1. Department of Molecular Biology and Biochemistry University of Califronia, Irvine Irvine CA 92697-3900 USA
2. Department of Chemistry University of California, Irvine Irvine CA 92697-2025 USA
3. Institute for Chemical Research Kyoto University Gokasho, Uji, Kyoto 611-0011 Japan
4. Stanford Synchrotron Radiation Lightsource SLAC National Accelerator Laboratory Stanford University Menlo Park CA 94025 USA
5. Department of Chemistry Stanford University Stanford CA 94305 USA