CJC-1295 with DAC and CJC-1295 without DAC are often discussed as if they were two names for the same thing, but in the research literature they are two distinct compounds built on a shared peptide backbone. The difference is not the sequence that does the work. The difference is a small piece of chemistry, the Drug Affinity Complex, that changes how long the molecule stays intact in circulation.

That single distinction governs how each form behaves as a research tool, which is why Janera Science, like the study designs and published papers behind these compounds, treats them as separate materials. This article stays on the chemistry: what the DAC modification is, how it extends half-life through albumin binding, and why the no-DAC variant remains a separate compound in its own right.

This content is provided for informational and educational purposes only and does not constitute medical, pharmaceutical, or legal advice. The products discussed are intended for laboratory research purposes only and are not for human or animal consumption. They are not intended to diagnose, treat, cure, or prevent any disease.

Two Compounds, One Backbone: What CJC-1295 Actually Is

CJC-1295 is a synthetic analogue of growth hormone-releasing hormone (GHRH), a signalling peptide that the body uses to prompt the pituitary gland. Native GHRH is a 44-residue peptide, but its first 29 residues, written as hGRF(1-29), retain the receptor activity, which is why both forms of CJC-1295 are built on that shorter scaffold (Endocrinology, 2005).

The hGRF(1-29) scaffold on its own degrades quickly in plasma. To slow that down, CJC-1295 carries four amino acid substitutions, at positions 2, 8, 15, and 27, which is why it is described as a tetrasubstituted analogue. These substitutions, D-Ala at position 2, Gln at position 8, Ala at position 15, and Leu at position 27, confer resistance to dipeptidyl peptidase-IV (DPP-IV) and other plasma proteases without abolishing the peptide's affinity for the GHRH receptor (Endocrinology, 2005).

Here is the part that causes most of the confusion. This tetrasubstituted backbone is the same in both products. CJC-1295 without DAC, also catalogued as Modified GRF (1-29) or Mod GRF 1-29, is that backbone and nothing more. CJC-1295 with DAC is that same backbone plus one additional chemical feature.

So the two compounds are not different sequences targeting different pathways. They are the same modified GHRH analogue, distinguished by whether the Drug Affinity Complex has been added.

The Drug Affinity Complex (DAC): The Chemistry of the Albumin Tether

The Drug Affinity Complex is a small reactive appendage attached to the peptide, engineered to grab onto a protein already circulating in the bloodstream. In CJC-1295 with DAC, the appendage is an N-epsilon-3-maleimidopropionamide derivative of lysine added at the C-terminus of the tetrasubstituted hGRF(1-29) backbone (Endocrinology, 2005). Both the backbone substitutions and this terminal group are installed during peptide synthesis, before any albumin is involved.

The working part of that appendage is the maleimide group. A maleimide is a soft electrophile that reacts selectively with free thiols, and serum albumin offers a convenient target: a single unpaired cysteine, Cys34, whose thiol is unusually reactive under physiological conditions (ConjuChem). When the maleimide meets that thiol, it forms a stable covalent thioether bond, tethering the peptide to albumin.

The platform behind this, ConjuChem's DAC technology, frames the construct in three parts: the active peptide, a linker, and the reactive maleimide group at the far end of the linker (ConjuChem). The covalent attachment is described as permanent, meaning the peptide does not need to detach from albumin to remain active.

The key chemical insight is that the DAC turns a free-floating peptide into a peptide bolted to a long-lived carrier protein. Everything that follows about half-life is downstream of that one bond.

How Albumin Binding Extends the Half-Life

A free peptide in plasma faces two fast exits: enzymatic cleavage and filtration by the kidneys. Small peptides are cleared rapidly on both counts, which is why the unmodified hGRF(1-29) scaffold is degraded almost as quickly as it appears (Endocrinology, 2005).

Binding to albumin changes that arithmetic. Albumin is a large protein with a long circulating half-life, reported at roughly 15 days in humans, and it is too big to be filtered freely by the kidney (ConjuChem). By covalently attaching to albumin, the peptide inherits that protection: it is shielded from proteases and from rapid renal clearance, so it persists far longer.

The measured difference is dramatic. In the discovery work that identified CJC-1295, the albumin-bound compound was still detectable in plasma beyond 72 hours in rat models, whereas the unconjugated scaffold cleared quickly (Endocrinology, 2005). In a later set of two randomized, placebo-controlled human trials, researchers estimated the circulating half-life of CJC-1295 with DAC at approximately 5.8 to 8.1 days (J Clin Endocrinol Metab, 2006).

