Affiliation: | Department of Biochemistry,1 Department of Pharmacology University of Texas Southwestern Medical Center, Dallas, Texas 75390-9038,3 Department of Microbiology and Immunology, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814,2 Department of Bio-Organic Chemistry, Bijvoet Center, Utrecht University, 3508 TB Utrecht, The Netherlands4 |