Quick answer: Tesamorelin is a 44-residue GHRH analog with an N-terminal acyl cap (about 5,136 Da). CJC-1295 no DAC is a 29-residue analog with four amino acid substitutions (about 3,368 Da). Both act at the GHRH receptor, but they differ in size, stabilization and published record. A measured mass is what separates them on a certificate; a purity percentage cannot.
Two GHRH analogs built for different jobs
Tesamorelin and CJC-1295 are both analogs of growth hormone-releasing hormone (GHRH), and both turn up in catalogs of pituitary-axis research peptides. Buyers often file them together, yet they are different molecules with different sizes, different stabilizing changes and different literature behind them. Assuming they are interchangeable is the quickest way to write the wrong name into a protocol.
This guide compares the two on origin, structure, the way each was stabilized, what the published work reports, and the checks a certificate should support. The CJC-1295 discussed here is the version without a drug affinity complex (CJC-1295 no DAC, also called modified GRF 1-29). It is background for laboratory research use only. Nothing below describes an effect or a use in people or animals. Single-compound background is in the tesamorelin research overview and the CJC-1295 no DAC research overview.
Origin: the full-length hormone versus the short active fragment
Native human GHRH is a 44-residue peptide made in the hypothalamus. It binds the GHRH receptor on pituitary somatotroph cells. Early structure work showed that most of the receptor activity sits in the first 29 residues, which led to the short analog sermorelin, GRF(1-29). Sermorelin works in assays but is broken down quickly by the enzyme dipeptidyl peptidase IV, which clips the first two residues.
The two peptides in this guide took different routes from that starting point. Tesamorelin keeps the full 44-residue sequence and adds a small chemical group to the front end. CJC-1295 no DAC keeps only the 29-residue fragment and swaps four amino acids inside it. One approach protects the original length; the other rebuilds a short fragment into a sturdier one. A broader look at the shorter parent is in the sermorelin overview.
Side-by-side comparison
| Feature | Tesamorelin | CJC-1295 no DAC (modified GRF 1-29) |
|---|---|---|
| Parent hormone | GHRH | GHRH |
| Length | 44 residues (full length) | 29 residues (fragment) |
| Stabilizing change | trans-3-hexenoyl cap on N-terminal Tyr | D-Ala2, Gln8, Ala15, Leu27 substitutions |
| Approximate mass | About 5,136 Da | About 3,368 Da |
| Receptor | GHRH receptor | GHRH receptor |
| Albumin-binding linker | No | No (the DAC version has one) |
| Key identity check | Measured mass near 5,136 Da | Measured mass near 3,368 Da |
| Listed by V8 | Yes, for research use only | Yes, for research use only |
Structure and stabilization
Tesamorelin is GHRH(1-44) carrying a trans-3-hexenoyl group on the N-terminal tyrosine. That acyl cap makes the front of the molecule harder for dipeptidyl peptidase IV to remove, while the rest of the sequence stays the same as the native hormone. The formula weight is roughly 5,136 Da, which makes it a much larger peptide than most others in a research catalog.
CJC-1295 no DAC, or modified GRF(1-29), has four substitutions relative to the 29-residue fragment: D-alanine at position 2, glutamine at position 8, alanine at position 15 and leucine at position 27. The D-alanine blocks the cleavage site for dipeptidyl peptidase IV, and the other changes were chosen to improve stability of the chain. Its mass is about 3,368 Da. Because it is a 29-residue chain with no attached group, it is a simpler molecule to characterize than tesamorelin.
The naming trap is the DAC. The related compound CJC-1295 with DAC adds a reactive linker intended to bind serum albumin, and the published pharmacokinetics describe a much longer persistence than the no-DAC version. Those papers do not describe the no-DAC peptide, so a reader quoting them for a no-DAC vial is quoting the wrong molecule. The CJC-1295 DAC vs. no DAC comparison covers that split in detail.
What the published work reports
Tesamorelin has a large published record, much of it from clinical programs. That literature is outside the scope of a research-use catalog, and this guide does not summarize or rely on it. The point for a bench scientist is narrower: the compound is well characterized, has a defined structure, and appears in the literature under one consistent name.
For CJC-1295, the foundational papers describe the DAC version bound to albumin, and one 2006 paper from Ionescu and Frohman examined how pituitary secretion patterns behaved under continuous stimulation by a long-acting analog. Research on the no-DAC peptide is usually framed as a comparison with sermorelin or with other secretagogues, since all of them act at the same receptor. In both cases, the receptor is the GHRH receptor, so design questions often turn on pharmacokinetic behavior and on the exact reagent used rather than on a different target.
