1. Department of Chemistry, University of California, Berkeley, California 94720, USA
2. Novartis-Berkeley Center for Proteomics and Chemistry Technologies, University of California, Berkeley, California 94720, USA
3. Innovative Genomics Institute, University of California, Berkeley, California 94720, USA
4. Novartis Institute for BioMedical Research, Cambridge, Massachusetts 02139, USA
5. Department of Molecular and Cellular Biology, University of California, Berkeley, California 94720, USA