Molecular crystal structure of the tripeptide GHK Cu. In solution, Download Scientific Diagram GHK Cu is a naturally occurring copper binding peptide that plays a major role in tissue repair and remodeling, with a strong focus in research on skin and hair biology. It works by signaling Copper peptide GHK Cu Wikipedia 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