF-I by CJC-1295. J Clin Endocrinol Metab 2006 (PMID 16352683)pubmed.ncbi.nlm.nih.gov
- PubMedRaun et al., Ipamorelin, the first selective GH secretagogue. Eur J Endocrinol 1998 (PMID 9849822)pubmed.ncbi.nlm.nih.gov
- PubMedMüller TD et al., Ghrelin. Molecular Metabolism 2015 (PMID 26042199)pubmed.ncbi.nlm.nih.gov
- PubChemPubChem · Ipamorelin (CID 9831659)pubchem.ncbi.nlm.nih.gov
- TrialClinicalTrials.gov · GH-secretagogue trialsclinicaltrials.gov
- GuidelineGoogle: Creating helpful, reliable, people-first contentdevelopers.google.com
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.
More CJC-1295 & Ipamorelin articles
- Half-Life: Why a Covalent Bond Changes EverythingMinutes for native GHRH, about thirty for Mod GRF, days for the DAC form. Each step is a specific chemical intervention against a specific clearance route.
- What Is Ipamorelin? Sequence, Receptor and SelectivityIpamorelin is a five-residue ghrelin receptor agonist, Aib-His-D-2-Nal-D-Phe-Lys-NH2, described as the first selective growth hormone secretagogue.
- Ipamorelin Sequence and Chemical IdentityAib-His-D-2-Nal-D-Phe-Lys-NH2, CAS 170851-70-4, CID 9831659, 711.9 Da. One name, one compound — unusually clean for this field.
- Ipamorelin Molecular Weight and Physical Properties711.9 Da for C38H49N9O5 — high mass for five residues, because two of them carry aromatic ring systems. What that composition implies.
- How Ipamorelin Acts at the Ghrelin ReceptorGHS-R1a is the ghrelin receptor. Ipamorelin agonises it selectively, releasing GH without the cortisol and prolactin effects of earlier secretagogues.
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