1. Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94143-0446
2. CombiChem, Inc., 9050 Camino Sante Fe, San Diego, CA 92121
3. Laboratory of Structural Biology, National Institutes of Health, Bethesda, MD 20892-5626
4. Department of Chemistry, University of San Francisco, San Francisco, CA 94117-1080
5. Department of Chemistry, Universityof Warsaw, Pastera 1, 02-093 Warsaw, Poland