1. Department of Physiology and Biophysics, Stony Brook University, Stony Brook, New York 11794-8661
2. Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York 11794-5222
3. Ruhr-Universität Bochum, Physikalische Chemie I, Fakultät für Chemie, Universitätsstrasse 150, 44780 Bochum, Germany