Pal-GHK

What Pal-GHK is, structurally

Pal-GHK is the tripeptide glycyl-histidyl-lysyl carrying a palmitoyl group on its N-terminus. The arithmetic confirms it plainly: the free tripeptide is 340.38, a palmitoyl group adds 238.41, and the sum is 578.79 against the stated 578.80.

That single acyl chain changes the molecule's character completely. Three residues of glycine, histidine and lysine make a small, polar, basic head. A sixteen-carbon saturated chain makes a substantial lipophilic tail. The result is an amphiphile, and amphiphiles do not behave like peptides in solution.

The first consequence is solubility. A tripeptide would be expected to dissolve readily in water; this one may not, because the palmitoyl chain dominates a molecule this small and more than half the molecular weight is lipid. A co-solvent is commonly required, and a vial that resists water is behaving as expected rather than indicating a fault.

The second consequence is that concentration matters in a way it does not for ordinary peptides. Above a threshold, amphiphiles aggregate into micelles rather than remaining as free molecules, so a concentrated stock and a dilute working solution can genuinely differ in what they contain. Behaviour observed at one concentration should not be assumed to carry to another.

One further point follows from the formula rather than the name. The sequence includes histidine, a competent metal ligand, and the parent tripeptide is sold separately here as a copper complex. This material is not that: C30H54N6O5 contains no metal atom, so the chelator precautions a genuine copper complex requires do not apply, and EDTA or citrate in a buffer is not a concern.

There is no sulfur in the formula, so no disulfide chemistry and no oxidation at sulfur.

Reconstitution and handling

Sterile water alone is often insufficient. The conventional approach for a lipopeptide is to dissolve in a small volume of a water-miscible solvent such as DMSO or ethanol, then dilute into aqueous buffer with mixing, rather than taking the solid into water directly.

Add diluent slowly down the inside wall of the vial and swirl gently. Do not vortex; on an amphiphile this generates persistent foam, since the molecule is surface-active by construction.

Adsorptive loss deserves more attention here than on an ordinary peptide. A lipid tail partitions readily onto surfaces, so losses to both plastic and glass can be substantial at low concentration, and low-protein-binding tubes help less than they would with a hydrophilic peptide. Minimising transfers helps more than changing tube.

No reducing agent is needed, since the formula contains no sulfur.

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 warm before opening.

The named chemical liability is the acyl bond. An amide-linked palmitoyl group is reasonably robust, but hydrolysis releases the free tripeptide at 340.38 and palmitic acid, and both extremes of pH accelerate it. Near-neutral conditions are the control, and a loss of 238 units is the signature.

Reconstituted material deserves a shorter working life, not because the chemistry is faster but because the physical state is less stable: amphiphiles can aggregate or come out of solution over time, particularly on cooling.

With no sulfur present, the oxidation routes that dominate many peptides are closed.

These are storage conditions for the material, not dosing or administration guidance.

How Pal-GHK is tested

Reversed-phase HPLC establishes chromatographic purity as area percent, and this molecule sits at the opposite extreme from a short polar peptide. The palmitoyl chain retains strongly on a C18 column, so a gradient built for ordinary peptides may not elute it within the run at all, and a high organic proportion is needed. A late, broad peak is characteristic rather than indicative of a problem.

Detection is best assumed near 214 nm; histidine's imidazole is a weak chromophore, so 280 nm should not be relied on.

Area percent is a chromatographic measure and not peptide content by weight. Solid-phase synthesis delivers a salt, and residual trifluoroacetate is its own impurity class.

Mass spectrometry confirms identity against 578.80. The informative impurity to look for is the free tripeptide at 340.38, which indicates loss of the acyl group, along with any material carrying a shorter or longer acyl chain, each differing by fourteen units per methylene.

These describe general methodology, not a claim about any particular batch.

Handling FAQ

Why will this not dissolve in water like an ordinary tripeptide? Because more than half its molecular weight is a sixteen-carbon lipid chain. The peptide head is small and polar, but the tail dominates a molecule this size, so a water-miscible co-solvent is usually needed before dilution into buffer.

Does this contain copper, like the related GHK complex? No. The formula is C30H54N6O5, which contains no metal atom. The copper complex is a separate product with a different formula and mass, and the chelator precautions it requires do not apply to this material.

Full specifications for Pal-GHK.