Synthesis and Steroidogenic Activity of Covalently Dimerized Corticotropin (ACTH) Fragments

The chemical synthesis by classical methods in solution of a dimer of the sequence 1 to 24 of adrenocorticotropin(ACTH) is described. The two monomers were covalently linked through their C‐termini, using lysine amide as spacer. Dimerization did not improve significantly the potency of the agonist ACTH‐(1–24), while it strongly potentiated the antagonistic effect of the fragments ACTH‐(11–24) and ACTH‐(7–24) in the stimulation of steroidogenesis in isolated adrenal cells. The results seem to imply a microaggregation of the receptors at the adrenal cell surface.