Intermediate Cu(II) Thiolate Species in the Reduction of Cu(II)GHK by Glutathione: A Handy Chelate for Biological Cu(II) Reduction Inorganic Chemistry Copper peptides explained what are the differences between copper peptides and GHK CU peptides? What they actually do for the skin in terms of repair and collagen, and what you can and cant mix GHK Cu (copper peptide) used topically is one of the most well studied skin repair peptides. Here's how it helps the skin, in practical terms: 1. Boosts collagen & elastin GHK Cu signals your skin Does GHK Cu Really Work? 40 Years of Research Reviewed