1. Department of Biochemistry, Stanford University, Stanford, CA 94305, USA.
2. Stanford Synchrotron Radiation Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA.
3. Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA 94158, USA.
4. Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA.
5. Stanford ChEM-H, Stanford University, Stanford, CA 94305, USA.