CJC-1295 DAC: Drug Affinity Complex Chemistry and Research Applications

CJC-1295 DAC is a synthetic analogue of growth hormone-releasing hormone (GHRH) that carries an additional chemical modification known as a Drug Affinity Complex. That single modification is the reason the compound occupies its own place in the laboratory literature rather than being treated as a variant of standard CJC-1295. Researchers investigating the somatotropic axis frequently need to distinguish between the two forms, because the pharmacokinetic profile they produce in preclinical models is substantially different.

This article examines the structural chemistry of CJC-1295 DAC, the albumin-binding mechanism that defines it, how it compares with non-DAC GHRH analogues, and the handling and purity considerations relevant to any laboratory sourcing the compound. All material below is presented for scientific and educational reference only.

What Is CJC-1295 DAC?

CJC-1295 is a tetrasubstituted 30-amino-acid peptide derived from the biologically active 1–29 fragment of human growth hormone-releasing hormone. Native GHRH(1–29), also known as sermorelin, is a functional but fragile molecule: circulating dipeptidyl peptidase-4 (DPP-4) cleaves it within minutes, which places a hard ceiling on how long it can occupy its receptor in an experimental system.

CJC-1295 addresses that fragility with four amino acid substitutions along the backbone:

• D-Ala at position 2 — blocks the DPP-4 cleavage site that degrades native GHRH almost immediately after release.
• Gln at position 8 — reduces asparagine deamidation, a common degradation route in aqueous solution.
• Ala at position 15 — improves binding affinity at the GHRH receptor.
• Leu at position 27 — prevents methionine oxidation, which otherwise reduces stability during storage and handling.

Those four changes produce what is often catalogued as Modified GRF (1-29). The DAC designation refers to a further addition: a maleimidopropionyl lysine linker attached at the C-terminus of the peptide chain. This linker is the Drug Affinity Complex, and it is what separates CJC-1295 DAC from every other GHRH analogue in the category.

The Drug Affinity Complex Mechanism

The maleimido group carried by the DAC linker is chemically reactive toward free thiol groups. In serum, the most abundant available thiol is the cysteine-34 residue of albumin — a residue that sits exposed on the surface of the most plentiful protein in circulation. When CJC-1295 DAC encounters albumin, the maleimide forms a stable covalent thioether bond with that cysteine residue.

The consequence is a bioconjugate: the peptide is no longer a free-floating 30-residue chain subject to rapid renal filtration and enzymatic breakdown, but a passenger attached to a 66 kDa carrier protein with a circulating half-life measured in weeks. Published pharmacokinetic work in preclinical and early clinical models has reported terminal half-life values for CJC-1295 DAC in the range of roughly six to eight days, against minutes for unmodified GHRH(1–29).

For researchers, the relevance is methodological rather than promotional. Albumin conjugation is a well-characterised half-life extension strategy used across the wider peptide therapeutics field, and CJC-1295 DAC is one of the clearest illustrations of it in the growth hormone secretagogue class. It allows study designs that would otherwise require continuous infusion to be conducted with far less frequent administration in the model system.

Receptor Signalling in Research Models

Regardless of the DAC modification, the peptide acts on the same target as native GHRH: the GHRH receptor (GHRHR), a class B G-protein-coupled receptor expressed on somatotroph cells of the anterior pituitary. The downstream sequence documented in the literature runs as follows:

• Ligand binding activates the receptor and its associated Gs alpha subunit.
• Adenylate cyclase is stimulated, raising intracellular cyclic AMP.
• Elevated cAMP activates protein kinase A.
• PKA phosphorylates CREB, which drives transcription of the growth hormone gene and of Pit-1.
• Somatotroph proliferation and growth hormone synthesis increase, alongside release of stored hormone.
• Circulating growth hormone acts on hepatic tissue to stimulate IGF-1 production.

An important distinction studied in the literature is the difference between pulsatile and sustained receptor occupancy. Endogenous GHRH is released in discrete pulses, and the somatotropic axis is regulated by counter-pulses of somatostatin. A long-acting analogue that occupies the receptor continuously produces a different signalling pattern — sometimes described in research discussion as a sustained elevation or “bleed” — rather than amplifying the natural pulse architecture. Investigators comparing DAC and non-DAC forms are frequently studying precisely this question, since the two produce measurably different profiles of feedback inhibition and receptor desensitisation in model systems.

CJC-1295 DAC vs Non-DAC Analogues

The table below summarises the structural and kinetic distinctions most often referenced when selecting between forms for a study design.

Neither form is inherently superior; they answer different experimental questions. Work aimed at reproducing physiological pulsatility generally favours the non-DAC form, while work examining sustained axis stimulation, receptor downregulation, or long-interval dosing intervals favours the DAC variant. Our overview of the base compound at /cjc-1295-peptide/ covers the non-DAC form in more detail.

Combination Research Protocols

CJC-1295 DAC is frequently examined alongside growth hormone secretagogue receptor (GHS-R1a) ligands such as ipamorelin. The rationale is mechanistic complementarity: GHRH analogues act through the GHRH receptor and cAMP/PKA signalling, while ghrelin mimetics act through GHS-R1a and the phospholipase C / inositol trisphosphate pathway, additionally suppressing somatostatin tone. Because the two pathways converge on the same somatotroph population from different directions, co-administration in model systems has been studied as a way of examining synergistic versus additive receptor responses.

It is worth noting that many combination studies use the non-DAC form rather than the DAC form, precisely because ipamorelin is short-acting and pairing it with a multi-day analogue creates mismatched exposure windows. Researchers designing such work should account for that asymmetry. Our dedicated article at /cjc-1295-with-ipamorelin/ examines the combination in more depth, and /ipamorelin-peptide/ covers the secretagogue on its own.

