1. Division of Advanced Science and Biotechnology, Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871, Japan
2. WPI-Immunology Frontier Research Center, Osaka University, Suita, Osaka 565-0871, Japan
3. Laboratoie de Chimie, ENS de Lyon, 46 allée d'Italie, Lyon Cedex 07, France 69364