GHK-Cu

Overview

GHK-Cu (glycyl-L-histidyl-L-lysine:copper(II)) is a naturally occurring tripeptide–copper complex first identified in human plasma by Dr. Loren Pickart in 1973. Pickart discovered that albumin isolated from young human blood (ages 20–25) was able to stimulate old liver tissue to synthesize proteins at a rate comparable to young tissue. The active factor responsible for this rejuvenating effect was subsequently identified as the tripeptide GHK bound to a copper(II) ion.

GHK-Cu is present in human plasma, saliva, and urine. Plasma concentrations decline with age — from approximately 200 ng/mL at age 20 to roughly 80 ng/mL by age 60. This age-related decline has been central to the hypothesis that GHK-Cu depletion contributes to the reduced regenerative capacity observed with aging.

What distinguishes GHK-Cu from many other peptides studied in regenerative medicine is the breadth and depth of its gene-modulatory effects. A landmark 2010–2014 series of studies using the Connectivity Map (cMap) gene expression database demonstrated that GHK-Cu modulates the expression of over 4,000 human genes — approximately 6% of the human genome. Many of these genes are associated with tissue remodeling, antioxidant defense, anti-inflammatory responses, and stem cell recruitment.

GHK-Cu has been commercially available in cosmetic formulations since the 1990s and is one of the most well-characterized peptides in dermatological research. It is also studied as an injectable peptide in biohacking and anti-aging communities.

Amino Acid Sequence

GHK-Cu consists of three amino acids complexed with a copper(II) ion:

Gly-His-Lys:Cu²⁺

• Molecular formula (free peptide): C₁₄H₂₄N₆O₄
• Molecular weight (free peptide): 340.38 g/mol
• Molecular weight (copper complex): 401.93 g/mol
• CAS Number: 49557-75-7 (GHK); 89030-95-5 (GHK-Cu)

The copper ion is coordinated through the nitrogen atoms of the glycine amino terminus, the histidine imidazole ring, and the deprotonated amide nitrogen between glycine and histidine. This coordination geometry gives the complex high stability at physiological pH while allowing the copper to be released at sites of tissue damage.

Mechanism of Action

GHK-Cu operates through several distinct but interconnected biological mechanisms:

Copper Delivery and Metalloenzyme Activation

The peptide serves as a bioavailable copper delivery system. Copper is an essential cofactor for numerous enzymes involved in tissue repair:

• Lysyl oxidase — required for collagen and elastin cross-linking
• Superoxide dismutase (SOD) — a key antioxidant enzyme
• Cytochrome c oxidase — mitochondrial electron transport
• Tyrosinase — melanin synthesis

By delivering copper to wound sites, GHK-Cu activates these metalloenzymes, accelerating the biochemical processes underlying tissue remodeling.

Gene Expression Modulation

The most significant finding in GHK-Cu research emerged from Connectivity Map analyses by Pickart, Campbell, and colleagues. GHK-Cu was shown to:

• Upregulate 1,584 genes and downregulate 2,548 genes in human cell cultures
• Shift gene expression patterns in aged tissue toward profiles resembling younger tissue
• Suppress genes associated with metastasis (particularly in colon cancer gene signatures)
• Activate genes involved in the ubiquitin-proteasome pathway, facilitating removal of damaged proteins

Key gene categories affected include extracellular matrix remodeling, DNA repair, antioxidant response, anti-inflammatory pathways, and nervous system support.

Collagen and Extracellular Matrix Remodeling

GHK-Cu stimulates production of collagen types I, III, and IV, as well as glycosaminoglycans (GAGs), decorin, and other ECM components. Simultaneously, it upregulates matrix metalloproteinases (MMPs) that break down damaged ECM, and tissue inhibitors of metalloproteinases (TIMPs) that prevent excessive degradation. This dual action promotes organized tissue remodeling rather than disordered scarring.

Anti-inflammatory Signaling

GHK-Cu reduces the expression of pro-inflammatory cytokines including interleukin-6 (IL-6) and transforming growth factor beta-1 (TGF-β1) when elevated. It also suppresses oxidative damage markers such as ferritin heavy chain and promotes expression of antioxidant genes.

Stem Cell Attraction

Research has demonstrated that GHK-Cu acts as a chemoattractant for mesenchymal stem cells, mast cells, and macrophages — key cell types involved in tissue repair and remodeling.

Research Summary

Pharmacokinetics

• Plasma half-life: Approximately 30–60 minutes in human plasma
• Copper binding affinity: Log K = 16.44 (strong binding at physiological pH)
• Natural plasma concentration: ~200 ng/mL (age 20), declining to ~80 ng/mL (age 60)
• Degradation: Broken down by aminopeptidases in plasma; copper is redistributed to tissue stores
• Topical absorption: Demonstrated skin penetration in cream formulations; exact bioavailability varies with vehicle
• Stability: Stable in aqueous solution at pH 5–7; degrades in strongly acidic or alkaline conditions

GHK-Cu's relatively short half-life is offset by its ability to trigger durable downstream gene expression changes. The peptide acts as a signaling molecule rather than requiring sustained plasma levels for biological effect.

Dosing Protocols

The following dosing information is compiled from published research and community discussion for educational purposes only.

Subcutaneous Protocol (Systemic)

Key Points

• Route: Subcutaneous injection or topical application
• Cycle: 30 days on, 30 days off
• Topical: 0.1–1% concentration in cream/serum, applied 1–2x daily
• Injection timing: Once daily, morning
• Often combined with: Matrixyl, Argireline for skin rejuvenation protocols

Common Discussion Topics

1. Topical vs. injectable — GHK-Cu is widely available in topical skincare products (serums, creams). Injectable use is discussed in biohacking communities for systemic anti-aging effects, though topical remains the most common route.

2. Anti-aging gene reset — The Connectivity Map findings showing reversal of age-related gene expression patterns are among the most-cited results in the peptide community.

3. Hair loss — Studies showing hair follicle stimulation comparable to minoxidil generate significant interest, particularly for topical scalp application.

4. Wound healing stacking — GHK-Cu is frequently discussed alongside BPC-157 and TB-500 for tissue repair protocols.

5. Copper toxicity concerns — Some discussion around whether systemic copper supplementation via GHK-Cu injection could lead to excess copper accumulation, though the amounts delivered by typical peptide dosing are far below toxic thresholds.

6. Cosmetic vs. research-grade — The distinction between cosmetic-grade GHK-Cu products (widely available) and research-grade lyophilized peptide is a common topic.

Related Compounds

• BPC-157 — a pentadecapeptide studied for tissue repair through different mechanisms; often discussed alongside GHK-Cu for healing applications
• TB-500 (Thymosin Beta-4) — another tissue-repair peptide that promotes cell migration and angiogenesis
• Epithalon — a tetrapeptide studied for anti-aging through telomerase activation; sometimes paired with GHK-Cu in anti-aging discussions
• Copper Peptide AHK-Cu — a related copper tripeptide (Ala-His-Lys:Cu) with similar but less-studied properties
• Matrixyl (Palmitoyl Pentapeptide-4) — a cosmetic peptide that stimulates collagen production through different pathways