1. Food and
Environmental Sciences, Division of Microbiology and Biotechnology, University of Helsinki, P.O. Box 56, Viikki Biocenter, Viikinkaari 9, FI-00014 Helsinki, Finland
2. Department of Chemistry and Centre for Pharmacy, University of Bergen, Allégaten 41, 5007 Bergen, Norway
3. Program in Structural
Biology and Biophysics, Institute of Biotechnology, University of Helsinki, P.O. Box 65, FI-00014 Helsinki, Finland