CJC-1295 With DAC vs Without DAC: What's the Difference?
If you have seen two different descriptions of CJC-1295 on UK sites or in papers, you are not imagining it. The name is used for two different molecules, and the difference changes how a study should be read. CJC-1295 without DAC is a 29-amino-acid peptide with four changes from the natural sequence. CJC-1295 with DAC is the same peptide with an extra amino acid and a chemical hook attached. Some papers use the name for both. Our earlier overview of CJC-1295 without DAC covers the basics of the shorter version.
What Is CJC-1295 Without DAC?
CJC-1295 without DAC is also called modified GRF(1-29) or tetrasubstituted GRF(1-29). It starts from the first 29 amino acids of natural GHRH, the part that sermorelin is based on, and changes four of them. Alanine at position 2 becomes D-alanine, asparagine at 8 becomes glutamine, glycine at 15 becomes alanine and methionine at 27 becomes leucine. Both our Modified GRF(1-29) (CJC-1295 no DAC) 10mg and the 2mg CJC-1295 no DAC vial are this version.
Only the first change has been linked to protection from DPP-4, an enzyme that clips the front off the unmodified peptide and leaves an inactive piece. The sources cited here do not give the other three changes a protective role.
What Does the DAC Add?
DAC is short for drug affinity complex. In the DAC version, an extra lysine is added at the end of the chain and a small maleimide group (called MPA) is attached to it. Maleimides react readily with free thiol groups, and the blood protein albumin has one free thiol, at a position called Cys34. That chemistry is well established, which is why DAC is described as an albumin-binding tag.
The molecular formulas back this up. The DAC version weighs about 3,647 daltons, and the difference from the version without DAC works out to one lysine plus the MPA group.
What Did the Original Rat Studies Report?
In a 2005 paper in Endocrinology, Jetté and colleagues made three maleimide versions of GRF(1-29) and attached them to albumin. The conjugates resisted DPP-IV, stimulated growth hormone release from rat pituitary cells and triggered growth hormone release in rats.
CJC-1295 stayed detectable in rat blood for more than 72 hours, and a Western blot linked it to the albumin band. Over two hours it produced a growth hormone response about four times larger than the plain GRF(1-29) peptide. A 2006 study in mice that lack GHRH (Alba and colleagues) then looked at growth after CJC-1295 administration.
Why Does the Difference Matter When Reading Research?
A paper that reports an effect lasting for days is describing the albumin-binding form. Results from the 29-amino-acid modified peptide cannot be read the same way. The methods section should give the sequence or formula, so look for the extra lysine and the MPA group. If a paper only says "CJC-1295", the molecular formula or the supplier's certificate of analysis settles which compound was used. Batch reports like those on our lab reports page are an example of that kind of record. The PubChem record for CJC-1295 lists the DAC formula for comparison.
Important: This article is for scientific information only. The peptides discussed are intended exclusively for scientific and laboratory research and are not intended for human or veterinary consumption, administration, diagnosis, treatment or therapeutic use.