Figure 1 Three- dimensional structure of the HIV-1 protease mixture which includes the inhibitor

Molecular simulation is a powerful tool for supporting various researches on molecules existed in the immediate environment such as molecular design of medicinal and agrichemical drugs, and also new functional nano/bio-materials. For example, in a research of HIV-1 protease, many states where a ligand molecule (inhibitor) bounded at an active site can be calculated precisely, and an inhibited process of protease function can be understood by the aid of the graphical representations (Figure 1). In addition, modification and replacement of the inhibitor (high-throughput virtual screening), high-accurate energy evaluations by using thermal dynamics of the protease-ligand complex, those challenging will be able to contribute to seeking a new medicine which has more powerful and fewer side-effects. Moreover, practical applications to high-speed analysis for large-scale molecular simulation are realized by introducing parallel distributed processing technology to our computational tools.

Figure 2 Figure2 Crystalline structure of aspirin (a) Form I, (b) Form II

In the R & D from medicines to functional materials, one of the common important problems is a prediction method of crystal polymorphism. In other words, when a molecule can be crystallized with some different packing forms, a part of the grown crystals may show unexpected chemical/physical properties and medicinal effect. For example, aspirin is known as analgesic and antipyretic drug, and the second crystal structure “form II” that is slightly different from conventionally-known “form I” was recently discovered (Figure2). Our crystal simulation technology can be used to calculate the lattice energies of these crystalline structures, activated energies of the crystal phase transformation, and the sublimation and melting energies, and then, make it is possible to support bioavailability estimation such as the medicinal effects due to the crystal polymorphism.