1. Department of Biomolecular Engineering, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8501, Japan, National Institute for Materials Science, 3-13 Sakura, Tsukuba, Ibaraki 305-0003, Japan, and Department of Chemistry and Chemical Biology, Gunma University, 1-5-1 Tenjin-cho, Kiryu, Gunma 376-8515, Japan