CJC-1295 No DAC Explained: Understanding Its Molecular Structure

In the landscape of synthetic GHRH analogs, few compounds have generated as much discussion or as much confusion as CJC-1295 No DAC. Part of the confusion comes from naming. CJC-1295 No DAC and CJC-1295 with DAC are related but structurally distinct compounds with meaningfully different pharmacokinetic profiles. The No DAC variant is also known as Modified GRF 1-29, or Mod GRF 1-29, and understanding why these names exist and what they describe is the first step toward understanding the compound itself.

This article focuses specifically on CJC-1295 No DAC, its molecular architecture, the structural modifications that distinguish it from both native GHRH and the DAC-containing variant, and what researchers need to understand before working with this compound in laboratory settings.

For researchers sourcing this compound, the structural specificity of the molecule makes analytical verification particularly important. Oasis Peptides provides research-related compound information that researchers can review when evaluating product identity, mass spectrometry confirmation, and HPLC purity documentation.

The Foundation: Native GHRH and Its Limitations

To understand what CJC-1295 No DAC is, you need to understand what it was designed to improve upon. Native growth hormone-releasing hormone, GHRH, is a 44-amino-acid peptide produced in the hypothalamus. It travels through the portal circulation to the anterior pituitary gland, where it binds to the GHRH receptor on somatotroph cells and stimulates the synthesis and pulsatile release of growth hormone.

The biological activity of GHRH resides primarily in its first 29 amino acids. The carboxyl-terminal portion of the molecule from residue 30 onward contributes to binding but is not essential for receptor activation. This discovery led researchers to investigate shorter fragments of GHRH, with the 1-29 fragment, GHRH(1-29), becoming the primary focus of analog development work.

Native GHRH, and the shorter GHRH(1-29) fragment, share a significant limitation: rapid degradation in circulation. The enzyme dipeptidyl peptidase-4, DPP-4, cleaves at a specific position near the amino terminus of the peptide, and additional plasma peptidases contribute to degradation elsewhere in the sequence. The result is a very short half-life, measured in minutes, that limits the utility of the native sequence for sustained receptor engagement in research contexts.

The Four Modifications That Define Mod GRF 1-29

CJC-1295 No DAC, also called Modified GRF 1-29, is a 29-amino-acid synthetic analog of GHRH(1-29) that incorporates four specific amino acid substitutions designed to address the metabolic stability problem. Each substitution targets a different vulnerability in the native sequence.

Position 2: DPP-4 Protection

The first and most critically important modification is at position 2 in the sequence. In native GHRH(1-29), position 2 is occupied by alanine. In Mod GRF 1-29, alanine at position 2 is replaced with D-alanine, the mirror-image stereoisomer of the natural L-alanine.

DPP-4 cleaves peptides at the bond between positions 1 and 2 when position 2 is a natural L-amino acid. The D-alanine substitution at position 2 is not recognized efficiently by DPP-4, providing substantial protection against this primary degradation pathway. This single modification is responsible for much of the improved metabolic stability of Mod GRF 1-29 compared to the native sequence.

Position 8: Oxidation Resistance

Position 8 in native GHRH(1-29) contains a methionine residue. Methionine is susceptible to oxidation, particularly the sulfur atom in its side chain, which can be converted to methionine sulfoxide under oxidizing conditions. This oxidation alters the local structure of the peptide and can affect both receptor binding and metabolic stability.

In Mod GRF 1-29, the methionine at position 8 is replaced with leucine. Leucine is chemically similar in size and hydrophobicity to methionine but lacks the oxidation-sensitive sulfur group, providing protection against oxidative degradation without substantially disrupting the structural features that support receptor binding at this region of the molecule.

Position 15: Stability Enhancement

Position 15 is occupied by glutamine in native GHRH(1-29). Glutamine residues in peptides are susceptible to deamidation, a chemical reaction where the amide group in the side chain is hydrolyzed to a carboxylate, converting glutamine to glutamate. Deamidation changes the charge and character of the residue and can affect both the secondary structure of the peptide and its interaction with receptors.

The substitution at position 15 in Mod GRF 1-29 replaces glutamine with alanine, a small non-reactive amino acid that is not susceptible to deamidation. This modification improves chemical stability under storage conditions and in biological matrices.

Position 27: Binding Affinity Enhancement

The fourth modification in Mod GRF 1-29 is at position 27, where leucine in the native sequence is replaced with arginine. Unlike the first three modifications which are primarily stability-oriented, this substitution was incorporated to improve receptor binding affinity.

Arginine has a positively charged guanidinium group in its side chain that can form favorable ionic interactions and hydrogen bonds with complementary features in the GHRH receptor binding pocket. Replacing the hydrophobic leucine at this position with the charged arginine enhances receptor engagement in a way that partially compensates for any binding reduction that might otherwise result from the stability-oriented modifications at other positions.

