1. Laboratory of Computational Biology, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, United States
2. Department of Sciences, University College Groningen, University of Groningen, 9718 BG Groningen, The Netherlands
3. Department of Chemistry, Brock University, 500 Glenridge Avenue, St. Catharines, Ontario, Canada L2S 3A1
4. Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States