1. BioInfoBank Institute, Limanowskiego 24A/16, 60-744 Poznan, Poland, Interdisciplinary Centre for Mathematical and Computational Modeling, University of Warsaw, Warsaw, Poland, and Department of Chemistry, Istituto di Ricerche di Biologia Molecolare P. Angeletti, Merck Research Laboratories, Rome, Via Pontina km 30600, Pomezia 00040, Italy