A comparative structural study of apamin and related bee venom peptides.

Secondary structure analysis of apamin, mast cell degranulating peptide, tertiapin and secapin has been attempted, based on parameters produced by Levitt (Biochemistry (1978) 17, 4277--4285). The structural model, recently advanced for apamin, based on Chou and Fasman's parameters was confirmed. The predicted structure for mast cell degranulating peptide is almost spherical with the eight positive centres evenly distributed over the surface. On the basis of this analysis and related spectroscopic evidence, it is suggested that these four peptides share a common folding pattern, which is centered on a beta-turn covalently linked to an alpha-helical segment by two disulphide links (one disulphide link in the case of secapin). It is further suggested that apamin, mast cell degranulating peptide and tertiapin form a single molecular class.