1. S. Seo and K. Ishizuka, Institute of Applied Biochemistry, University of Tsukuba, Tsukuba, Ibaraki 305, Japan.
2. M. Okamoto, Tsukuba Institute, Toagousei Corporation Limited, Tsukuba, Ibaraki 305, Japan.
3. H. Seto, Institute of Physical and Chemical Research, Wako, Saitama 351-01, Japan.