1. Biological Chemistry and Bioorganic Chemistry, Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo 060-0810, Department of Biochemistry, Kyorin University School of Medicine, Mitaka 181-1611, Communications Research Laboratory, Kansai Advanced Research Center, Kobe 651-2492, and Department of Biochemistry, Asahikawa Medical College, Asahikawa 078-8510, Japan