1. Department of Chemistry, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan, National Institute of Genetics, Yata, Mishima-shi, Shizuoka 411-8540, Japan, The Graduate University for Advanced Studies, Myodaiji, Okazaki 444-8585, Japan, and Rigaku Corporation, 3-9-12 Matsubaracho, Akishima, Tokyo 196-8666, Japan