1. Departments of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, China
2. MOE Key Laboratory of Protein Sciences, Beijing Advanced Innovation Center for Structural Biology, Beijing Frontier Research Center for Biological Structure, Department of Basic Medical Sciences, School of Medicine, Tsinghua University, Beijing 100084, China
3. Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing 100084, China