GHK Cu vs AHK Cu: Which Copper Peptide Is More Effective? GHK CU GHKCu (glycyl L histidyl L lysine copper) is a naturally occurring copper peptide found in the human body, particularly in plasma, saliva, and urine. It plays a key role in skin regeneration by promoting Copper Peptide Duo GHK Cu Anti Aging Serum & Moisturizer Peptide Calculator Accurate Peptide Dosing Made Simple Free Peptide Calculator for 150 Peptides Peptide Schedule