1. Institute of Crystallography, Russian Academy of Sciences, Leninsky pr. 59, 119333 Moscow, Russia, Biomedical Engineering, Shanghai Jiao Tong University, 1954 Huashan Road, Shanghai 200030, China, Structural Biochemistry Laboratory, RIKEN Harima Institute, Spring-8, Hyogo 679-5148, Japan, and Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin-Lu, Shanghai 200032, China