1. Department of Chemistry, P.O. Box 30012, Texas A&M University, College Station, Texas 77842-3012
2. Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461
3. Department of Biotherapeutic Sciences, School of Pharmacy, University of California, 1700 4th Street, San Francisco, California 94158-2550
4. Department of Pharmaceutical Chemistry, School of Pharmacy, University of California, 1700 4th Street, San Francisco, California 94158-2330