Affiliation: | 1. Institut de Chimie Biologique, Universite d''Aix-Marseille, Place V. Hugo, 13331 Marseille, Cedex 3, France;2. Centro di Studi sui Biopolimeri, CNR, Instituto de Chimica Organica, Via Marzolo, 1-35100 Padova, Italy;3. Stanford Magnetic Resonance Laboratory, Stanford University, Stanford, CA 94305, USA |