This is the rare compound whose common name describes a part it does not have. Understanding what DAC is, and what its absence changes, is most of what you need to read a certificate for this product correctly.

The underlying sequence

The starting point is GHRH(1-29), the first twenty-nine residues of growth hormone-releasing hormone. That fragment is the shortest piece of the natural hormone that still acts at the receptor, which is why analogues are built from it instead of from the full forty-four.

CJC-1295 without DAC is that fragment with four substitutions, usually written as the tetrasubstituted analogue. Each substitution targets a known weakness: the position-two residue that dipeptidyl peptidase IV cleaves, and residues prone to oxidation or isomerisation. (Reference: Mentlein, 1999) The pattern is the same one behind most peptide analogue design, which is to change the chain where it breaks and leave alone the part the receptor reads.

What DAC is

DAC stands for Drug Affinity Complex, a maleimide linker attached to the peptide so that it bonds covalently to albumin in circulation. The published work on CJC-1295 describes that construct, with the linker present. (Reference: Ionescu & Frohman, 2006)

Removing the linker leaves the modified GHRH(1-29) fragment on its own. So the no-DAC product is not a variant of the DAC compound in the sense of a different salt or a different strength: it is a shorter molecule with a different formula, a different mass and a different CAS number. A certificate for one does not describe the other.

Identity on paper

CJC-1295 without DAC is C152H252N44O42, 3367.9 g/mol, CAS 863288-34-0. The CAS number passes the check digit and resolves in PubChem to a record whose formula matches, which is the pair of checks to run: the arithmetic with our validator, then a lookup to read back which substance the number returns.

The formula carries no sulfur, which is itself a readable fact: this molecule has neither methionine nor cysteine, so the oxidation route that matters on methionine-containing peptides does not apply. That is the kind of thing a formula tells you for free.

A sequence calculator cannot produce this mass. Our calculator handles the twenty standard amino acids, and the substitutions here include residues outside that set. It would reject the sequence instead of inventing a mass, which is the correct behaviour and the reason the tool refuses instead of guessing.

Why the naming is a verification problem

A catalogue listing that says only "CJC-1295" is ambiguous between two molecules differing by a linker and roughly a thousand daltons. The way to resolve it is not to trust the product title but to read the certificate: the formula and the measured mass settle which compound is in the vial, and they settle it in a way a name cannot.

This is the general case of something our note on CAS numbers covers. A compound can have several names, and names drift; an identifier and a measured mass do not. When a product's common name is itself ambiguous, the document does the work the label cannot.

What a certificate should show

Purity from RP-HPLC with its conditions, since the column and gradient change the number. Identity from mass spectrometry with observed and theoretical mass shown, which is what distinguishes this compound from the DAC construct. Net peptide content stated separately, because twenty-nine residues purified by reversed-phase chromatography come out as a salt and the powder carries counterion and absorbed water.

Twenty-nine residues means twenty-eight coupling steps in synthesis. That is long enough for deletion sequences to be a real part of the impurity profile, and they sit close to the main peak because they differ from the target by one residue. The chromatogram is worth asking for on a peptide this length.

Why a fragment works at all

That twenty-nine of forty-four residues are enough is a fact about where the receptor reads the molecule. The binding information sits in the N-terminal part of the sequence, so the rest can be removed without losing the interaction. Our note on peptide length covers why a shorter chain is not a weaker version of a longer one.

It also has a practical consequence for anyone buying. A shorter chain is cheaper to synthesise and easier to purify, so a high purity figure on a twenty-nine-mer represents less work than the same figure on a forty-four-mer. Purity percentages are not comparable across lengths, which our note on why prices differ develops.

Storage

The substitutions were chosen partly for stability in circulation, and that is a different question from stability in a vial. A modified residue that resists an enzyme does not resist hydrolysis, deamidation or the ordinary chemistry that proceeds with time and temperature. (Reference: Manning et al., 2010) Our note on storage covers the routes, and the date on a certificate is what lets you place a result in the material's life.

Which receptor

The GHRH receptor, a member of the secretin-like class of G protein-coupled receptors. (Reference: Mayo et al., 2003) That places this compound in a different mechanism from the growth hormone secretagogues, which act at the ghrelin receptor. Our note on secretagogues covers why two compounds associated with the same downstream hormone can act at unrelated receptors.

What the four substitutions are not

They are changes to the chain, not additions to it, so the molecule stays a 29-residue peptide. Nothing is bolted on, no metal is bound, no second chain is attached. That keeps the certificate simple: one sequence, one formula, one mass to compare.

It is worth contrasting with the acylated and linker-carrying analogues in the same family, where the added group is a separate thing to measure and a separate thing to get wrong. Here the whole molecule is amino acids, and the mass measurement covers all of it at once.

Research use only

All products sold by Codex Research are strictly for laboratory research and development. They are not for human or animal consumption and are not intended to diagnose, treat, cure, or prevent any disease.

The compound at Codex Research

CJC-1295 no DAC, 10 mg per vial · batch-verified, with its certificate of analysis.

Frequently asked questions

What does DAC mean in CJC-1295?

Drug Affinity Complex, a maleimide linker attached to the peptide so it bonds covalently to albumin in circulation. The no-DAC product is the peptide without that linker.

Is CJC-1295 no DAC the same compound as CJC-1295?

No. Removing the linker leaves a shorter molecule with a different formula, a different mass and a different CAS number. A certificate for one does not describe the other.

What is the formula and mass of CJC-1295 without DAC?

C152H252N44O42, 3367.9 g/mol, CAS 863288-34-0. The CAS number passes the check digit and resolves in PubChem to a record with a matching formula.

What sequence is it based on?

GHRH(1-29), the first twenty-nine residues of growth hormone-releasing hormone, with four substitutions. That fragment is the shortest piece of the natural hormone that still acts at the receptor.

Why does the absence of sulfur in the formula matter?

It means the molecule has neither methionine nor cysteine, so the methionine oxidation route that adds sixteen mass units does not apply here. A formula tells you that without any further measurement.

Can a sequence calculator give its mass?

No. The substitutions include residues outside the twenty standard amino acids, so a calculator rejects the sequence instead of inventing a mass for it.

References

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