1. Department of Pharmacology, Yale University School of Medicine, New Haven, CT 06520, USA.
2. Department of Chemistry, Yale University, New Haven, CT 06520, USA.
3. Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06510, USA.
4. Keck MS and Proteomics Resource, Yale University School of Medicine, New Haven, CT 06510, USA.