1. Department of Chemistry and Biochemistry, University of California, Santa Cruz, 1156 High Street, Santa Cruz, California 95064, U.S.A., GluMetrix, Inc. 15375 Barranca Parkway, Suite I-108, Irvine, California 92618, U.S.A., and Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, U.S.A.