The sensible reading for a buyer is that the two share a receptor and differ in size, chemistry and evidence base. A design that cites a paper on one cannot swap in the other without saying so.
What a certificate should show
Size is the first identity check. A 44-residue peptide near 5,136 Da and a 29-residue peptide near 3,368 Da are far apart, so a measured mass from a mass spectrometer separates them at once. A report that lists only HPLC purity cannot do that, because both can give a single clean peak. Look for a measured mass next to the expected mass, the exact compound name, and a lot identifier and test date that match the vial. For background on reading these documents, see understanding HPLC purity and how to read a COA.
Truncation and deletion products are the main impurity concern for longer chains. Tesamorelin has 44 coupling steps, and each step can leave a small population of shortened sequences, so a purity figure is worth reading together with the chromatogram. For cell work, look for an endotoxin result and a sterility statement as well.
V8 Peptides publishes certificates for only some products. Where one exists, it reports HPLC purity and identity, endotoxin and PCR sterility. This article describes general buyer practice and is not a statement about any particular lot. Product listings are at tesamorelin and CJC-1295 no DAC. Compound-specific pages are tesamorelin purity testing and CJC-1295 no DAC purity testing, and sourcing checklists are in where to buy tesamorelin and where to buy CJC-1295 no DAC.
Handling and record keeping
Both arrive as lyophilized powder and should be kept cold, dry and away from light until use, with the opening date written on the vial. Longer peptides can be more sensitive to repeated handling, so a lab should plan its aliquots before opening a vial. Storage details for tesamorelin are in the tesamorelin storage guide. This guide gives no volumes or concentrations, because those belong in a laboratory's own validated procedure.
In the notebook, record the exact compound name, whether DAC is present, lot, supplier, certificate date and storage conditions. When comparing the two, run them as separate reagents with separate controls. A related comparison of the shorter parent is in tesamorelin vs. sermorelin.
Frequently asked questions
Are tesamorelin and CJC-1295 the same kind of peptide?
They are both GHRH analogs that act at the GHRH receptor, but they are different molecules. Tesamorelin is a 44-residue chain with an N-terminal cap. CJC-1295 no DAC is a 29-residue chain with four amino acid substitutions.
How different are they in size?
Tesamorelin is about 5,136 Da and CJC-1295 no DAC is about 3,368 Da, a gap of roughly 1,770 Da that any mass measurement would catch.
Which one is closer to native GHRH?
Tesamorelin keeps the full 44-residue sequence and adds one acyl group. CJC-1295 no DAC is a short fragment with several amino acid changes.
What does DAC mean?
It stands for drug affinity complex, a linker that binds albumin in the DAC version of CJC-1295. The no-DAC peptide does not have it, so papers on the DAC form do not describe it.
Why does the D-alanine matter?
It sits at the position where dipeptidyl peptidase IV cleaves, so it blocks that cut. Tesamorelin protects the same end with an acyl cap instead.
Can HPLC purity tell me which peptide is in the vial?
Not on its own. Both can show one clean peak. A measured mass next to the expected mass is the identity check.
Why are longer peptides harder to verify?
Each coupling step in synthesis can leave shortened sequences, so a 44-residue chain has more places for deletion products to arise. Read the chromatogram, not just the percentage.
Does V8 sell both?
Yes, both are listed for laboratory research use only.
Does this article describe a use in people?
No. It summarizes structure, published background and analytical practice. Neither product is sold for human or animal consumption.
What should I record for each vial?
The exact compound name, whether DAC is present, lot identifier, certificate date, supplier, storage conditions and the date the vial was opened.
References
- Ionescu M, Frohman LA. Pulsatile secretion of growth hormone (GH) persists during continuous stimulation by CJC-1295, a long-acting GH-releasing hormone analog. J Clin Endocrinol Metab. 2006;91(12):4792-4797.
- Jette L, Leger R, Thibaudeau K, et al. Human growth hormone-releasing factor (hGRF)1-29-albumin bioconjugates activate the GRF receptor on the anterior pituitary in rats: identification of CJC-1295 as a long-lasting GRF analog. Endocrinology. 2005;146(7):3052-3058.
- Spooner LM, Olin JL. Tesamorelin: a growth hormone-releasing factor analogue for HIV-associated lipodystrophy. Ann Pharmacother. 2012;46(2):240-247.