Tateno (Life Science Group in CCS, University of Tsukuba) and Matsumura (Osaka University) revealed that in T1 lipase (an enzyme), Na+ interacts with a hydrophobic aromatic ring (Phe16) and hydrophilic amino acid residues (Ser and His), leading to a stable core structure in the buried region of the enzyme and the active site for the enzymatic reaction. This is the first report of functional mechanisms of the interaction between Na+ and an aromatic ring in biological macromolecules. This analysis was performed by using computer simulations such as advanced ab initio quantum mechanics calculations and molecular dynamics simulations with the use of a novel calculation scheme developed in this study. Highly- parallelized supercomputers such as the PACS-CS system of CCS, etc. were employed for the calculations.

Reference
Hagiwara, Y., Matsumura, H., and Tateno, M.: Functional roles of a structural element involving Na+-pi interactions in the catalytic site of T1 lipase revealed by molecular dynamics simulations: J. Ame. Chem. Soc., in press.
http://pubs.acs.org/doi/abs/10.1021/ja903451b