GHK Cu: The Copper Peptide And The Claims Around It GHK Cu is a naturally occurring copper binding tripeptide found in human plasma. Mechanistically, it's linked to tissue repair signaling, immune modulation, glycosaminoglycan and collagen Intermediate Cu(II) Thiolate Species in the Reduction of Cu(II)GHK by Glutathione: A Handy Chelate for Biological Cu(II) Reduction Inorganic Chemistry Blockade of glucagon receptor induces cell hypersecretion by hyperaminoacidemia in mice Nature Communications The Effect of the Human Peptide GHK on Gene Expression Relevant to Nervous System Function and Cognitive Decline