1. Graduate School of Pharmaceutical Sciences, Tohoku University, Aoba-yama, Aoba-ku, Sendai 980-8578, Japan, Faculty of Advanced Life Science, Frontier Research Center for Post-Genome Science and Technology, Hokkaido University, Kita 21 Nishi 11, Sapporo 001-0021, Japan, and Department of Chemistry and Materials Science, Tokyo Institute of Technology, 2-12-1-H-63 O-okayama, Meguro-ku, Tokyo 152-8551, Japan