1. Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California 93106, United States
2. Department of Pharmacology and Molecular Sciences, Johns Hopkins School of Medicine, Baltimore, Maryland 21205, United States
3. Aptitude Medical Systems, Inc., Santa Barbara, California 93105, United States
4. Interdepartmental Program in Biomolecular Science and Engineering University of California, Santa Barbara, Santa Barbara, California 93106, United States