GHK Cu as a multifunctional copper peptide: synthesis routes, process engineering and emerging applications Systems Microbiology and Biomanufacturing Springer Nature Link The Effect of the Human Peptide GHK on Gene Expression Relevant to Nervous System Function and Cognitive Decline Shop Pendragon Peptides GHK Cu may Prevent Oxidative Stress in Skin by Regulating Copper and Modifying Expression of Numerous Antioxidant Genes