1. Department of Chemistry, Wesleyan University, Middletown, Connecticut 06459
2. Faculty of Pharmaceutical Sciences, Jyosai International University, 1 Gumyo, Togane-shi, Chiba 283-8555, Japan
3. Centre d'Ingeniere des Proteines et Laboratoire d'Enzymologie, Université de Liège, B-4000 Sart Tilman, Liège 1, Belgium