GHK Cu: The Elegant Copper Peptide for Skin and Scalp Renewal Renew Vitality Copper peptide (GHK Cu) SIELC Technologies Your copper peptide product should be this exact blue. If it isn't, you already have your answer. GHK Cu is blue because of coordination chemistry, not dye. The Cu ion at the center GHK Cu as a multifunctional copper peptide: synthesis routes, process engineering and emerging applications Systems Microbiology and Biomanufacturing Springer Nature Link The copper(II) binding tripeptide GHK, a valuable crystallization and phasing tag for macromolecular crystallography