1. Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
2. Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita-shi, Osaka 565-0871, Japan
3. Department of Chemistry, Graduate School of Science, and The OCU Advanced Research Institute for Natural Science and Technology (OCARINA), Osaka City University, Sumiyoshi, Osaka 558-8585, Japan
4. Division of Bioscience, Graduate School of Natural Science and Technology/Faculty of Science, Okayama University, 1-1, Naka 3-chome, Tsushima, Okayama 700-8530, Japan