1. Research Reactor Institute, Kyoto University, Kumatori, Osaka 590-0494, Japan, Department of Physiology, Jichi Medical University, Shimotsuke, Tochigi 329-0498, Japan, Protein Design Laboratory, Yokohama City University, Tsurumi, Yokohama 230-0045, Japan, Quantum Beam Science Directorate, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan, and Department of Technology, Ibaraki University, Hitachi, Ibaraki 316-8511, Japan