1. Contribution from the Department of Applied Science, University of California, Davis, California 95616, Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, Department of Chemistry, Stanford University, Stanford, California 94305, Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, and JASRI, SPring-8, 1-1-1 Kouto, Mikazuki-cho, Sayo-gun,...