Affiliation: | 1. Division of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305‐8571 (Japan), Fax: (+81)?29‐853‐4237;2. Department of Chemistry, Graduate School of Science, The University of Tokyo, Hongo, Bunkyo‐ku 113‐0033 (Japan);3. Present Address: Laboratory of Bioscience, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, Kanda‐Surugadai, Chiyoda‐ku, Tokyo 101‐0062 (Japan) |