1. Department of Chemistry, Virginia Military Institute, Lexington, Virginia 24450, Laboratory of Bioorganic Chemistry, NIDDK, National Institutes of Health, HHS, Bethesda, Maryland 20892-0820, Department of Biology, University of Utah, 257 South, 1400 East, Salt Lake City, Utah 84112-0840, and Los Angeles County Museum of Natural History, 900 Exposition Boulevard, Los Angeles, California 90007