Ye Hu1, Jürgen Bajorath2. 1. Department of Life Science Informatics, B-IT, LIMES Program Unit Chemical Biology and Medicinal Chemistry, Rheinische Friedrich-Wilhelms-Universität, D-53113 Bonn, Germany. 2. Department of Life Science Informatics, B-IT, LIMES Program Unit Chemical Biology and Medicinal Chemistry, Rheinische Friedrich-Wilhelms-Universität, D-53113 Bonn, Germany. Electronic address: bajorath@bit.uni-bonn.de.