1. Department of Chemistry, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei, Taiwan 10617, R.O.C., Institute of Chemistry, Academia Sinica, Nankang, Taiwan, R.O.C., and Institute of Molecular Biology, National Chung Hsing University and Department of Medical Genetics, China Medical University Hospital, Taichung, Taiwan, R.O.C.