1. Department of Biochemistry, Cellular, and Molecular Biology, University of Tennessee, Knoxville, Tennessee 37996-0840, Laboratory of Structural Biology, MR-01, National Institute of Environmental Health Sciences, National Institutes of Health, Box 12233, Research Triangle Park, North Carolina 27709, Dana-Farber Cancer Institute and Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, and Department of Chemistry, University at Buffalo, 457C...