Not too big. Not too small. Because of their intermediate size, macrocyclic peptides combine the potency and precise targeting of an antibody or biologic therapy with the stability and ease of administration of a Intermediate Cu(II) Thiolate Species in the Reduction of Cu(II)GHK by Glutathione: A Handy Chelate for Biological Cu(II) Reduction Inorganic Chemistry Glycyl L histidyl L lysine Cu2+ (GHK Cu) Attenuates CuSO4 or LPS induced inflammation in Zebrafish larvae model ScienceDirect An injectable hydroxyapatite microsphere filler loaded with GHK Cu tripeptide for anti Inflammatory and antioxidant ScienceDirect Ghk Cu Tolerance Desensitization Effectiveness Loss