GHK Cu Peptide for Skin & Hair Facial Serum & Scalp Solution GHK Cu Copper Peptide 0.5% (topical foam) GHK Cu Peptide Skin Cream Levers.Health GHK Cu Peptide Guide Effects, Dosage, Side Effects 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