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Glossary

DAC (Drug Affinity Complex)

The Drug Affinity Complex links a peptide covalently to circulating albumin so its half-life moves from minutes to days. Consequences for experimental design.

The Drug Affinity Complex (DAC) is a maleimidoproprionic acid moiety attached at a peptide’s carboxy terminus. Once in the bloodstream, this group couples to the free thiol of cysteine-34 on serum albumin, forming a stable thioether link, so the small molecule travels piggyback on albumin, a protein of 66 kDa. Instead of being filtered out by the kidney, albumin is recycled via the neonatal Fc receptor, so the attached peptide takes on albumin’s long residence time.

Implications for study design

Best known is CJC-1295 with DAC, a GHRH (1-29) analog carrying four substitutions. Published human pharmacokinetic data gave the DAC construct a terminal half-life counted in days, whereas unmodified GHRH fragments — CJC-1295 without DAC, for instance — last only minutes. For an experimental design this is a fundamental difference, not a detail: material with DAC yields a prolonged rise in the measured signal, whereas material without it yields separate pulses. Animal or clinical results from one construct cannot stand in for the other, and conclusions for one must not be transferred to the other.

DAC alters handling assumptions as well. The modification withstands lyophilisation but depends on the maleimide staying intact, so hydrolysed or heat-damaged material may lose albumin binding while a mass check still identifies it as the parent peptide. For context, read our CJC-1295 with DAC overview next to the broader guide on stability and half-life.

See also stability and PEGylation, or browse the collection of GHRH analogs

Related catalog items

CJC-1295 (No DAC / Mod GRF 1-29)

All glossary terms

Further reading

Guides that reference this term

Comparisons

CJC-1295 With and Without DAC: Albumin Conjugation and Exposure Pattern in Research

A single extra lysine carrying a maleimide stretches a GHRH analogue's persistence from minutes to days. Here is what that means at the receptor, on the bench and on the COA.

Molecule guides

What Is CJC-1295 with DAC? Albumin Conjugation, GHRH Receptor Pharmacology and Research Use

The long-acting GHRH analogue explained: how its maleimide linker latches onto albumin Cys34, what days-long receptor occupancy changes, and how to handle and verify the material.

Molecule guides

CJC-1295 + Ipamorelin: Two Receptors, One Somatotroph, and the Arithmetic of a Blend

A co-lyophilized GHRH analogue and selective ghrelin-receptor agonist: the pathway logic, the fixed molar ratio it locks in, and how to read its COA.

Molecule guides

Peptide Half-Life and Stability: What DAC, PEG, Acetylation and Aib Actually Do

Shelf life and circulating half-life are different problems with different fixes. The clearance routes, the chemistry that blocks each one, and how to do the maths.