1. Department
of 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 Biomedicine, University of Bergen, Jonas Lies vei 91, 5009 Bergen, Norway
3. Department
of Chemistry, University of Turku, FI-20014 Turku, Finland
4. Program
in Structural Biology and Biophysics, Institute of Biotechnology, University of Helsinki, P.O. Box 65, FI-00014 Helsinki, Finland