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Research use only
· 8 min read
The name CJC-1295 appears on two different molecules. That is not a rounding error or a supplier shorthand - it is a documented source of cross-catalogue confusion that shows up in the analytical literature every time a researcher cross-references a database. Both are GHRH-receptor agonists sharing the same 29-residue backbone and the same four protective substitutions. The difference between them is a single C-terminal lysine carrying a maleimido-propionyl linker - present on the with-DAC form, absent on the no-DAC form - and that difference produces two distinct molecular formulae, two distinct PubChem records, and behaviour in biological matrices that is nothing alike. Everything below describes what published studies have investigated, grouped strictly by GHRH-receptor pharmacology, not any human use. Kovalabs supplies CJC-1295 with DAC and CJC-1295 without DAC strictly as research reagents for laboratory and in-vitro research only.
| Compounds | CJC-1295 with DAC (drug affinity complex) and CJC-1295 without DAC (modified GRF 1-29) |
|---|---|
| Synonyms / dev codes | With-DAC: CJC-1295, CJC-1295 DAC. No-DAC: CJC-1295 no DAC, modified GRF 1-29, mod-GRF 1-29 |
| Class / mechanism | Synthetic GHRH(1-29) / GRF(1-29) analogues; agonists at the GHRH receptor (GHRH-R), a class B1 GPCR on pituitary somatotrophs |
| Molecular formula (DAC) | C165H269N47O46 |
| Molecular weight (DAC) | Approximately 3647.2 g/mol |
| Molecular formula (no-DAC) | C152H252N44O42 |
| Molecular weight (no-DAC) | Approximately 3367.9 g/mol |
| PubChem CID | With-DAC: 91971820. No-DAC: 91976842 (related stereo-resolved record 56841945) |
| CAS number | No-DAC commonly 446036-97-1; with-DAC commonly 863288-34-0 or 446262-90-4 (CAS contested across sources, moderate confidence; use molecular formula as the authoritative discriminator) |
Both forms are built on the GHRH(1-29) / GRF(1-29) sequence - the same 29-residue active fragment that underlies sermorelin - and both carry four amino-acid substitutions: D-Ala at position 2, Gln at position 8, Ala at position 15 and Leu at position 27. Those substitutions cluster at and around the dipeptidyl-peptidase-IV (DPP-IV) cleavage site at the N-terminus, where DPP-IV otherwise clips the native Tyr1-Ala2 bond of GHRH(1-29). Substituting position 2 is the documented structure-activity strategy used across GRF analogues to reduce that cleavage, and it is shared by both forms.
The structural fork happens at the C-terminus. The with-DAC form adds a Lys30 whose epsilon-amino group is acylated with a 3-(maleimido)propionyl group - published as the N-epsilon30-maleimidopropionyl extension of the modified sermorelin sequence. The no-DAC form (modified GRF 1-29) carries nothing there. Because the bare label CJC-1295 is used for both forms in the literature, identity should be confirmed by molecular formula and mass, not by name. PubChem CID 91971820 resolves to C165H269N47O46 at approximately 3647.2 g/mol, with the 2,5-dioxopyrrol-1-yl (maleimido) group visible on a C-terminal lysine side chain in the connectivity record. PubChem CID 91976842 resolves to C152H252N44O42 at approximately 3367.9 g/mol, with a related stereo-resolved record at CID 56841945. The difference between the two formulae is exactly +C13H17N3O4 - the composition of one maleimido-propionyl lysine.
CAS is a separate headache. The no-DAC form is most consistently listed as 446036-97-1, while the with-DAC form appears as 863288-34-0 or 446262-90-4 depending on the registry, and at least one database mis-pairs a CAS with the wrong formula. CAS is therefore reported at moderate confidence only; the molecular formula - C165 for DAC versus C152 for no-DAC - is the authoritative discriminator.
| Property | CJC-1295 with DAC | CJC-1295 without DAC |
|---|---|---|
| Common names | CJC-1295, CJC-1295 DAC | Modified GRF 1-29, mod-GRF 1-29, CJC-1295 no DAC |
| Defining structural feature | Adds a C-terminal Lys30 acylated with a 3-(maleimido)propionyl linker | Lacks the maleimido-lysine extension |
| Molecular formula | C165H269N47O46 | C152H252N44O42 |
| Molecular weight | Approximately 3647.2 g/mol | Approximately 3367.9 g/mol |
| PubChem CID | 91971820 | 91976842 (related 56841945) |
| CAS number (contested, moderate confidence) | 863288-34-0 or 446262-90-4 | 446036-97-1 |
| Receptor target | GHRH receptor (GHRH-R) | GHRH receptor (GHRH-R) |
| Backbone substitutions | D-Ala2, Gln8, Ala15, Leu27 | D-Ala2, Gln8, Ala15, Leu27 |
| Behaviour in biological matrices | Covalently bioconjugates to serum-albumin Cys34; behaves as a high-molecular-weight albumin conjugate | Discrete approximately 3.4 kDa peptide, no albumin anchor |
The with-DAC design is, at its core, a bioconjugation strategy. The foundational paper is Jette et al. (Endocrinology, 2005; PMID 15817669; DOI 10.1210/en.2004-1286), which synthesised three maleimido derivatives of human GHRH(1-29), bioconjugated them ex vivo to human serum albumin, and assessed them across an in-vitro DPP-IV stability assay, a growth-hormone secretion assay in cultured rat anterior-pituitary cells, and subcutaneous administration to Sprague-Dawley rats. That paper identified CJC-1295 as the long-acting analogue and is the structural source of the maleimido-lysine albumin-bioconjugation mechanism. Its endpoint names include a disease-relevant secretion endpoint; this study is cited here for its design and the mechanism it characterised only - no result, effect size, direction or benefit is asserted.
