1. Department
of Chemistry, Wesleyan University, Lawn
Avenue, Middletown, Connecticut 06459, United States
2. Centre d’Ingéniere des Proteines, Université de Liège, B-4000 Sart Tilman,
Liège, Belgium
3. Department
of Pharmacology, University of North Carolina, Chapel Hill, North Carolina 27599-7365, United States