1. Biochemical Research Laboratories, Ezaki Glico Co., Ltd., Nishiyodogawa-ku, Osaka 555, Japan
2. Nagase Biochemicals Co., Ltd., Nagatano-cho, Fukuchiyama, Kyoto 620, Japan
3. Department of Biotechnology, Faculty of Engineering, Osaka University, Yamadaoka, Suita, Osaka 565, Japan