1. Environmental Energy Technologies Division, Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, California 94720
2. Stanford Synchrotron Radiation Laboratory, Sand Hill Road, Menlo Park, California 94025
3. Environmental Energy Technologies Division, Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, California 94720, and Department of Chemical Engineering, University of California, Berkeley, California 94720
4. Structural Biology Division, Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, California 94720, and Department of Applied Science, University of California, Davis, California 95616