Copper Peptide Regenerating Serum for Glowing Skin and Hair 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 Copper Peptide Duo GHK Cu Anti Aging Serum & Moisturizer Most people think skincare works at the surface level. But healthy skin function starts much deeper than a temporary glow. GHK Cu is a naturally occurring copper binding tripeptide that is already found