GHK Cu Topical vs Injection Which is the Better Copper Peptide Form? Defy GHK Cu (glycyl L histidyl L lysine) is a naturally occurring copper binding peptide found in human plasma. As levels decline with age, so may its support of the biological processes involved in collagen production, skin 7% GHK Cu Cosmetic Ingredient Accelerant Skin Biology 15 ml GHK Cu Peptide: Hair Regrowth for Thinning & Alopecia GHK Copper Peptide GHK Cu Tripeptide 1