1. Mass Spectrometry Research Center, Vanderbilt University, Nashville, Tennessee 37235, United States
2. Department of Biochemistry, Vanderbilt University, Nashville, Tennessee 37205, United States
3. Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, United States
4. Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232, United States
5. Department of Cell & Developmental Biology, Vanderbilt University, Nashville, Tennessee 37232, United States