1. Institute for Protein Research; Osaka University; 3-2, Yamadaoka Suita Osaka 565-0871 Japan
2. Department of Chemistry, Graduate School of Medical Science; Kyoto Prefectural University of Medicine; Kita-ku Kyoto 603-8334 Japan
3. Department of Life Science, Graduate School of Science and Technology; Kobe University; 1-1 Rokkodai-cho Nada-ku Kobe 657-8501 Japan
4. Department of Medicinal Chemistry; Kyoto Pharmaceutical University; Yamashina-ku Kyoto 607-8412 Japan