1. Institute of Theoretical Chemistry, Jilin University; Changchun 130023 People's Republic of China
2. Key Laboratory for Molecular Enzymology and Engineering of Ministry of Education, National Engineering Laboratory for AIDS Vaccine, College of Life Sciences; Jilin University; Changchun 130012 People's Republic of China
3. Bethune pharmaceutical factory, Jilin University; Changchun 130012 People's Republic of China
4. Department of Computer Science; C.S. Bond Life Sciences Center, University of Missouri Columbia; Missouri 65211