1. Faculté de Pharmacie, Centre de Biochimie Structurale, CNRS UMR C9955, INSERM U414, 34060 Montpellier Cedex 2, France, Peptide Institute, Inc., 4-1-2 Ina, Minoh, Osaka 562, Japan, Institut de Biologie Structurale, 41 avenue des Martyrs, 38027 Grenoble Cedex 1, France, and Institute for Protein Research and Faculty of Pharmaceutical Sciences, Osaka University, Suita, Osaka 565, Japan