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CJC-1295 with DAC vs without DAC
CJC-1295 is sold in two distinct forms that differ by roughly three orders of magnitude in circulating half-life. The difference is a single C-terminal linker: the Drug Affinity Complex (DAC), a maleimidopropionic acid moiety that forms a covalent bond with serum albumin. Choosing between them is a research-design decision about the duration of GHRH-receptor stimulation.
Side-by-side comparison
| Parameter | CJC-1295 with DAC | CJC-1295 without DAC (Mod GRF 1-29) |
|---|---|---|
| Backbone | Tetrasubstituted GHRH(1-29): D-Ala², Gln⁸, Ala¹⁵, Leu²⁷ | Same tetrasubstituted GHRH(1-29) backbone |
| Linker | C-terminal maleimidopropionic acid (DAC) linker on a Lys residue | None |
| Albumin binding | Covalent thioether bond with Cys34 of serum albumin | No covalent albumin binding |
| Reported half-life | ≈6–8 days | ≈30 minutes |
| GH stimulation pattern | Sustained elevation | Discrete pulse |
| Residue count / listed mass | 30 residues including linker; ~3,649.2 Da (catalogue) | 29 residues; ~3,367.1 Da (catalogue) |
| Main research implication | Long exposure window; the stimulus cannot be withdrawn quickly | Exposure ends within hours; suited to pulse-oriented designs |
DAC bioconjugation chemistry: Jetté L. et al., Endocrinology 146(7):3052-3058 (2005), DOI 10.1210/en.2004-1286, and the published DAC platform literature. Half-life ranges: published pharmacokinetic summaries for the two forms. Catalogue masses are as listed on each product page.
How to choose between them
Choose the DAC form when the design needs a sustained stimulus
Because the albumin conjugate circulates for days, it suits protocols where a continuous GHRH-receptor stimulus is the variable under study. Note the corollary: exposure cannot be ended quickly once administered.
Choose the no-DAC form when the design needs a discrete pulse
Mod GRF(1-29) clears within hours, so a stimulation window can be limited to the observation period. It is also the component used in our pre-formulated CJC-1295 + Ipamorelin blend.
Tell them apart analytically before you trust a label
The ~282 Da mass difference between the two forms is the routine check. A vendor quoting a multi-day half-life for a product whose mass matches the linker-free analogue is describing the wrong molecule — a documented point of confusion in this compound class.
Products in this comparison
| Product | List price (per kit of 10 vials) |
|---|---|
| CJC-1295 with DAC | US$159–159 per kit (10 vials), from our published wholesale price list; tiered volume discounts apply (see the tier table) |
| CJC-1295 without DAC | US$85–159 per kit (10 vials), from our published wholesale price list; tiered volume discounts apply (see the tier table) |
| Sermorelin (GHRH 1-29) | US$69–106 per kit (10 vials), from our published wholesale price list; tiered volume discounts apply (see the tier table) |
| Tesamorelin (GHRH 1-44 analogue) | US$111–339 per kit (10 vials), from our published wholesale price list; tiered volume discounts apply (see the tier table) |
| CJC-1295 + Ipamorelin blend | US$103–158 per kit (10 vials), from our published wholesale price list; tiered volume discounts apply (see the tier table) |
FAQ
What exactly is the DAC in CJC-1295?
The Drug Affinity Complex is a maleimidopropionic acid linker attached at the C-terminus. After administration it reacts with the free thiol of Cys34 on serum albumin, forming a covalent thioether bond that converts the peptide into an albumin-bound conjugate (Jetté et al., 2005; DOI 10.1210/en.2004-1286).
Why is the half-life difference so large?
Native GHRH(1-29) is cleared in about 7 minutes, mostly by DPP-IV cleavage at the Tyr¹-Ala² bond. The four backbone substitutions extend that to roughly 30 minutes; covalent albumin binding then protects the peptide from both proteolysis and renal filtration, giving a reported half-life of about 6–8 days.
Is the receptor pharmacology the same for both forms?
Reported binding work indicates yes: the linker sits outside the N-terminal receptor-binding domain, so GHRH-receptor affinity is described as unchanged by the DAC modification. The difference is pharmacokinetic, not receptor-level.
Which form should a first order be?
That depends on your protocol rather than on potency. If you need to compare against published pulse-based GHRH data, the no-DAC form matches that profile; if the study variable is prolonged receptor stimulation, choose the DAC form. Both are on the published price list.
Need a quote for this group?
Component specifications, batch COAs and volume pricing for the whole cluster — quoted within one business day.