On the role of the C-terminus of α-calcitonin-gene-related peptide (αCGRP). The structure of des-phenylalaninamide37-αCGRP and its interaction with the CGRP receptor

alpha-Calcitonin-gene-related peptide (alpha CGRP) lacking its C-terminal phenylalaninamide residue was found not to bind to its receptor as did full-length (amidated) alpha CGRP. Investigation of the structure of these peptides by c.d. and n.m.r. revealed no significant difference, so it seemed that the effect of deleting the C-terminal phenylalaninamide on the biological activity of alpha CGRP was not by disruption of the peptide's structure. Thus the C-terminal phenylalaninamide is an important factor in this ligand-receptor interaction, and the group itself may interact directly with the receptor.