Frontiers Exploring the beneficial effects of GHK Cu on an experimental model of colitis and the underlying mechanisms GHK Cu may Prevent Oxidative Stress in Skin by Regulating Copper and Modifying Expression of Numerous Antioxidant Genes Not too big. Not too small. Because of their intermediate size, macrocyclic peptides combine the potency and precise targeting of an antibody or biologic therapy with the stability and ease of administration of a Expression and Purification of Recombinant GHK Tripeptides Are Able to Protect against Acute Cardiotoxicity from Exposure to Waterborne Copper in Zebrafish