CJC-1295 with DAC is a synthetic analog of growth-hormone-releasing hormone based on the biologically active GHRH(1-29) fragment, extended by a drug-affinity complex (DAC) that enables covalent attachment to serum albumin. This addition separates the DAC molecule from other members of the GHRH-analog family and is the reason its circulating profile is measured in days rather than minutes in research models.
The GHRH(1-29) core
The peptide begins with the first twenty-nine residues of human GHRH, the minimal sequence that retains full receptor-activating potency. This truncated backbone is easier to synthesize than the full 44-residue hormone while preserving the pharmacophore that engages the GHRH receptor, the same core underlying its mechanism of action.
Stabilizing substitutions
To resist rapid enzymatic breakdown, the backbone carries deliberate residue substitutions at positions vulnerable to dipeptidyl peptidase and other proteases. These are the same protective modifications found in the no-DAC version, so the two molecules share an armored backbone and differ chiefly in whether the albumin-binding tail is present.
The DAC linker
The defining element is a maleimidopropionic-acid group appended to the peptide. The maleimide is a Michael-acceptor that reacts selectively with a free cysteine thiol on circulating albumin, forming a stable covalent bond. By tethering the peptide to a long-lived carrier protein, the DAC dramatically slows renal clearance and proteolytic degradation, extending the effective research half-life.
Solid-phase assembly
Like most peptides of this length, CJC-1295 with DAC is built by solid-phase peptide synthesis, adding protected amino acids one residue at a time to a growing resin-bound chain. The maleimide-bearing linker is introduced during or after chain assembly, and how ordered sequences translate into function is discussed in understanding amino acid sequences.
Purification and drying
After cleavage from the resin and side-chain deprotection, crude peptide is purified by preparative chromatography and then converted to a stable dry powder by lyophilization (what is lyophilization), which supports shipping and long-term storage of the reactive maleimide group.
Identity and purity confirmation
Analytical HPLC confirms purity while mass spectrometry verifies the expected molecular weight, including the added mass of the DAC linker. Broader context is in the CJC-1295 DAC research overview.
Analytical challenges specific to DAC
The reactive maleimide requires attention during characterization because hydrolysis or unintended thiol reaction changes the chemical species without altering the peptide backbone. Laboratories therefore distinguish intact DAC-bearing material from linker-modified byproducts rather than treating a single purity percentage as complete structural proof. Orthogonal analysis is useful: chromatography resolves major components, mass spectrometry checks molecular identity, and careful sample preparation minimizes reactions introduced during testing. These controls matter because albumin-binding capacity depends on an intact affinity complex, not simply on the presence of the correct twenty-nine-residue sequence.
Product page: CJC-1295 DAC research vials.
Research Use Only. Supplied strictly for laboratory research and development — not for human or veterinary use, consumption, or any therapeutic or diagnostic purpose. This article is research education, not usage guidance.