89030 95 5 GHK Cu Gly His Lys Cu Copper Tripeptide 1; Prezatide copper GHK Cu spotlight A copper peptide commonly discussed in research communities for its links to skin appearance, hair interest, and tissue support. At HelixPeptides, we keep things clean, simple, and research focused, with 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 GHK Cu vs AHK Cu: Which Copper Peptide Is More Effective?