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CJC-1295 comes in two forms, with and without a Drug Affinity Complex moiety. What DAC does, how it changes molecular weight, and handling differences.
CJC-1295 without DAC - also catalogued as Modified GRF (1-29) - is a 29-residue analogue of growth-hormone-releasing hormone carrying four substitutions that improve resistance to enzymatic cleavage relative to native GRF. CJC-1295 with DAC starts from that same 29-residue backbone and adds a lysine at position 30 bearing a Drug Affinity Complex moiety.
Because the two share a backbone, it is tempting to treat them as strengths of the same reagent. Bench protocols do not: the DAC addition changes the molecule's behaviour enough that the two are studied and sourced as distinct materials.
DAC stands for Drug Affinity Complex, a maleimidoproprionic acid moiety attached at the added Lys30 position. It forms a covalent bond with cysteine-34 of serum albumin on contact - that albumin-binding property is the entire functional point of the DAC variant and is absent from the No DAC form.
This is a covalent, irreversible attachment once it occurs, not a reversible binding equilibrium. In any protocol involving serum or albumin-containing media, that distinction changes what the two reagents will do in the system, which is why they cannot be treated as interchangeable strengths of one compound.
The No DAC form has a molecular weight of roughly 3367.9 g/mol; the DAC form comes in at roughly 3647.2 g/mol, a difference of about 279 g/mol attributable to the added lysine and maleimidoproprionic acid moiety. That is not a rounding-level difference when converting a mass concentration to a molar one.
A 5 mg vial of the DAC form and a 5 mg vial of the No DAC form do not contain the same number of moles of peptide. Anyone running a protocol defined in molar terms rather than mass terms needs to use the correct molecular weight for whichever variant is on the bench.
Both forms are supplied as the acetate salt and both are soluble in sterile or bacteriostatic water, so reconstitution technique does not differ meaningfully between them. Both are stored lyophilized at -20 C, desiccated, and reconstituted solution is held at 2-8 C for up to thirty days under the catalogue's standard schedule.
The practical handling difference is upstream of reconstitution: because the DAC form is typically used at smaller masses in published protocols, it is stocked at 5 mg rather than the 10 mg format used for the No DAC form. Confirm the vial size matches what the protocol specifies before drawing an aliquot.
The co-lyophilized CJC-1295 + Ipamorelin blend in this catalogue uses the No DAC form specifically, paired 1:1 by mass with Ipamorelin. This is worth noting because the blend is sometimes assumed to use whichever CJC-1295 variant is more commonly discussed, and the two are not the same reagent.
Anyone who needs the DAC variant for an albumin-binding protocol should source it separately rather than assuming a blend product supplies it.
The choice is dictated entirely by whether the protocol depends on serum albumin binding. If it does, the DAC form is the relevant reagent. If it does not - for instance, a straightforward GHRH-receptor binding assay in a defined buffer - the No DAC form is the more commonly stocked and more commonly used variant, and it is the one referenced when CJC-1295 is discussed without qualification.
This guide is general laboratory reference material relating to the handling of research compounds. It is not medical, veterinary or clinical guidance, and it does not describe or imply any use in humans or animals. All PeptideSeed material is supplied for in-vitro laboratory research only — see the terms of supply.