1. Department of Chemistry The University of Tokyo Tokyo 113-0033 Japan
2. Department of Neurology Kyoto University Hospital Kyoto 606-8507 Japan
3. Institute for Protein Research Osaka University Osaka 565-0871 Japan
4. Graduate School of Science Osaka Metropolitan University Osaka 558-8585 Japan
5. Department of Chemistry and Biotechnology Tottori University Tottori 680-8552 Japan