GHK Cu for Skin & Wound Healing: Current Evidence Meeting Point Health The Effect of the Human Peptide GHK on Gene Expression Relevant to Nervous System Function and Cognitive Decline Copper, Collagen, and Controversy: Inside the GHK Cu Buzz 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 The Effect of the Human Peptide GHK on Gene Expression Relevant to Nervous System Function and Cognitive Decline