What Is GHK-Cu (Copper Peptide)? GHK-Cu, commonly known as Copper Peptide, is a naturally occurring tripeptide composed of three amino acids: Glycine Histidine Lysine When this peptide binds to a copper ion, it forms the biologically active compound known as GHK-Cu (Glycyl-L-Histidyl-L-Lysine Copper). Discovered in 1973, GHK-Cu is found naturally in human plasma, saliva, and