A molecular orbital study of amiloride

The application of stereolithography to the fabrication of accurate molecular models

The process of stereolithography, which automatically fabricates plastic models from designs created in certain computer-aided design programs, has been applied to the production of accurate plastic molecular models. Atomic coordinates obtained from quantum mechanical calculations and from neutron diffraction data were used to locate spheres in the I-DEAS CAD program with radii proportional to the appropriate van der Waals radii. The sterolithography apparatus was used to build the models using a photosensitive liquid resin, resulting in hard plastic models that accurately represent the computed or experimental input structures. Three examples are given to illustrate how the models can be used to interpret experimental structure-activity data for systems of biological importance or host-guest chemistry: (1) Interpretation of kinetic data for the formation of a stable blocking complex between amiloride analogs and the epithelial sodium channel, (2) interpretation of binding and neural activity data for the interaction of certain amino acids and their analogs at the L-alanine taste receptor of the channel catfish, and (3) interpretation of shape selectivity and rate acceleration in cyclodextrin catalysis using models of the neutron diffraction structure of beta-cyclodextrin and of the transition state for the cleavage of phenyl acetate by the secondary hydroxyl oxygen of beta-cyclodextrin.