1. Department of Chemistry, Centro de Investigación y de Estudios Avanzados (Cinvestav), Mexico City 07360, Mexico
2. Laboratorio de Biofisicoquímica, Facultad de Química, Universidad Nacional Autónoma de México (UNAM), Mexico City 04510, Mexico
3. Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142, United States
4. Stanford Synchrotron Radiation Lightsource (SSRL), SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States