1. Pharmaceutical Research Center; School of Pharmacy; Guangzhou Medical University; 195 Dongfengxi Rd Guangzhou 510182 China
2. Division of Theoretical Chemistry and Biology; School of Biotechnology; KTH Royal Institute of Technology; 106 91 Stockholm Sweden
3. Department of Biochemistry and Molecular Biophysics; Washington University School of Medicine; St. Louis Missouri 63110 USA
4. Department of Biochemistry, Microbiology and Immunology; University of Ottawa; 451 Smyth Rd Ottawa ON Canada