1. Department of Organic Chemistry, Umeå University, S-90187 Umeå, Sweden, VTT, Chemical Technology, POB 1401 FIN-02044 Espoo, Finland, Turku Centre for Biotechnology, POB 123 FIN-20521 Turku, Finland, Department of Biochemistry and Pharmacy, Åbo Akademi University, POB 66, FIN-20521 Turku, Finland, and Department of Biophysics, Arrhenius Laboratories, Stockholm University, S-10691 Stockholm, Sweden