1. Department of Chemistry, State University of New York at Stony Brook, Stony Brook, New York 11794-3400, Institute for Chemical Biology and Drug Discovery, State University of New York at Stony Brook, Stony Brook, New York 11794-3400, and Graduate Program in Biochemistry and Structural Biology, State University of New York at Stony Brook, Stony Brook, New York 11794-3400