1. Department of Applied Biological Chemistry, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan, Department of Biotechnology, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan, and Department of Chemistry, Tokyo Institute of Technology, 2-12-1, O-okayama, Meguro-ku, Tokyo 152-8551, Japan