1. Department of Physiology and Biophysics, Weill Medical College of Cornell University,
New York, New York 10021; Departments of Physics and Chemistry, Université de Montréal,
C. P. 6128, succursale Centre-Ville, Montréal (Québec), Canada H3C 3J7; and Department of Biochemistry
and Structural Biology, Weill Medical College of Cornell University, New York, New York 10021