AHK-Cu Research Guide

Overview

AHK-Cu (also referred to in the literature and industry as Copper Tripeptide-3) is a synthetic copper-binding tripeptide complex composed of the amino acid sequence alanine-histidine-lysine (Ala-His-Lys) coordinated to a divalent copper ion (Cu²⁺). It is registered under CAS number 682809-81-0 (hydrochloride salt form), with a free-base molecular formula reported in the chemical literature as approximately C₁₅H₂₄CuN₆O₄ and a molecular weight in the range of approximately 415–452 g/mol depending on salt form and hydration state.

AHK-Cu is structurally related to the more extensively characterized copper tripeptide GHK-Cu (glycyl-L-histidyl-L-lysine copper complex), differing by a single N-terminal residue substitution — alanine in place of glycine. This close structural relationship has made comparative research between AHK-Cu and GHK-Cu a recurring theme in the published tripeptide-copper complex literature, particularly in studies of dermal papilla cell biology and hair follicle research models. Available for research at Iron Peak Peptides: AHK-Cu.

Copper-binding tripeptides of this general structural class belong to a broader family of research compounds sometimes described as copper peptide complexes, studied for their proposed roles in extracellular matrix regulation, connective tissue biology, and cellular signaling relevant to tissue remodeling research. This guide summarizes the published, peer-reviewed literature specific to AHK-Cu and closely related tripeptide-copper complexes, and is intended strictly as a citation-based research resource rather than a usage, dosing, or cosmetic-formulation guide.

Molecular Profile & Structure

AHK-Cu is formed through the coordination of a Cu²⁺ ion by the tripeptide backbone of alanine, histidine, and lysine, a structural motif in which the histidine imidazole ring and the peptide’s terminal amine and carboxylate groups are proposed to participate in metal coordination, analogous to the well-characterized coordination geometry described for GHK-Cu. This copper-binding architecture is of particular interest to structural and coordination chemistry research examining how short peptide sequences can selectively chelate transition metal ions relevant to cellular physiology.

• Common names: AHK-Cu, Copper Tripeptide-3, Ala-His-Lys copper complex
• Amino acid sequence: Alanine – Histidine – Lysine, complexed with Cu²⁺
• Peptide class: Copper-binding tripeptide complex
• Molecular formula: Approximately C₁₅H₂₄CuN₆O₄ (free base); C₁₅H₂₅ClCuN₆O₄ (hydrochloride salt)
• Molecular weight: Approximately 415.9 g/mol (free base); approximately 451–452 g/mol (hydrochloride salt)
• CAS number: 682809-81-0 (hydrochloride form)
• Structural analog: GHK-Cu (Gly-His-Lys copper complex), differing by a single N-terminal residue
• Appearance: Blue to blue-violet lyophilized powder, consistent with copper(II) complex coloration
• Storage: Store lyophilized peptide-copper complex at -20°C, protected from moisture and light. Reconstituted solutions should be stored at 2-8°C and used within the timeframe established by the supplying laboratory; repeated freeze-thaw cycling should be avoided to preserve complex integrity.

Mechanism of Action

Published mechanistic research on AHK-Cu has focused primarily on its effects on dermal papilla cells (DPCs) and human hair follicles studied ex vivo. In a foundational in vitro study, AHK-Cu treatment across a concentration range of 10^-12 to 10^-9 M was reported to stimulate proliferation of cultured dermal papilla cells and to elevate the ratio of Bcl-2 to Bax protein expression, an indicator of anti-apoptotic signaling balance, while concurrently reducing the levels of cleaved (activated) caspase-3 and cleaved PARP, both markers of active apoptotic proteolysis. Together, these findings were interpreted as evidence that AHK-Cu exerts a pro-proliferative and anti-apoptotic effect on dermal papilla cells in vitro.

The same study reported that AHK-Cu elevated production of vascular endothelial growth factor (VEGF) by dermal fibroblasts, while decreasing secretion of transforming growth factor-beta1 (TGF-β1) — a cytokine associated with growth-inhibitory and pro-fibrotic signaling in various tissue contexts. Elevated VEGF production is proposed in the literature to support vascularization processes relevant to hair follicle and dermal papilla research, while reduced TGF-β1 secretion has been proposed as a mechanism potentially relevant to modulating growth-inhibitory signaling within the dermal papilla microenvironment.

