[1] UNIV CHICAGO,SEARLE CHEM LAB,DEPT CHEM,CHICAGO,IL 60637
[2] UNIV CHICAGO,SEARLE CHEM LAB,DEPT BIOCHEM,CHICAGO,IL 60637
[3] UNIV CHICAGO,DEPT MED,CHICAGO,IL 60637
[4] UNIV CHICAGO,DEPT MICROBIOL,CHICAGO,IL 60637
[5] MIT,DEPT BIOL,CAMBRIDGE,MA 02139