Molecular crystal structure of the tripeptide GHK Cu. In solution, Download Scientific Diagram Essential GHK Cu Serum: What It Is, How It Works, and Why It Matters f Bacteriostaticwater.com GHK Cu Peptide Therapy: The Definitive Clinical Guide to Gene Modulation, Protocols, and Efficacy GHK Cu is a naturally occurring tripeptide in human plasma. Levels average 200 ng ml at age 20 and drop to 80 ng ml by age 60 (Pickart et al., 2020). That decline tracks with