1. Department of Chemistry, P.O. Box 30012, Texas A&M University, College Station, Texas 77842-3012
2. Biology Department, Brookhaven National Laboratory, Upton, New York 11973
3. Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843
4. Lilly Biotechnology Center, 10300 Campus Point Drive, San Diego, California 92121