1. Contribution from the Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, Department of Biochemistry, Molecular Biology, and Cell Biology, Northwestern University, 2153 North Campus Drive, Evanston, Illinois 60208-3300, Department of Chemistry, University of Michigan, 930 North University, Ann Arbor, Michigan 48109-1055, Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405-7102, and Department of Chemistry,...