Guide

GHK-Cu vs GHK basic

The same three amino acids, with and without the copper ion. What the copper adds to the mass, the colour and the chemistry.

Published September 4, 2026

Three amino acids, glycine, histidine and lysine. One version carries a copper ion and one does not.

Peptide	Vial sizes	From
GHK-Cu	50mg	$24.99 CAD
GHK Basic	Single size	$56.99 CAD
KPV + GHK-Cu Blend	10mg + 50mg	$53.99 CAD

Free shipping across Canada. Every vial ships with a QR code linking to its own batch lab report. See all peptides

The tripeptide and the complex

GHK is a tripeptide that occurs naturally in human plasma. Its sequence is three residues long, which makes it one of the smallest molecules in the catalog at 340.38 g/mol.

The histidine in the middle is a copper-binding residue. GHK-Cu is that tripeptide with a copper(II) ion held in the complex, which brings the mass to 403.91 g/mol and turns the solution blue.

Most published research on this molecule is on the copper complex rather than the free peptide, and the copper is understood to be part of what is being studied rather than a delivery detail.

The numbers

	Sequence	Formula	Molecular weight	CAS
GHK basic	GHK	C14H24N6O4	340.38 g/mol	72957-37-0
GHK-Cu	GHK, copper complex	C14H22CuN6O4	403.91 g/mol	49557-75-7

The copper form has two fewer hydrogens because the copper displaces them when it binds. That, plus the copper's own 63.5 g/mol, gives the 63.53 difference.

Colour is a free check

This is one product where you can see something about identity without a lab. A reconstituted GHK-Cu solution is blue, because copper(II) complexes absorb red light. GHK basic reconstitutes colourless.

That is not a purity test and it does not replace a report. But a vial labelled GHK-Cu that dissolves to a clear colourless solution is a vial to check against its report before using it. Look up the batch and read the mass-spec line.

Molar concentration is unusually high

These are tiny molecules, so a vial holds a lot of them. Our GHK-Cu vial is 50 mg, which is about 124 micromoles. A 50 mg vial of a 5,000 g/mol peptide would be about 10.

Vial	1 mL	2 mL	3 mL	5 mL
50 mg	50 mg/mL124 mM	25 mg/mL61.9 mM	16.7 mg/mL41.3 mM	10 mg/mL24.8 mM

GHK-Cu vial sizes we sell, at four diluent volumes. Molarity uses 403.91 g/mol. Other volumes

In the blends

Three of our blends carry the copper form: GLOW, KLOW and the KPV + GHK-Cu blend. The mass on a blend label is the combined content, and the report states the ratio for that batch. Peptide blends explained covers what that means for the numbers.

Bottom line

340 g/mol is the bare tripeptide. 404 is the copper complex. The complex is blue and the peptide is not.

For research use only. Not for human or animal consumption.

Frequently asked questions

What is the difference between GHK-Cu and GHK?+

One copper ion. GHK is the tripeptide glycyl-histidyl-lysine at 340.38 g/mol. GHK-Cu is the same tripeptide complexed with copper(II) at 403.91. The 63.5 g/mol difference is the copper.

Why is GHK-Cu blue?+

Copper(II) complexes absorb in the red part of the spectrum, so the solution looks blue. A GHK-Cu vial that reconstitutes colourless is a reason to check the report, because the copper is what gives the complex its colour.

Which one appears in the blends?+

The copper form. Both the GLOW and KLOW blends and the KPV blend use GHK-Cu, and the vial's lab report states the ratio for that batch.

Does GHK basic need different handling?+

No. Both are small, stable tripeptides that reconstitute the same way. Copper complexes are light-sensitive, so keep a reconstituted GHK-Cu vial out of direct light.

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