1. Chemistry Department, Umeå University, 901 87 Umeå, Sweden
2. Department of Computer and Systems Sciences, Stockholm University, Box 7003, 164 07 Kista, Sweden
3. MTM Research Centre, School of Science and Technology, Örebro University, 701 82 Örebro, Sweden
4. Department of Pharmaceutical Biosciences, Uppsala University, Box 591, 75 124 Uppsala, Sweden