16. Receptor Regulation Principles of Pharmacology Study Guide 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 Rigid flexible nanocarriers loaded with active peptides for antioxidant and anti inflammatory applications in skin ScienceDirect