AHK-Cu (Copper Peptide)

AHK-Cu is the tripeptide L-alanyl-L-histidyl-L-lysine bound to a copper(II) ion. It is a close structural relative of GHK-Cu, the naturally occurring plasma copper peptide glycyl-L-histidyl-L-lysine-Cu2+, from which it differs only by an alanine in place of the N-terminal glycine. In both peptides the copper is held by the N-terminal amine, the histidine imidazole nitrogen and backbone amide nitrogens, a chelation motif whose thermodynamics have been characterised by isothermal titration calorimetry for GHK and the albumin N-terminal analogue DAHK [5]. AHK-Cu appears in the cosmetic-ingredient literature and in hair-care formulations; its published research record is small and almost entirely in vitro.

The GHK-Cu background

Most of what is claimed for copper peptides was established for GHK-Cu, not AHK-Cu, and the distinction matters. Maquart et al. (1988) reported that GHK-Cu stimulated collagen synthesis in cultured fibroblasts at nanomolar to micromolar concentrations, with the copper complex more active than either component alone [3]. Pickart and Margolina's 2018 review collates the subsequent GHK-Cu literature: wound-healing models, fibroblast and keratinocyte studies, and gene-expression profiling in which GHK reset the expression of large numbers of genes, alongside a substantial cosmetic-trial record for topical GHK-Cu formulations [4]. AHK-Cu is often marketed on the strength of these data by analogy. The analogy is chemically reasonable — the copper-binding core is identical — but the two peptides have not been compared head-to-head in most assays, and the research record for AHK-Cu itself is what follows.

The AHK-Cu evidence: hair follicle organ culture

The principal study is Pyo et al. (2007), published in Archives of Pharmacal Research. The group cultured human hair follicles ex vivo and human dermal papilla cells (the specialised fibroblasts at the follicle base that instruct hair growth) in vitro, and exposed them to AHK-Cu at 10−12 to 10−9 M. AHK-Cu stimulated elongation of the follicles in organ culture and proliferation of the dermal papilla cells. At 10−9 M it reduced the fraction of apoptotic dermal papilla cells (a trend that did not reach statistical significance), raised the Bcl-2/Bax ratio, and lowered levels of cleaved caspase-3 and cleaved PARP. The authors proposed that AHK-Cu promotes follicle growth by stimulating dermal papilla proliferation and restraining apoptosis [1]. The same group had earlier noted that the tripeptide-copper complex increases dermal-fibroblast proliferation and vascular endothelial growth factor production while decreasing TGF-β1 secretion, which is the rationale for examining it in follicle biology.

Copper peptides and hair growth in animal models

The idea that copper-binding peptides can enlarge hair follicles predates AHK-Cu. Uno and Kurata (1993), reviewing agents tested on the macaque model of androgenetic alopecia, reported that a copper-binding peptide (PC1031) applied to the back skin of fuzzy rats enlarged vellus follicles, an effect they compared to topical minoxidil, as measured by folliculogram and follicular DNA synthesis [2]. That work concerns a different copper peptide and a rodent model, and is cited here for the mechanistic lineage rather than as evidence for AHK-Cu specifically.

How AHK-Cu is examined in the laboratory

• Dermal papilla cell assays — proliferation, apoptosis markers (Bcl-2/Bax, caspase-3, PARP) and growth-factor secretion in cultured human dermal papilla cells [1].
• Hair follicle organ culture — shaft elongation of isolated human follicles over days in culture [1].
• Comparative copper-peptide work — collagen synthesis, fibroblast responses and gene-expression readouts benchmarked against GHK-Cu [3][4].
• Copper coordination chemistry — binding affinity and redox behaviour of the His-Lys copper site [5].

What the research does not establish

The AHK-Cu literature indexed in PubMed consists essentially of a single in-vitro and ex-vivo paper [1]. There are no controlled human trials of AHK-Cu for hair growth, skin ageing or wound healing, and the clinical-style claims attached to it in the marketplace are borrowed from GHK-Cu, a different molecule with its own data [3][4]. Follicle elongation in organ culture over days does not predict hair regrowth in a person, and the animal copper-peptide data [2] concern another compound. Nothing establishes how AHK-Cu behaves systemically. This material is supplied strictly for in-vitro laboratory research.

Format. Lyophilized blue-to-violet powder in a sealed glass vial; the colour comes from the copper(II) complex. Stated mass refers to the peptide-copper complex.

Reconstitution. Reconstitute with sterile or bacteriostatic water, directing the stream against the glass wall and swirling gently until dissolved. Copper peptides are best kept in neutral to slightly acidic solution; strongly acidic or chelating buffers (EDTA, citrate, phosphate at high concentration) will strip the copper and change the compound. Our reconstitution calculator converts vial mass and diluent volume into concentration.

Storage. Lyophilized vials are typically stored at −20 °C and protected from light. Reconstituted solutions are generally refrigerated at 2–8 °C and used within days; copper(II) can catalyse oxidation of other components in a mixed formulation, so combine with reducing agents (ascorbate, thiols) only immediately before use.

Handling. Standard laboratory practice applies: appropriate PPE, aseptic technique when reconstituting, and disposal in line with your institution's procedures for copper-containing waste. For in-vitro laboratory research only — not for human or veterinary use.