PLASTIC MODELS OF PROTEINS AND NUCLEIC ACIDS FOR EDUCATION. Marilyn D. Yoder, University of Missouri-Kansas City, School of Biological Sciences, Kansas City, MO 64110 USA and Robert E. Smith, Allied Signal, Kansas City, MO 64141 USA

A method to manufacture plastic models of proteins and nucleic acids of known three-dimensional structure has been developed for both research and educational purposes. The plastic models were made using stereolithography (SL) and selective laser sintering (SLS) techniques. Ball-and-stick, a-carbon backbone, solvent accessible surface, and ribbon models have been constructed.

The technique has been adapted from the automotive and aerospace industries where SL and SLS are commonly used to prototype manufacturing designs as plastic models. A computer-directed laser maps out the topology of the biopolymer at the surface of either a light sensitive resin (in the case of SL) or a block of nylon powder (in the case of SLS). Upon irradiation by the laser, either the light sensitive resin is converted to a solid polymer, or the nylon powder is fused, or sintered. The laser is controlled by an ISO 9001 compatible computer file, the stl file, that contains the topology of the biopolymer represented as a set of triangles. The normals of each triangle must be pointed outward and the vertices listed in counterclockwise order when looking at the object from the outside. The stl data are used by a slicing algorithm to determine the cross sectional areas of the model to be built. A library of stl files has been calculated from structural data from the Brookhaven PDB and stored on CD-ROM for distribution.

The plastic models are approximately 10 cm in the longest dimension and are lightweight and very portable. They have been used in classroom instruction for students from the sixth grade (approximately 12 years of age) to the graduate school level. A stainless steel casting of a SL model of subtilisin was made for the Science in American Life exhibit in the Smithsonian Institution's Museum of American History (Washington, D.C. USA) and is used with an interactive computer to teach the principles of protein docking.