1. Institute of Biochemistry, Department of Chemistry, University of Natural Resources and Life Sciences, Vienna, Muthgasse 18, A-1190Vienna, Austria
2. BIMEF Laboratory, Department of Chemistry, University of Antwerp, 2000Antwerp, Belgium
3. Department of Life Sciences, University of Modena and Reggio Emilia, 41100Modena, Italy
4. Department of Chemistry and Geology, University of Modena and Reggio Emilia, 41100Modena, Italy