That same study documented how long the compound's signalling persisted in the study cohort: plasma growth hormone rose roughly two- to ten-fold for six or more days, and IGF-1 rose roughly 1.5- to three-fold for nine to eleven days (J Clin Endocrinol Metab, 2006). The headline number researchers cite is straightforward: a covalent tether to a 15-day carrier protein converts a peptide that lasts minutes into one that registers for days. You can review what purity and identity verification look like for compounds like these on our lab results page.

Why the No-DAC Variant Exists as a Separate Research Compound

If the DAC version lasts so much longer, a reasonable question is why the no-DAC form is still made and catalogued separately. The answer is that long half-life and short half-life are not better or worse in the abstract. They are different signalling profiles, and each is useful for studying different questions.

CJC-1295 without DAC clears on a timescale of minutes, which produces a brief, transient activation of the GHRH receptor. CJC-1295 with DAC produces sustained activation lasting days. The human trial data make the contrast concrete: increases in growth hormone and IGF-1 were sustained over many days rather than minutes (J Clin Endocrinol Metab, 2006).

For laboratory work, that distinction matters. A short-acting analogue lets researchers study acute, reversible responses and rhythm, while a long-acting analogue lets them study what happens under prolonged receptor engagement. Animal-model research has used the long-acting form to examine sustained GHRH-receptor activation over time, including a study in which CJC-1295 normalized growth in a GHRH knockout mouse model (Am J Physiol Endocrinol Metab, 2006).

So the no-DAC variant is not a discount version of the DAC compound. It is a distinct research tool whose value is precisely its short duration of action, and that is why Janera Science lists it as its own item rather than a substitute.

Side by Side: A Chemistry-First Comparison

The table below summarizes the documented differences between the two forms. Every entry refers to molecular structure and pharmacokinetics, the properties that define each compound as a research material.

The four backbone substitutions, the maleimide-to-Cys34 bond, and the resulting half-life figures are the load-bearing facts here. Confirming those structural and purity details for any given batch is what a Certificate of Analysis is for, and at Janera Science it is the document that lets a researcher verify they have the form they intended to order. For broader context on how peptide chemistry is reported in the literature, our published research category collects related material.

Frequently Asked Questions

What is the difference between CJC-1295 with DAC and without DAC?

Both compounds share the same tetrasubstituted hGRF(1-29) backbone, a modified GHRH analogue. CJC-1295 with DAC adds a maleimide-bearing lysine group at the C-terminus that covalently binds serum albumin, extending the circulating half-life to roughly 5.8 to 8.1 days. CJC-1295 without DAC lacks that feature and clears within minutes (J Clin Endocrinol Metab, 2006).

What does DAC stand for in CJC-1295?

DAC stands for Drug Affinity Complex. It is a chemical construct of three parts: the active peptide, a linker, and a reactive maleimide group that bonds to a thiol on serum albumin, allowing the peptide to attach to a long-lived carrier protein (ConjuChem).

Is CJC-1295 without DAC the same as Modified GRF (1-29)?

Yes. CJC-1295 without DAC, Modified GRF (1-29), and Mod GRF 1-29 all refer to the same molecule: the first 29 residues of GHRH with four stabilizing substitutions and no albumin-binding complex.

Why does the DAC version last so much longer?

Albumin is a large plasma protein with a circulating half-life of about 15 days in humans, and it resists rapid kidney filtration (ConjuChem). By covalently binding to albumin, the DAC-modified peptide is protected from enzymatic breakdown and clearance, so it persists for days rather than minutes (Endocrinology, 2005).

What is the role of the maleimide group?

The maleimide is a soft electrophile that reacts selectively with free thiols. Serum albumin carries one highly reactive free thiol at Cys34, so the maleimide forms a stable covalent bond there, anchoring the peptide to albumin (ConjuChem).

What does "Research Use Only" mean?

Research Use Only (RUO) indicates that a product is intended exclusively for laboratory research purposes. RUO materials are not approved for human or animal use and are not intended to diagnose, treat, cure, or prevent any disease. You can read more in our frequently asked questions.

Key Takeaways

• CJC-1295 with DAC and without DAC share the same tetrasubstituted hGRF(1-29) backbone; the only structural difference is the albumin-binding Drug Affinity Complex.

• The DAC is a maleimide-bearing lysine group that forms a covalent bond with the Cys34 thiol of serum albumin (Endocrinology, 2005).

• Binding to albumin, a carrier protein with a roughly 15-day circulating half-life, protects the peptide from enzymatic and renal clearance (ConjuChem).

• Published human trial data estimate the DAC form's half-life at approximately 5.8 to 8.1 days, versus minutes for the unmodified backbone (J Clin Endocrinol Metab, 2006).

• The no-DAC variant is a separate research compound, valued for its short, transient signalling profile rather than treated as a substitute for the long-acting form.