1. Department of Life Science and Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang 790-784, Republic of Korea, Mass Spectrometer Development Team, Korea Basic Science Institute, Daejeon 305-333, Republic of Korea, Department of Biotechnology, College of Engineering, Yonsei University, Seoul 120-749, Republic of Korea, and Institute of Biomedical Science and Technology, Department of Molecular Biotechnology, Konkuk University, Seoul 143-701, Republic of Korea