Coordination geometry of the copper(II) peptide core obtained by QM MM Download Scientific Diagram Theoretical study of copper binding to GHK peptide ScienceDirect Theoretical study of copper binding to GHK peptide ScienceDirect 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 Copper peptide GHK Cu Wikipedia