1. Department of Physics, Syracuse University, 201 Physics Building, Syracuse, New York 13244-1130, Department of Biochemistry, and Molecular and Cell Biology, Northwestern University, 2205 Tech Drive, Evanston, Illinois 60208-3500, Structural Biology, Biochemistry, and Biophysics Program, Syracuse University, 111 College Place, Syracuse, New York 13244-4100, and The Syracuse Biomaterials Institute, Syracuse University, 121 Link Hall, Syracuse, New York 13244