The Effect of the Human Peptide GHK on Gene Expression Relevant to Nervous System Function and Cognitive Decline 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 Effect of ascorbate on tachyphylaxis of 30 nM isoproterenol (IP) Download Scientific Diagram Effect of GHK Cu, CuSO4, GHK+CuSO4, and GHK on laccase production. Download Scientific Diagram