1. Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
2. Department of Chemistry, Southern Methodist University, Dallas, Texas, USA
3. Mass Spectrometry and Proteomics Facility, University of Notre Dame, Notre Dame, Indiana, USA
4. Stanford Synchrotron Radiation Lightsource, Stanford University, Menlo Park, California, USA
5. Department of Chemistry, Stanford University, Stanford, California, USA