1. Department of Biochemistry and Biophysics, Arrhenius Laboratories for Natural Sciences, Stockholm University, 10691 Stockholm, Sweden
2. School of Biological Sciences, Nanyang Technological University, 637551 Singapore
3. Gwangju Center, Korea Basic Science Institute, Gwangju 500-757, Republic of Korea
4. Division of Life Science, Korea Basic Science Institute, Daejeon 305-333, Korea
5. Graduate School of Analytical Science and Technology, Chungnam National University, Daejeon 305-764, Korea