1. Department of Chemistry, Wyeth-Ayerst Research, CN-8000, Princeton, New Jersey 08543-8000, Department of Molecular Biology, Scripps Clinic and Research Foundation, La Jolla, California 92037, Department of Pathology and Laboratory of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, and A. M. Technologies Inc., 14785 Omicron Drive, San Antonio, Texas 78245