CJC-1295 with and without DAC: what the names mean
“CJC-1295” is one of the most confusing names in peptide research. It is used for two different molecules: one with a chemical extension called DAC and one without. This guide explains the chemistry behind both names and how to tell which molecule is in a vial.
The starting point: GRF(1-29)
Growth hormone-releasing factor (GRF, also called GHRH) is a 44-residue hypothalamic peptide. Its first 29 residues, GRF(1-29), retain binding to the GRF receptor and are known as sermorelin. Native GRF(1-29) is quickly cleaved in plasma, notably by dipeptidyl peptidase-4 between residues 2 and 3.
Four substitutions: modified GRF(1-29)
The peptide sold as “CJC-1295 without DAC” is GRF(1-29) with four amino acid substitutions:
- D-Ala2 in place of L-Ala, to resist cleavage at the N-terminus
- Gln8 in place of Asn, to reduce deamidation
- Ala15 in place of Gly
- Leu27 in place of Met, removing an oxidation-prone methionine
This tetrasubstituted peptide is often called Mod GRF(1-29). Its sequence is Tyr-D-Ala-Asp-Ala-Ile-Phe-Thr-Gln-Ser-Tyr-Arg-Lys-Val-Leu-Ala-Gln-Leu-Ser-Ala-Arg-Lys-Leu-Leu-Gln-Asp-Ile-Leu-Ser-Arg-NH2, with formula C152H252N44O42 and an average mass of about 3367.9 g/mol.
What DAC means
DAC stands for drug affinity complex, an albumin-binding conjugation strategy. In CJC-1295 the same modified GRF(1-29) is extended by a lysine at position 30 whose side chain carries a maleimidopropionyl group. The maleimide is designed to react with the free thiol of cysteine 34 on serum albumin, forming a covalent bioconjugate. The work was described in rats by Jetté and colleagues (Endocrinology, 2005), whose paper identified CJC-1295 as the lead compound among a series of GRF(1-29)-albumin bioconjugates.
CJC-1295 with DAC has the formula C165H269N47O46 and an average mass of about 3647.3 g/mol.
Side by side
| CJC-1295 without DAC | CJC-1295 with DAC | |
|---|---|---|
| Also called | Mod GRF(1-29), tetrasubstituted GRF(1-29) | CJC-1295 (original name) |
| Length | 29 residues, C-terminal amide | 30 residues (Lys30 with maleimidopropionyl group) |
| Formula | C152H252N44O42 | C165H269N47O46 |
| Average MW | ≈ 3367.9 g/mol | ≈ 3647.3 g/mol |
| Albumin-binding group | None | Maleimide |
Why the names get mixed up
In the original literature, “CJC-1295” meant the DAC molecule. Over time, suppliers began labeling Mod GRF(1-29) as “CJC-1295 no DAC”, and the bare name now appears for both. When reading a paper or a label, look for the sequence, the presence of Lys30 and the stated mass rather than the name alone.
Telling them apart by mass spectrometry
The two forms differ by about 279 g/mol, which is easy to resolve. Peptides of this size appear in electrospray spectra mainly as multiply charged ions. For Mod GRF(1-29), expect the [M+3H]3+ ion near m/z 1123.6 and [M+4H]4+ near m/z 843.0; the DAC form shifts these to roughly 1216.8 and 912.8. See reading a mass spectrum on a peptide COA.
Ipamorelin: a separate molecule
CJC-1295 without DAC is often supplied in a blend with ipamorelin, which acts at a different receptor. Ipamorelin is a synthetic pentapeptide agonist of the growth hormone secretagogue receptor (GHS-R1a, the ghrelin receptor), with the sequence Aib-His-D-2-Nal-D-Phe-Lys-NH2, formula C38H49N9O5 and an average mass of about 711.9 g/mol. It was first characterized in pituitary cell assays and in rat and swine models by Raun and colleagues (Eur J Endocrinol, 1998). It shares no sequence with GRF.
In a two-component lot, HPLC should show two separate main peaks and the mass panel should confirm both masses. See how mass spectrometry confirms identity.
All LA Peptides products are supplied for laboratory research use only and are not for human or veterinary use.
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All LA Peptides products are sold for laboratory research only. Not for human or veterinary use.
View CJC No DAC / Ipamorelin and its per-lot certificate of analysis
For laboratory research use only. Not for human or veterinary use. This guide summarizes published scientific literature for context. It is not medical advice and does not describe any product as suitable for human use.