1. Department of Chemistry, Northern Arizona University, Box 5698, Flagstaff, Arizona 86011-5698, Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic Foundation, 9500 Euclid Avenue, Cleveland, Ohio 44195, Department of Chemistry, Cleveland State University, Cleveland, Ohio 44115, and Structural Mass Spectrometry Facility, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892