GHK-Cu is a naturally occurring tripeptide (Glycyl-L-Histidyl-L-Lysine) that binds to copper ions. Discovered in human plasma, it is widely studied in biochemistry for its role in cellular signaling, extracellular matrix maintenance, and antioxidant support. In vitro and non-clinical literature often evaluates its affinity for supporting collagen production and tissue remodeling pathways.