1. Department of Chemistry and Biochemistry, University of Oklahoma, 620 Parrington Oval, Norman, Oklahoma 73019, USA, M. E. Müller Institute for Structural Biology, the Department of Structural Biology, Biozentrum, University of Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland, School of Chemistry, University of Birmingham, Edgbaston, Birmingham, B15 2TT, U.K., and the Department of Chemical Engineering, Chenshiu Institute of Technology, Kaohsiung, Taiwan, Republic of China