[Applications of the Fragment Molecular Orbital Method in Drug Discovery]

Recently, ab initio quantum mechanical calculations have been applied to large molecules, including biomolecular systems. The fragment molecular orbital (FMO) method is one of the most efficient approaches for the quantum mechanical investigation of such molecules. In the FMO method, dividing a target molecule into small fragments reduces computational effort. The clear definition of inter-fragment interaction energy (IFIE) as an expression of total energy is another valuable feature of the FMO method because it provides the ability to analyze interactions in biomolecules. Thus, the FMO method is expected to be useful for drug discovery. This study demonstrates applications of the FMO method related to drug discovery. First, IFIE, according to FMO calculations, was used in the optimization of drug candidates for the development of anti-prion compounds. The second example involved interaction analysis of the human immunodeficiency virus type 1 (HIV-1) protease and a drug compound that used a novel analytical method for dispersion interaction, i.e., fragment interaction analysis based on LMP2 (FILM).