GHK Cu Copper Peptide: Dosage, Before and After Results, and How It Works Perfect B GHK Cu vs NAD+: Which Longevity Peptide Should You Take or Stack? Topical GHK Cu: Skin Benefits, Best Forms, and Where to Buy 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