Laboratory Handling, Reconstitution and Storage

CJC-1295 DAC is supplied as a lyophilised white powder under vacuum. Because the DAC linker is chemically reactive, handling discipline matters more here than with a plain peptide chain — the maleimide group can be consumed by any stray thiol in the environment, quietly reducing the effective conjugating fraction of the sample.

Recommended laboratory practice

• Storage of lyophilised material: keep sealed vials at -20 °C, protected from light. Short transit at ambient temperature is tolerated by the lyophilised form.
• Reconstitution: introduce diluent slowly down the inner vial wall rather than directly onto the powder cake, and swirl gently. Vortexing shears peptide chains.
• Avoid thiol-containing diluents: reducing agents such as DTT or beta-mercaptoethanol will react with the maleimide group and destroy the DAC function.
• Post-reconstitution storage: hold at 2–8 °C and use within a short working window; aliquot before freezing.
• Freeze-thaw cycling: each cycle degrades peptide integrity. Aliquot into single-use volumes at the point of reconstitution.
• Documentation: record lot number, reconstitution date, diluent, and concentration for every aliquot to preserve experimental reproducibility.

Our general guidance on lyophilised material at /lyophilized-peptides/ and on laboratory workflow at /handling-research-peptides/ applies equally here.

Purity, Verification and Sourcing

Analytical verification is not optional for a compound of this type. Because the DAC linker adds a reactive moiety, a sample may test as chemically present while carrying a significant fraction of hydrolysed or pre-reacted linker that will never conjugate to albumin. A supplier certificate should therefore report more than a single purity figure.

• HPLC purity: reverse-phase chromatography establishing the proportion of the target species, typically specified at 98 percent or higher for research-grade material.
• Mass spectrometry: confirms the molecular weight matches the expected mass including the DAC linker, distinguishing DAC from non-DAC product.
• Batch traceability: a certificate of analysis tied to the specific lot number on the vial, not a generic document.
• Appearance and solubility: a uniform white cake, free of discolouration or collapse indicating a compromised vacuum seal.

Meta Molecule publishes lot-linked documentation for its catalogue; see /certificates-of-analysis/ and our explainer at /understanding-peptide-purity/ for how to read these reports.

Sourcing and regional supply considerations

Researchers searching for a supplier in their own region are usually solving a practical problem rather than a scientific one: transit time, customs handling, and cold-chain integrity all degrade with distance. Domestic dispatch shortens the window in which a temperature-sensitive lyophilised product sits in an uncontrolled environment, and it removes the customs delays that frequently strand international peptide shipments for days. Laboratories, universities, and independent research facilities across the United States generally find that a domestic supplier with in-country warehousing offers more predictable lead times and simpler documentation than an overseas manufacturer, even where the underlying synthesis quality is comparable. Meta Molecule ships domestically with lot documentation included at dispatch.

Frequently Asked Questions

• What does DAC stand for in CJC-1295 DAC?

DAC stands for Drug Affinity Complex. It refers to a maleimidopropionyl lysine linker attached to the C-terminus of the peptide, which forms a covalent bond with cysteine-34 on serum albumin and substantially extends the compound’s circulating half-life in model systems.

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

Both share the same four backbone substitutions. The DAC version carries an additional albumin-binding linker, giving it a reported half-life of several days rather than roughly thirty minutes. The non-DAC form is generally used in protocols designed to mimic natural pulsatile signalling; the DAC form suits long-interval study designs.

• Is CJC-1295 DAC the same as sermorelin?

No. Sermorelin is the native, unmodified GHRH(1–29) sequence and is degraded within minutes by DPP-4. CJC-1295 DAC is a modified analogue with four amino acid substitutions plus the albumin-binding linker. They share a receptor target but differ substantially in stability. Our comparison at /sermorelin-peptide-vs-tesamorelin/ covers related GHRH analogues.

• How should CJC-1295 DAC be stored in a laboratory setting?

Lyophilised vials should be held at -20 °C, sealed and shielded from light. After reconstitution with an appropriate diluent, material should be refrigerated at 2–8 °C, aliquoted into single-use volumes, and protected from repeated freeze-thaw cycles. Thiol-containing reducing agents must be avoided, as they react with the DAC linker.

• Can CJC-1295 DAC be purchased for personal use?

No. CJC-1295 DAC is supplied strictly as a research chemical for in-vitro and non-human laboratory investigation. It is not approved for human consumption, is not a dietary supplement, and is sold only to qualified researchers and institutions who accept responsibility for lawful handling and disposal.

Related Reading From Meta Molecule

• CJC-1295 Peptide Overview — the non-DAC form, its structure and research context.
• CJC-1295 with Ipamorelin — mechanistic rationale behind the studied combination.
• Ipamorelin Peptide — selective GHS-R1a ligand profile and research background.
• Sermorelin vs Tesamorelin — how other GHRH analogues compare on stability and structure.
• Understanding Peptide Purity — how to read HPLC and mass spectrometry data on a COA.
• Certificates of Analysis — lot-linked analytical documentation for the Meta Molecule catalogue.

RESEARCH USE ONLY — LEGAL DISCLAIMER
All compounds referenced on this page are supplied strictly as laboratory chemicals for in-vitro research and non-human laboratory investigation. They are not drugs, foods, cosmetics, or dietary supplements, and they are not intended to diagnose, treat, cure, or prevent any disease or condition in humans or animals. No statement on this page constitutes medical advice or a recommendation for human or veterinary use. Purchase is restricted to qualified researchers, licensed institutions, and laboratory professionals who accept full responsibility for lawful handling, storage, and disposal in accordance with all applicable local, state, national, and international regulations. Meta Molecule does not supply these materials for personal use of any kind.

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