CJC-1295

CJC-1295 (CAS 863288-34-0) is built from the 29-residue N-terminal fragment of human GHRH with four backbone substitutions — D-Ala2, Gln8, Ala15, Leu27 — that block the major protease cleavage sites. A 30th lysine residue at the C-terminus carries a maleimidopropionic acid (MPA) spacer, the so-called Drug Affinity Complex (DAC).

The maleimide reacts selectively with the free thiol on Cys34 of human serum albumin to form a covalent bioconjugate. This albumin tethering is what extends the plasma half-life of CJC-1295 from minutes (bare GHRH(1-29)) to days. Molecular formula: C165H269N47O46; average mass approximately 3647.3 Da.

CJC-1295 is produced by Fmoc solid-phase peptide synthesis followed by selective conjugation of the MPA linker to the C-terminal lysine. The main failure modes:

• Maleimide hydrolysis. The maleimide ring opens to a non-reactive succinamic acid under aqueous storage, especially above pH 7. The hydrolyzed product has nearly the same mass as the intact one (+18 Da) and is the single most common reason a CJC-1295 batch underperforms.
• Incomplete conjugation. A fraction of the material can ship as unmodified Modified GRF(1-29) without the DAC linker — analytically distinct from the intended product but easy to miss without a dedicated functional assay.
• Aspartimide and deamidation. The Asp-Ile and Asn residues in the GHRH backbone are susceptible to aspartimide formation and deamidation under repeated piperidine deprotection.

A well-designed analytical panel resolves these from the main peak. See common peptide impurities for the broader taxonomy.

The standard CertikLabs panel for a CJC-1295 (with DAC) batch:

• RP-HPLC purity (C18, 0.1% TFA / MeCN, UV 214 nm)
• LC-HRMS identity (ESI-Q-TOF, deconvoluted average mass against C165H269N47O46)
• Maleimide functional assay (reaction with a model thiol) to confirm DAC reactivity
• Quantitative HPLC for content
• Size-exclusion HPLC for aggregates and dimer formation

The maleimide functional assay is what separates a real DAC verification from a generic peptide identity check — a hydrolyzed batch will pass mass spec and fail the thiol-reactivity test.

Agonist at the GHRH receptor on pituitary somatotrophs. Stimulates pulsatile growth-hormone release. The DAC linker is the defining feature; without it the analog is conventionally called Modified GRF(1-29) or CJC-1295 without DAC and has a much shorter half-life.

Primary sources:

• Teichman S.L. et al., Prolonged stimulation of growth hormone and IGF-I secretion by CJC-1295, a long-acting analog of GHRH, in healthy adults.(PMID 16352683)
• Jetté L. et al., Human growth hormone-releasing factor (hGRF)1-29-albumin bioconjugates activate the GRF receptor and stimulate GH release.(PMID 15919748)

CertikLabs does not publish dosing, administration routes, or clinical recommendations for CJC-1295.

The maleimide group on the DAC linker is reactive: lyophilized material kept dry, cold, and protected from light is generally stable, but in aqueous solution above pH 7 the maleimide hydrolyzes to a non-reactive succinamic acid and the DAC activity is lost. Re-verification of any working solution is required.