Conformation of the alpha form of human calcitonin gene-related peptide (CGRP) in aqueous solution as determined by circular dichroism spectroscopy.

Circular dichroism (CD) spectroscopic studies on the alpha form of human calcitonin gene-related peptide (alpha-hCGRP) indicate that, in aqueous solution at 4 degrees C, there is some alpha-helical structure present. This helix involves 8-10 residues of the 28 amino acid, C-terminal tail. The alpha helix is destabilized by denaturants such as guanidinium hydrochloride and increased temperature and is stabilized by the addition of anionic detergents, such as sodium dodecyl sulphate (SDS). In the presence of SDS and 33% trifluoroethanol, nearly all of the residues in the C-terminal tail are in the alpha-helical conformation. These studies indicate that there is sufficient helical structure in aqueous solution to suggest that formation of an amphiphilic helix in the C-terminal tail of alpha-CGRP may be physiologically relevant.