1. Department
of Biochemistry and Biophysics, University of Rochester Medical Center, Rochester, New York 14642, United States
2. Department
of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, United States
3. IBM T. J. Watson Research Center, Yorktown
Heights, New York 10598, United States
4. Department
of Chemistry, Wabash College, Crawfordsville, Indiana 47933, United States
5. Department
of Physics, University of Arizona, Tucson, Arizona 85721, United States