1. School of Pharmaceutical Sciences, Showa University, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo 142, Japan
2. School of Chemistry, The University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
3. The Laboratory of Molecular Biophysics, Rex Richards Building, South Parks Road, Oxford OX1 3QU, UK
4. The Oxford Centre for Molecular Sciences, New Chemistry Building, South Parks Road, Oxford OX1 3QT, UK
5. Division of Human Retroviruses, Center for Chronic Viral Diseases, Faculty of Medicine, Kagoshima University, Kagoshima 890, Japan