Molecular models for the stereochemical structures of fumonisin B-1 and B-2

Assessment of the structural configuration of fumonisin B-1 (FB1) and B-2 (FB2) would allow better understanding of the behavior of these molecules during isolation or other handling procedures, and their interaction with binding sites or antibodies. Molecular models of the absolute configurations of FB1 and FB2 were calculated using a CAChe WorkSystem(TM). The electrostatic potential energy surfaces of the minimum potential energy conformations for FB1 and FB2 also were obtained. The models reveal that the backbone and acid side chains for FB1 and FB2 form a spherical globular model. The folded region forms a cage-like feature. It is this feature that suggests that these molecules may be potential chelators. The electrostatic potential surfaces show that most of the exposed surfaces of these molecules are hydrophobic in nature, and that there is a distinct difference between the electrostatic potential surfaces of the FB1 models resulting from the stereochemistry proposed by Shier et al. (1995) and Boyle and Kishi (1995a). The electrostatic surfaces clearly show a different orientation of the hydrophobic tail region of the backbone for FB2 than in the models for FB1.