Sermorelin vs CJC-1295 No DAC: Native GHRH(1-29) Against Its Hardened Analogue

Sermorelin is an exact copy of the natural GHRH(1-29) sequence, whereas CJC-1295 without DAC takes those 29 residues and deliberately replaces four of them. Positions 2, 8, 15 and 27 are altered to close off three specific breakdown routes: DPP-4 cleavage, asparagine deamidation and methionine oxidation. Together they add a mere 10 g/mol, taking the mass from 3357.93 to 3367.93 g/mol. So the choice between sermorelin and CJC-1295 no DAC hinges on whether your protocol wants the native sequence as its biological reference point, or an analogue toughened enough to come through handling and assay conditions chemically intact.

We supply sermorelin and CJC-1295 (No DAC / Mod GRF 1-29) as freeze-dried powder in 10, 5 and 2 mg vials, each with a certificate matched to its lot, in the GHRH analogs category. Both are research chemicals restricted to in-vitro and preclinical laboratory work.

The same receptor, the same fragment, one reinforced variant

It has been known in endocrinology for decades that essentially all of the hormone's receptor-binding capacity resides in the first 29 of its 44 residues, which is why laboratories standardised on GHRH(1-29) instead of the complete hormone. Sermorelin is precisely that fragment: the natural sequence, amidated at the C-terminus, with no other changes at all.

Modified GRF 1-29 — marketed widely as CJC-1295 without DAC — is an engineered version of the identical fragment. None of its four substitutions is intended to alter how the peptide talks to its receptor; each is a fix for a specific chemical weakness, and understanding them individually accounts for nearly all the practical differences between the two products.

Position 2: blocking DPP-4 cleavage

Native GHRH loses its first two amino acids to dipeptidyl peptidase-4 within a few minutes, and that destroys the N-terminal region the receptor relies on. Putting a D-amino acid at position 2 physically prevents the enzyme from making the cut. In any experiment run in serum, plasma or a tissue preparation that retains peptidase activity, this substitution is the one that matters most: across a long incubation, the analogue survives while sermorelin visibly degrades.

Position 8: removing a deamidation site

In aqueous solution, asparagine slowly converts to aspartate on its own, adding 1 Da and altering the molecule's charge. Replacing the asparagine that sits at position 8 removes that possibility. One dalton is easy to overlook when reading a mass spectrum, but the product is a different chemical species with different isoelectric properties.

Position 15: stabilising the fold

Rather than blocking a named degradation reaction, the substitution at position 15 is reported to strengthen the helical structure that the peptide adopts.

Position 27: getting rid of methionine

You can spot this change simply by comparing molecular formulas: sermorelin contains one sulfur atom and the analogue contains none, because its methionine has been exchanged. Methionine is the residue most easily oxidised in stored peptides, becoming the sulfoxide and gaining 16 Da when exposed to oxygen, light, metal traces and time. Its removal takes away the compound's principal storage liability.

What this means when designing experiments

Since the receptor is untouched by all four substitutions, both peptides serve the same purposes: probing signalling at the pituitary GHRH receptor, measuring cAMP accumulation, and studying pulsatile growth hormone release in whole-animal preparations. The difference lies in how much of the compound is still the compound by the time you read the result.

For brief in-vitro experiments in a clean defined buffer, the two are close to equivalent, and there is a good argument for sermorelin: its sequence is the one the receptor actually evolved with. Once experiments run longer, involve serum, or rely on a single stock solution over several weeks, the analogue is the safer bet simply because it has fewer chemical exits available to it.

What makes sermorelin's decay awkward is that what it turns into is not inactive: an oxidised or deamidated molecule is still a peptide, still comes off the column near the parent, and may retain some fraction of its activity. A gradual decline in potency across a long study therefore looks like a biological finding when in fact it is a chemistry problem. Labs relying on sermorelin for extended periods ought to re-analyse the stock rather than assume it has stayed put.

Matching the compound to the question

Sermorelin as the reference ligand

Where the design requires the natural ligand — setting baseline receptor pharmacology, producing a reference concentration–response curve, or providing the standard against which analogues are judged — sermorelin is the material to use. It is equally appropriate for reproducing older endocrine papers, which almost always worked with the native fragment. Sermorelin also carries a regulatory past that few research peptides do not: a prescription product based on it was once sold in the United States and has since been taken off the market. That applies to the pharmaceutical article, however, and not to research-grade powder.

Modified GRF 1-29 as the everyday workhorse

Whenever serum is present, protocols run for weeks in animals, stock solutions are kept in use for a long time, or breakdown would blur the endpoint, the modified peptide is the more robust choice. It is also the standard comparator in structure–activity work examining how much alteration a GHRH fragment tolerates before receptor behaviour changes.

Both together, when stability is what you are measuring

The two make a neat two-member series: identical receptor, identical chain length, four specified substitutions between them. Run side by side under matched conditions, they let you distinguish genuine pharmacological differences from differences in how well each compound lasts through the assay. The series can be taken further — tesamorelin adds a trans-3-hexenoyl group to the N-terminus of the same fragment (see tesamorelin vs sermorelin), and CJC-1295 with DAC adds covalent albumin binding on top of the same four substitutions.

Combining with a ghrelin-receptor secretagogue

GHRH analogues and ghrelin-receptor secretagogues act on separate receptors, which is why studies so often use them together. Alongside ipamorelin on its own for single-agent arms, we offer ready-mixed vials of sermorelin plus ipamorelin and of CJC-1295 plus ipamorelin; the secretagogue landscape overview explains how the family fits together.

Handling, reconstitution and storage

Standard peptide practice covers both: store the sealed freeze-dried vial in the freezer, let it come up to room temperature before the stopper is pierced so that no water condenses on chilled powder, add diluent along the inside wall of the vial, allow it to dissolve without shaking, and split the stock into aliquots so nothing is frozen and thawed over and over.

Sermorelin needs more care within that routine, and the reason is its methionine. Oxygen in solution, light exposure and trace metals all accelerate oxidation, so make sermorelin solutions up fresh, keep them in the dark, and avoid leaving them in tubes with a large air space above the liquid. Deamidation is accelerated by base, so extended storage in an alkaline buffer is also best avoided. None of these concerns applies meaningfully to the modified analogue.

The following is bench arithmetic, not a usage recommendation: 5 mg dissolved in 2 mL of diluent yields 2.5 mg/mL — 2,500 mcg/mL — meaning 250 mcg per 0.1 mL. Because only 10 g/mol (roughly 0.3 percent) separates the two molecular weights, a mass concentration is essentially a molar concentration for either peptide, so matching molar exposure across arms is unusually straightforward. The reconstitution and storage guides give the full procedure.

Purity, identity and certificate checks

Request the certificate tied to each vial's lot, and check HPLC purity with the visible chromatogram, a mass-spec result agreeing with theory — sermorelin 3357.93 g/mol, the analogue 3367.93 g/mol — and a lot number matching the label. On a sermorelin certificate, look specifically for a small peak 16 Da heavier than the parent (methionine sulfoxide) and for a 1 Da increase (deamidation); both turn up frequently in older stock and neither is visible in a purity percentage. For the analogue, the definitive identity marker is that its formula contains no sulfur, which separates it unambiguously from the native fragment. What a complete certificate should include is set out in our COA guide.

Regulatory framing

Both peptides are sold exclusively as research chemicals for laboratory use. Modified GRF 1-29 has no approved status anywhere. The US prescription history of sermorelin concerns a pharmaceutical product that has been discontinued, and that status belongs to the regulated article rather than to research-grade powder. Further context is available in our growth and performance research overview.