1. Department of Life Science, Faculty of Bioscience and Biotechnology, Tokyo Institute of Technology, Nagatsuta, Midori-ku, Yokohama 226, Japan, Department of Physical Chemistry, National Institute of Materials and Chemical Research, Agency of Industrial Science and Technology, MITI, Tsukuba Science City 305, Japan, and Department of Polymer Science, Tokyo Institute of Technology, 2−12−1 O-okayama, Meguro-ku, Tokyo 152, Japan