1. a Department of Biomolecular Engineering, Tokyo Institute of Technology, Nagatsuda, Midori-Ku, Yokohama 226, Japan
2. b Department of Biomolecular Engineering, Tokyo Institute of Technology, Nagatsuda, Midori-Ku, Yokohama 226, Japan
3. c Department of Biomolecular Engineering, Tokyo Institute of Technology, Nagatsuda, Midori-Ku, Yokohama 226, Japan