Because AHK-Cu shares its core coordination chemistry and general mechanistic themes with the more extensively studied GHK-Cu, broader review literature on copper tripeptide complexes has proposed additional mechanisms relevant to this structural class, including modulation of matrix metalloproteinase (MMP) activity alongside their tissue inhibitors (TIMPs), stimulation of glycosaminoglycan and collagen synthesis by dermal fibroblasts, and antioxidant activity related to copper’s role as a cofactor in enzymes such as superoxide dismutase. Researchers examining AHK-Cu specifically have generally proposed that its close structural similarity to GHK-Cu supports a shared, though not identical, mechanistic framework, while noting that direct head-to-head mechanistic data specific to AHK-Cu (as opposed to GHK-Cu) remains comparatively limited in the published literature.

Key Research Findings

The principal published research directly examining AHK-Cu was conducted by Kang and colleagues, who evaluated the tripeptide-copper complex in both an ex vivo human hair follicle organ culture model and in cultured human dermal papilla cells. This study reported that AHK-Cu stimulated elongation of human hair follicles maintained in ex vivo culture and increased proliferation of dermal papilla cells in vitro, with the proposed mechanism involving both enhanced proliferation and reduced apoptosis of dermal papilla cells, alongside elevated VEGF and reduced TGF-β1 production by dermal fibroblasts (Kang et al., 2007).

Because AHK-Cu belongs to the broader copper tripeptide complex family that also includes GHK-Cu, foundational and review research on GHK-Cu provides important comparative context for interpreting AHK-Cu’s proposed activity. Pickart and colleagues, in a review of GHK’s role in tissue remodeling, summarized decades of published research describing GHK-Cu’s proposed effects on collagen and glycosaminoglycan synthesis, wound healing model outcomes, and modulation of gene expression programs associated with tissue repair and antioxidant defense (Pickart, 2008).

A more recent comprehensive review by Pickart and Margolina examined the regenerative and protective actions of GHK-Cu across multiple tissue and cell-line models, cataloguing published research on its proposed roles in modulating gene expression related to extracellular matrix remodeling, anti-inflammatory signaling, and cellular protection against oxidative stress — mechanistic themes that inform ongoing comparative research into structurally related copper tripeptides such as AHK-Cu (Pickart & Margolina, 2018).

Comparative industry and academic literature examining the structural distinction between AHK-Cu and GHK-Cu has noted that, while both tripeptides share the histidine-lysine copper-coordinating core, the N-terminal alanine substitution in AHK-Cu is proposed to influence complex stability and receptor or binding-site interactions relative to the glycine-containing GHK-Cu, an area that continues to be examined in structure-activity relationship research on short copper-binding peptides.

Broader tripeptide wound-healing review literature has situated copper tripeptide complexes, including AHK-Cu and GHK-Cu, within a larger category of bioactive tripeptides studied across the phases of wound healing, from early inflammatory signaling through proliferative fibroblast activity and later-stage tissue remodeling, providing a comparative framework for researchers evaluating copper-peptide mechanisms alongside other short bioactive peptide classes.

Research Applications

AHK-Cu is used in laboratory research primarily within dermal papilla cell biology and hair follicle organ culture models, where it serves as a tool compound for investigating proliferation and apoptosis signaling pathways relevant to hair follicle physiology research. Specific research applications include in vitro dermal papilla cell proliferation assays, ex vivo human hair follicle culture systems used to examine follicle elongation as a research endpoint, and studies of VEGF and TGF-β1 secretion by dermal fibroblasts as downstream signaling readouts.

Given its structural relationship to GHK-Cu, AHK-Cu is also used in comparative copper tripeptide research examining structure-activity relationships among short copper-binding peptides, including coordination chemistry studies characterizing metal-binding geometry and stability, and cell-based assays comparing the relative potency of AHK-Cu against GHK-Cu and other tripeptide-copper analogs across various cell-line and tissue models.

Researchers in the broader tissue remodeling and connective-tissue biology fields also study copper tripeptide complexes such as AHK-Cu as tool compounds for examining copper-dependent enzymatic processes, extracellular matrix component synthesis, and antioxidant defense pathways, frequently positioning these compounds alongside other classes of peptide-based tissue-remodeling research tools, such as growth-factor-derived and matrix-mimetic peptides, in comparative in vitro study designs.

References

1. Kang YJ, Eun HC, Cho KH, Kim KH. (2007). The effect of tripeptide-copper complex on human hair growth in vitro. Archives of Pharmacal Research.
2. Pickart L. (2008). The human tri-peptide GHK and tissue remodeling. Journal of Biomaterials Science, Polymer Edition.
3. Pickart L, Margolina A. (2018). Regenerative and Protective Actions of the GHK-Cu Peptide in the Light of the New Gene Data. International Journal of Molecular Sciences.
4. Exploring the Role of Tripeptides in Wound Healing and Skin Regeneration. International Journal of Medical Sciences.