CJC-1295 with DAC

What CJC-1295 with DAC is, structurally

This is a twenty-nine residue peptide carrying an additional chemical group attached at one end, the conjugated form of a peptide this catalogue also sells unconjugated.

Neither the sequence nor the formula is recorded for this product, so the reasoning here rests on the registered formula and on arithmetic between the two forms.

That arithmetic is unusually clean. The unconjugated peptide is C152H252N44O42 at 3367.97; this compound is C165H269N47O46 at 3647.28. Subtracting leaves exactly C13H17N3O4, computing to 279.30 against an observed difference of 279.31. The added group is therefore fully determined by composition even though neither product page states what it is.

Two things follow. It contains no sulfur, and neither does the peptide, so no disulfide chemistry applies to the molecule at all and no reducing agent is ever needed. And three nitrogens and four oxygens across thirteen carbons indicate a small, polar, nitrogen-rich addition rather than a lipid chain or aromatic system: it adds roughly eight percent to the mass without adding hydrophobic bulk.

What the group is for belongs on the research article. Structurally it is an appended moiety at one terminus, with the peptide portion unchanged.

Reconstitution and handling

Sterile water is the default solvent, and with no metal centre present PBS or an appropriate assay buffer are equally suitable. Add diluent slowly down the inside wall of the vial, swirl gently, and let the solution clarify. Do not vortex, since a chain of this length has conformational structure to lose.

No reducing agent should be used. The formula contains no sulfur, so there is nothing for one to act on.

Adsorption onto plasticware is worth allowing for at low concentration, and low-protein-binding tubes reduce measured loss. At around 3647 g/mol this molecule presents appreciably more surface than a short peptide.

This is laboratory preparation chemistry, not dosing, administration, or protocol guidance of any kind.

Storage and stability

Store the lyophilized powder at -20 degrees C, sealed, desiccated and protected from light, and let a cold vial reach room temperature before opening. Reconstituted, hold at 2 to 8 degrees C, or aliquot and freeze rather than thawing repeatedly, and aliquot before the first freeze, since a chain this long can aggregate on cycling.

With no sulfur anywhere in the molecule, the oxidation routes that dominate many peptides are closed: no thiol to oxidise, no methionine to form a sulfoxide, no disulfide to reduce or scramble. Air exposure is correspondingly less important here than for a sulfur-containing peptide of similar size.

The nitrogen count indicates asparagine or glutamine are likely present in the peptide portion, and both deamidate to their acidic counterparts, adding about one mass unit. Without the sequence this page will not name positions.

One liability is specific to a conjugate: the bond attaching the group can hydrolyse, releasing the peptide and leaving two separate species. That shows as a mass loss of 279 rather than a modification of the intact molecule, and it is worth looking for specifically, since a method set up to detect peptide degradation will not necessarily be watching for the conjugate coming apart.

How CJC-1295 with DAC is tested

Reversed-phase HPLC establishes chromatographic purity as area percent. Whether 280 nm is usable depends on aromatic content the formula cannot establish, so the low-UV amide measurement near 214 nm is the reliable channel.

Area percent is a chromatographic measure rather than peptide content by weight. Solid-phase synthesis delivers a salt, associating with the basic sites the nitrogen count indicates.

Mass spectrometry assesses this compound more easily than most, because what it is likeliest to lose has a large unambiguous signature. Loss of the appended group drops the mass 279 units, from 3647 to 3368, far too large to hide in an isotope envelope or be confused with oxidation or deamidation. One spectrum distinguishes conjugate from free peptide outright.

That also means the unconjugated peptide is the impurity class most worth resolving, since it is both the likeliest degradation product and a separate product in its own right. Deletion sequences on a twenty-nine residue chain are the harder case, changing the mass by only a few percent.

Handling FAQ

What is the mass difference between the conjugated and unconjugated forms? 279 units. The conjugate is 3647.28 and the peptide alone is 3367.97, and the appended group accounts for the difference exactly at C13H17N3O4. That gap is large enough to be unambiguous in a mass spectrum.

Does this need protection from reducing agents, as some conjugates do? No. The formula contains no sulfur at all, so there is no disulfide linkage and nothing for a reducing agent to cleave. The attachment is not thiol-based in the supplied molecule.

Full specifications for CJC-1295 with DAC.