Peptide glossary
Drug affinity complex (DAC)
Also: DAC · CJC-1295 DAC · albumin binding
A reactive group added to CJC-1295 that bonds it to albumin in blood, stretching a thirty-minute half-life to about a week.
A drug affinity complex is a chemical group, a maleimide attached through a short linker, that reacts with a free cysteine on serum albumin to form a covalent bond. Albumin is the most abundant protein in blood and circulates for weeks, so a peptide bonded to it is protected from enzymatic clearance and kidney filtration and inherits albumin's long residence time. The technology was developed by ConjuChem in the 2000s and CJC-1295 is its best-known application.
The effect on half-life is dramatic. CJC-1295 without DAC, often sold as "Mod GRF 1-29", is a modified GHRH analogue cleared in about thirty minutes, so it produces a short growth-hormone pulse that resembles natural release. With DAC the same peptide persists for roughly six to eight days and raises growth hormone and IGF-1 continuously rather than in pulses. The two versions are therefore studied for different purposes, and the article on CJC-1295 with or without DAC explains the trade-off.
The same principle, extending half-life through albumin binding, underlies the fatty-acid chains on semaglutide and tirzepatide, although those bind albumin reversibly rather than covalently.
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Research & educational use only. Definitions are informational and not medical advice. Products are supplied for laboratory research and are not for human use.