Department of Biochemistry, The University of Hong Kong, Pokfulam, Hong Kong and Hunan Business College, Changsha, Hunan 410205, China. limx54@yahoo.com|Department of Biochemistry, The University of Hong Kong, Pokfulam, Hong Kong and Hunan Business College, Changsha, Hunan 410205, China. limx54@yahoo.com|Department of Biochemistry, The University of Hong Kong, Pokfulam, Hong Kong and Hunan Business College, Changsha, Hunan 410205, China. limx54@yahoo.com|Department of Biochemistry, The University of Hong Kong, Pokfulam, Hong Kong and Hunan Business College, Changsha, Hunan 410205, China. limx54@yahoo.com|Department of Biochemistry, The University of Hong Kong, Pokfulam, Hong Kong and Hunan Business College, Changsha, Hunan 410205, China. limx54@yahoo.com