1. Institute of Computing Science, Poznan University of Technology, 60-965 Poznan, Poland, 2Institute of Bioorganic Chemistry, Polish Academy of Sciences, 61-704 Poznan, Poland, 3Laboratory of Bioinformatics and Protein Engineering, International Institute of Molecular and Cell Biology, 02-109 Warsaw, Poland and 4Laboratory of Bioinformatics, Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University, 61-614 Poznan, Poland