The chemistry is a thiol-Michael addition. The maleimide on the C-terminal Lys30 of the with-DAC form reacts spontaneously and selectively with the free thiol of Cys34 on circulating serum albumin, forming a stable thioether covalent bond. The resulting peptide-albumin conjugate is large enough to escape rapid renal filtration and is sterically shielded from proteolysis - which is the documented structural basis for the with-DAC form presenting as a high-molecular-weight albumin conjugate in biological matrices rather than a discrete peptide. The no-DAC form carries no such reactive group. Both share the DPP-IV-resistant backbone substitutions, so the comparison is entirely about the presence or absence of the albumin anchor, not about receptor identity.
The CJC-1295 literature treats the two forms as distinct chemical species throughout. The entries below are described strictly by what each study set out to measure; no result, effect size or therapeutic benefit is asserted or implied.
Both forms are supplied as lyophilised (freeze-dried) powder for laboratory reconstitution. As peptides, reconstitution means directing the diluent against the vial wall and swirling gently rather than vortexing - mechanical shear and foaming can denature peptide chains, and this is bench handling of a reagent, not a preparation for any use. The general procedure is on the reconstitution guide and is not repeated here.
For storage, lyophilised peptide is held desiccated and cold: longer-term at -20 C or colder for the freeze-dried solid, short-term at 2 to 8 C. A reconstituted solution is kept refrigerated, protected from light, with freeze-thaw cycling minimised. The analytical literature on GHRH analogues is direct on this point: Coppieters et al. (2022) documented accelerated degradation of related GHRH peptides above 4 C and at low pH, which is the published basis for the cold-chain handling requirements that protect research integrity.
The two forms also diverge analytically, and that divergence matters for method selection. Because the with-DAC form covalently conjugates to albumin Cys34, it resists top-down mass-spectrometric peptide screening in biological matrices and requires immuno-affinity capture or tryptic digestion to detect - presenting as an undefined-mass macromolecule rather than a discrete analyte. The no-DAC form is handled as a discrete peptide of roughly 3.4 kDa. Peptide identity and purity are verifiable rather than assumed: every Kovalabs batch ships with a certificate of analysis, so the mass and purity of the material in hand can be checked against the documented identifiers (C165H269N47O46 for the DAC form, C152H252N44O42 for the no-DAC form) rather than taken on trust. Related GHRH-receptor and GH-axis compounds are grouped under GH-axis research peptides.
CJC-1295 with DAC and CJC-1295 without DAC are supplied by Kovalabs for laboratory and in-vitro research only. They are not medicines, not supplements, and not for human or veterinary use, and nothing on this page describes a dose, a route, a schedule or an outcome. They are research compounds that have not been evaluated by the MHRA or any comparable regulator for safety or efficacy in humans or animals. Every batch is third-party tested with a certificate of analysis. See the full research disclaimer for terms.
A single structural feature. The with-DAC form carries an extra C-terminal lysine (Lys30) acylated with a 3-(maleimido)propionyl group, the drug affinity complex; the no-DAC form (modified GRF 1-29) lacks it. Both share the same GHRH(1-29) backbone and the same four substitutions (D-Ala2, Gln8, Ala15, Leu27), so they target the same GHRH receptor. The difference shows up in the molecular formula: C165H269N47O46 for the DAC form against C152H252N44O42 for the no-DAC form.
It is bioconjugation chemistry. The maleimide on the C-terminal lysine of the with-DAC form reacts selectively with the free thiol of Cys34 on serum albumin to form a stable thioether bond. The published literature (Jette et al., Endocrinology, 2005) characterises this albumin conjugation as the structural basis for the with-DAC form persisting as an albumin conjugate in biological matrices. The no-DAC form has no such reactive group.
By molecular formula or mass, not by name. The label CJC-1295 is used for both forms in the literature, which is the documented source of confusion. The with-DAC form is C165H269N47O46 (approximately 3647.2 g/mol, PubChem CID 91971820); the no-DAC form is C152H252N44O42 (approximately 3367.9 g/mol, PubChem CID 91976842). A certificate of analysis lets you check the mass of the material in hand against these identifiers.
Registry and vendor sources genuinely disagree on CAS assignment for these molecules. The no-DAC form is most consistently listed as 446036-97-1, while the with-DAC form appears as 863288-34-0 or 446262-90-4 depending on the source, and at least one database mis-pairs a CAS with the wrong formula. Because of this, CAS is reported at moderate confidence only, and the molecular formula (C165 versus C152) is treated as the authoritative discriminator.
As bench handling of a research reagent only. Lyophilised peptide is kept desiccated and cold, with longer-term storage at -20 C or colder and short-term holding at 2 to 8 C; a reconstituted solution is refrigerated, protected from light, and freeze-thaw cycling is minimised. Reconstitution is a gentle dissolution step (diluent against the vial wall, swirl rather than vortex). None of this is a preparation method for any use in humans or animals; see the reconstitution guide for general handling.
No. Neither CJC-1295 with DAC nor CJC-1295 without DAC has been approved as a medicine by the MHRA or any comparable regulator. Kovalabs supplies both strictly as research reagents for laboratory and in-vitro use, not for human or veterinary use. Both forms are listed on the World Anti-Doping Agency Prohibited List, which is the reason the bioanalytical detection literature on them exists.