The Resulting Pharmacokinetic Profile

These four modifications collectively produce a compound with a significantly extended half-life compared to native GHRH(1-29), while retaining the receptor binding and activation properties of the native sequence. Published research on Mod GRF 1-29 describes a half-life in the range of 20 to 30 minutes in vivo, compared to the few minutes characteristic of unmodified GHRH analogs.

This extended but not indefinite half-life is the defining pharmacokinetic feature of CJC-1295 No DAC. It provides a meaningful window for experimental work requiring sustained GHRH receptor engagement while maintaining a profile consistent with physiological pulsatile signaling patterns, because the compound is cleared between pulses rather than accumulating over extended periods.

This is the critical distinction from CJC-1295 with DAC, which incorporates a drug affinity complex that binds albumin and extends the half-life dramatically to days rather than minutes or hours.

For researchers evaluating which GHRH analog best suits their experimental design, the pharmacokinetic differences between these variants are fundamental. Researchers can consult Oasis Peptides for compound-specific information and available analytical documentation to better understand the importance of verifying structural identity before laboratory research.

GHRH Receptor Binding and Signal Transduction

CJC-1295 No DAC acts through the GHRH receptor, a class B G-protein coupled receptor expressed on pituitary somatotroph cells. The four-modification structure of Mod GRF 1-29 was designed to preserve the receptor binding and activation characteristics of the native GHRH(1-29) sequence while improving stability and resistance to degradation.

The GHRH receptor signals primarily through Gs proteins, activating adenylyl cyclase and increasing intracellular cyclic AMP levels. Elevated cyclic AMP in somatotrophs activates downstream kinases that ultimately drive growth hormone gene expression and trigger growth hormone release through exocytosis of secretory granules.

Receptor activation by Mod GRF 1-29 follows the two-step binding mechanism characteristic of class B GPCRs. The carboxyl-terminal region of the 29-amino-acid sequence engages the extracellular domain of the receptor, positioning the amino-terminal region for interaction with the transmembrane bundle that triggers receptor activation. The D-alanine at position 2 protects the amino terminus from DPP-4 cleavage while preserving its ability to participate in this activation step.

Analytical Verification Requirements

The structural specificity of CJC-1295 No DAC, particularly the four non-natural or substituted amino acid positions, makes thorough analytical verification particularly important for research procurement.

Mass spectrometry confirmation should verify a molecular weight consistent with the full Mod GRF 1-29 sequence including all four modifications. The theoretical molecular weight of Mod GRF 1-29 is well established, and a measured molecular weight matching this value is strong evidence of structural integrity. Any significant deviation from the expected molecular weight, particularly a value corresponding to unmodified GHRH(1-29) or to a partially modified sequence, indicates a quality problem that should preclude use of the material.

HPLC purity analysis should demonstrate a predominant peak corresponding to the intact Mod GRF 1-29 molecule, with impurity peaks characterized sufficiently to rule out the presence of structurally related compounds at levels that could affect experimental conclusions. Research-grade material should meet purity thresholds of 98 percent or higher for applications where compound integrity is critical.

Experimental Design Considerations

Researchers incorporating CJC-1295 No DAC into experimental protocols need to account for several factors that arise from its specific properties.

The half-life of 20 to 30 minutes means that single-dose studies will capture an acute growth hormone response that returns toward baseline as the compound is cleared. Studies investigating sustained effects will require repeated dosing at intervals appropriate to the compound’s clearance rate.

The pulsatile context of growth hormone secretion should be incorporated into experimental design. Background somatostatin tone, the counter-regulatory hormone that inhibits growth hormone release, varies in normal physiology and can affect the magnitude of the growth hormone response to GHRH receptor stimulation. Controlling for or measuring somatostatin tone alongside growth hormone responses provides more complete mechanistic data.

IGF-1 measurement as a downstream readout of cumulative growth hormone secretion complements direct growth hormone quantification and provides a more stable, time-integrated measure of axis activation.

Final Thoughts

CJC-1295 No DAC is a structurally specific synthetic GHRH analog whose four amino acid modifications address the primary limitations of the native GHRH(1-29) sequence for research applications. Understanding the rationale behind each modification, the pharmacokinetic profile that results, and the analytical verification requirements appropriate for this compound gives researchers the foundation needed to work with it effectively and interpret results with confidence.

In growth hormone axis research, structural precision matters at every level. Starting with a well-characterized compound and designing experiments that account for its specific properties is how meaningful science gets done.

Disclaimer: CJC-1295 No DAC and all related peptide compounds referenced in this article are intended strictly for laboratory and scientific research purposes only. These products are not approved for human consumption, self-administration, or any application outside of formally regulated research environments. This content is purely educational in nature and does not constitute medical advice, treatment recommendations, or endorsement of any specific use. All researchers must ensure full compliance with applicable institutional guidelines, regional regulations, and national laws when procuring, storing, and handling research compounds.