Five Peptides Every Endurance Athlete Should Understand Your body made this peptide every day until you turned 30. Then it stopped. GHK Cu (copper peptide) is a naturally occurring tripeptide discovered in 1973. At age 20, your plasma levels sit Viral claim says GHK Cu reset nearly 4,000 genes to a younger state and increased collagen production in a preclinical study. This refers to research on GHK Cu, a naturally occurring copper binding peptide that GHK Cu Cooper Peptide: The Complete Skin & Repair Guide (2026)