Title: A Genetic Algorithm for Pharmacophore Elucidation Author: Gareth Jones Arena Pharmaceuticals Abstract: A genetic algorithm (GA) has been developed for pharmacophore elucidation and the superimposition of sets of flexible molecules. This algorithm, called GAPE (Genetic Algorithm for Pharmacophore Elucidation) is based on the GASP program [1], but incorporates numerous improvements. In particular, many ideas used in the development of the docking program GOLD [2] have been applied to the new algorithm. Additionally, GAPE does not require that all molecules in the input set contain the pharmacophore. The algorithm chooses one molecule to act as a template against which all the other molecules are superimposed, in such a way that pharmacophore features such as donor interaction points, acceptor atoms and ring centres are overlaid. Simultaneously, all structures are conformationally searched. The program incorporates a definition of hydrogen bonding groups catalogued by Mills and Dean [3]. In addition to use in in-house projects the algorithm has been evaluated on a number of publicly available data-sets. 1. G. Jones, P. Willett and R. C. Glen, "A Genetic Algorithm for Flexible Molecular Overlay and Pharmacophore Elucidation," Journal of Computer-Aided Molecular Design 9 (1995) pp.532-549. 2. G. Jones, P. Willett, R. C. Glen, A. R. Leach and R. Taylor, "Development and Validation of a Genetic Algorithm for Flexible Docking," Journal of Molecular Biology 267 (1997) pp.727-748. 3. J.E.J Mills and P.M. Dean, "Three-Dimensional Hydrogen-bond Geometry and Probability Information from a Crystal Survey," Journal of Computer-Aided Molecular Design 10 (1996) pp.607-622.