1. 2Mass Spectrometry Research Center, Vanderbilt University, Nashville, Tennessee, USA
2. 1Department of Biochemistry, Vanderbilt University, Nashville, Tennessee, USA; email: jeff.spraggins@vanderbilt.edu
3. 3Department of Chemistry, Vanderbilt University, Nashville, Tennessee, USA
4. 4Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee, USA
5. 5Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA