1. Biophysical Chemistry Laboratory, RIKEN, Wako, Saitama 351-0198, Japan, Institute of Materials Science, University of Tsukuba, Tsukuba, Ibaraki 305-8573, Japan, and Department of Applied Biological Chemistry, Faculty of Agriculture, Osaka Prefecture University, 1-1 Gakuen-cho, Sakai, Osaka, 599-8531 Japan